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2009-06-17
Full Text Available.A-kinase anchoring protein (AKAP) 79/150 is a scaffold protein found in dendritic spines that recruits the cAMP-dependent protein kinase (PKA) and protein phosphatase 2B-calcineurin (CaN) to membrane-associated guanylate kinase (MAGUK)-linked AMPA receptors (AMPAR) to control receptor phosphorylation and synaptic plasticity. However, AKAP79/150 may also coordinate regulation of AMPAR activity with spine structure directly through MAGUK binding and membrane-cytoskeletal interactions of its N-terminal targeting domain. In cultured hippocampal neurons, we observed that rat AKAP150 expression was low early in development but then increased coincident with spine formation and maturation. Overexpression of human AKAP79 in immature or mature neurons increased the number of dendritic filopodia and spines and enlarged spine area. However, RNAi knockdown of AKAP150 decreased dendritic spine area only in mature neurons. Importantly, AKAP79 overexpression in immature neurons increased AMPAR postsynaptic localization and activity. Neither the AKAP79 PKA nor CaN anchoring domain was required for increasing dendritic protrusion numbers, spine area or AMPAR synaptic localization; however, an internal region identified as the MAGUK binding domain was found to be essential as shown by expression of a MAGUK binding mutant that formed mainly filopodia and decreased AMPAR synaptic localization and activity. Expression of the AKAP79 N-terminal targeting domain alone also increased filopodia numbers but not spine area. Overall, these results demonstrate a novel structural role for AKAP79/150 where the N-terminal targeting domain induces dendritic filopodia and binding to MAGUKs promotes spine enlargement and AMPAR recruitment.
2009-06-17
A-kinase anchoring protein (AKAP) 79/150 is a scaffold protein found in dendritic spines that recruits the cAMP-dependent protein kinase (PKA) and protein phosphatase 2B-calcineurin (CaN) to...Full Text Available
http://handle.unsw.edu.au/1959.4/41512
Cyclic-AMP dependent protein kinase A (PKA) regulates traffic of multiple proteins at different stages along the constitutive secretory pathway. PKA effects are regulated by protein phosphatases, which reverse the actions of PKA by dephosphorylation of PKA-substrates. Localization of specific PKA effects is mediated by the binding of A-kinase anchoring proteins (AKAPs). Apolipoprotein E (apoE) is an important regulator of lipid metabolism and atherosclerosis, and represents a large proportion of total protein constitutively secreted from macrophages. The signalling and trafficking pathways regulating secretion of apoE are unknown. Catalase is a peroxisomal enzyme which contributes to defence against hydrogen peroxide (H2O2). The primary hypothesis of this thesis is PKA and related protein phosphatase pathways are involved in the regulation of apoE secretion. The secondary hypothesis is that these pathways also regulate cellular clearance of H2O2. In Chapter Three, I have investigated the role of PKA in apoE secretion from primary human macrophages. Structurally distinct inhibitors of PKA (H89, KT5720, inhibitory peptide PKI14-22) all decreased basal secretion of apoE by between 50-80% whereas apoE mRNA or cellular protein are unaffected. Disruption of PKA-AKAP anchoring also significantly inhibited apoE secretion from human macrophages. Secretion of apoE was not immediately stimulated by PKA activity, suggesting that although PKA activity may be permissive for apoE secretion, it is in itself insufficient to stimulate apoE secretion above basal levels. Data from confocal microscopy and live cell imaging revealed PKA inhibition paralysed apoE vesicular movement from and to the plasma membrane. In Chapter Four, I investigated the effects of protein phosphatase 2B (PP2B) inhibition on apoE secretion by cyclosporin A (CsA). This was found to dose- and time-dependently inhibit secretion of apoE from primary human macrophages and increased cellular accumulation of apoE without affecting apoE mRNA levels. The role of PP2B in regulating apoE secretion was confirmed by using additional peptide and chemical inhibitors of PP2B. This effect was independent of the known inhibition of ABCA1 by CsA. Live cell imaging and confocal microscopy all demonstrated that inhibition of PP2B did not affect the apparent cellular distribution of apoE. Biochemical and microscopy studies indicated distinct mechanisms for PKA and PP2B regulation of apoE secretion. Chapter Five identified PKA-anchoring AKAPs in human macrophages, and investigated AKAP220 expression and its role in PKA-dependent processes relevant to atherosclerosis. AKAP220 protein was absent in human monocytes but was detectable after their differentiation into macrophages, with stable expression during late stages of maturation. It was also present in Chinese Hamster Ovary cells (CHO) cells. AKAP220 silencing had no effects on lipoprotein cholesteryl ester accumulation, total cellular apoE levels, apoE secretion or cholesterol efflux from human macrophages. Confocal microscopy in CHO cells revealed peroxisomal localisation of AKAP220. Catalase activity was confirmed to be PKA-regulated process, and AKAP220 was found to be a negative regulator of catalase activity, such that cell lysate catalase activity increased during AKAP220 silencing. AKAP220 silencing also decreased basal secretion of H2O2, detected using a sensitive and specific Amplex?? Red assay kit from intact CHO monolayers. In conclusion, this thesis has provided evidence that apoE secretion occurs via PKA- and PP2B-dependent pathways in human macrophages, and has identified the A-kinase anchoring protein AKAP220 as a regulator of cellular H2O2 clearance. These results will provide a basis for future investigations into the roles of PKA-related pathways in apoE secretion and catalase activity. Publisher: Awarded By:University of New South Wales. Centre for Vascular Research Language: EN Rights: http://unsworks.unsw.edu.au/copyright
http://espace.library.uq.edu.au/view/UQ:79580
In the process of internalization of molecules from the extracellular milieu, a cell uses multiple endocytic pathways, consequently generating different endocytic vesicles. These primary endocytic vesicles are targeted to specific destinations inside the cell. Here, we show that GPI-anchored proteins are internalized by an Arf6-independent mechanism into GPI-anchored protein-enriched early endosomal compartments (GEECs). Internalized GPI-anchored proteins and the fluid phase are first visualized in GEECs that are acidic, primary endocytic structures, negative for early endosomal markers, Rab4, Rab5, and early endosome antigen (EEA)1. They subsequently acquire Rab5 and EEA1 before homotypic fusion with other GEECs, and heterotypic fusion with endosomes containing cargo from the clathrin-dependent endocytic pathway. Although, the formation of GEECs is unaffected by inhibition of Rab5 GTPase and phosphatidylinositol-3'-kinase (PI3K) activity, their fusion with sorting endosomes is dependent on both activities. Overexpression of Rab5 reverts PI3K inhibition of fusion, providing evidence that Rab5 effectors play important roles in heterotypic fusion between the dynamin-independent GEECs and clathrin- and dynamin-dependent sorting endosomes. Publisher: American Society of Cell Biology Relation: isMemberOf Institute for Molecular Bioscience - Publications; isMemberOf Excellence in Research Australia (ERA) - Collection
http://espace.library.uq.edu.au/view/UQ:75639
Proteins secreted by and anchored on the surfaces of parasites are in intimate contact with host tissues. The transcriptome of infective cercariae of the blood fluke, Schistosoma mansoni, was screened using signal sequence trap to isolate cDNAs encoding predicted proteins with an N-terminal signal peptide. Twenty cDNA fragments were identified, most of which contained predicted signal peptides or transmembrane regions, including a novel putative seven-transmembrane receptor and a membrane-associated mitogen-activated protein kinase. The developmental expression pattern within different life-cycle stages ranged from ubiquitous to a transcript that was highly upregulated in the cercaria. A bioinformatics-based comparison of 100 signal peptides from each of schistosomes, humans, a parasitic nematode and Escherichia coli showed that differences in the sequence composition of signal peptides, notably the residues flanking the predicted cleavage site, might account for the negative bias exhibited in the processing of schistosome signal peptides in mammalian cells. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. Relation: isMemberOf Excellence in Research Australia (ERA) - Collection; isMemberOf School of Medicine Publications Coverage: 2005-01-01T00:00:00Z
http://espace.library.uq.edu.au/view/UQ:74647
The glycine receptor chloride channel (GlyR) is a member of the nicotinic acetylcholine receptor family of ligand-gated ion channels. Functional receptors of this family comprise five subunits and are important targets for neuroactive drugs. The GlyR is best known for mediating inhibitory neurotransmission in the spinal cord and brain stem, although recent evidence suggests it may also have other physiological roles, including excitatory neurotransmission in embryonic neurons. To date, four alpha-subunits (alpha1 to alpha4) and one beta-subunit have been identified. The differential expression of subunits underlies a diversity in GlyR pharmacology. A developmental switch from alpha2 to alpha1beta is completed by around postnatal day 20 in the rat. The beta-subunit is responsible for anchoring GlyRs to the subsynaptic cytoskeleton via the cytoplasmic protein gephyrin. The last few years have seen a surge in interest in these receptors. Consequently, a wealth of information has recently emerged concerning Glyl? molecular structure and function. Most of the information has been obtained from homomeric alpha1 GlyRs, with the roles of the other subunits receiving relatively little attention. Heritable mutations to human GlyR genes give rise to a rare neurological disorder, hyperekplexia (or startle disease). Similar syndromes also occur in other species. A rapidly growing list of compounds has been shown to exert potent modulatory effects on this receptor. Since GlyRs are involved in motor reflex circuits of the spinal cord and provide inhibitory synapses onto pain sensory neurons, these agents may provide lead compounds for the development of muscle relaxant and peripheral analgesic drugs. Publisher: American Physiological Society Relation: isMemberOf Excellence in Research Australia (ERA) - Collection; isMemberOf School of Biomedical Sciences Publications
http://espace.library.uq.edu.au/view/UQ:73685
The spatial organization of plasma membrane components in discrete microdomains is thought to be a key factor in the generation of distinct signal outputs. A detailed characterization of plasma membrane microdomains, including descriptions of their size, dynamics and abundance, has proved to be a taxing problem for cell biologists and biophysicists. The use of novel techniques is providing exciting new insights into the challenging problem of plasma membrane microstructure and has allowed the visualization of domains with the characteristics expected of lipid rafts - microdomains of the plasma membrane enriched in cholesterol and sphingolipids. This review focuses on some of these recent advances and uses Ras signaling as a paradigm for understanding inner plasma membrane organization and the role of lipid rafts in cellular function. Publisher: Elsevier Ltd., Trends Journals Relation: isMemberOf Institute for Molecular Bioscience - Publications; isMemberOf Excellence in Research Australia (ERA) - Collection
http://espace.library.uq.edu.au/view/UQ:71327
Over the last two decades, the biochemistry and genetics of dimethylsulfoxide (DMSO) and trimethylamine-N-oxide (TMAO) respiration has been characterised, particularly in Escherichia coli, marine bacteria of the genus Shewanella and the purple phototrophic bacteria, Rhodobacter sphaeroides and R. capsulatus. All of the enzymes (or catalytic subunits) involved the final step in DMSO and TMAO respiration contain a pterin molybdenum cofactor and are members of the DMSO reductase family of molybdoenzymes. In E coli, the dimethylsulfoxide reductase (DmsABC) can be purified from membranes as a complex, which exhibits quinol-DMSO oxidoreductase activity. The enzyme is anchored to the membrane via the DmsC subunit and its catalytic subunit DmsA is now considered to face the periplasm. Electron transfer to DmsA involves the DmsB subunit, which is a polyferredoxin related to subunits found in other molybdoenzymes such as nitrate reductase and formate dehydrogenase. A characteristic of the DmsAB-type DMSO reductase is its ability to reduce a variety of S- and N-oxides. E. coli contains a trimethylamine-N-oxide reductase (TorA) that is highly specific for N-oxides. This enzyme is located in the periplasm and is connected to the quinone pool via a membrane-bound penta-haem cytochrome (TorC). DorCA in purple phototrophic bacteria of the genus Rhodobacter is very similar to TorCA with the critical difference that DorA catalyses reduction of both DMSO and TMAO. It is known as a DMSO reductase because the S-oxide is the best substrate. Crystal structures of DorA and TorA have revealed critical differences at the Mo active site that may explain the differences between substrate specificity between the two enzymes. DmsA, TorA and DorA possess a twin arginine N-terminal signal sequence consistent with their secretion via the TAT secretory system and not the See system. The enzymes are secreted with their bound prosthetic groups: this take place in the cytoplasm and the biogenesis involves a chaperone protein, which is cognate for each enzyme. Expression of the DMSO and TMAO respiratory operons is induced in response to a fall in oxygen tension. dmsABC expression is positively controlled by the oxygen-responsive transcription factor, Fnr and ModE, a transcription factor that binds molybdate. In contrast, torCAD expression is not under Fnr- or ModE-control but is dependent upon a sensor histidine kinase-response regulator pair, TorSR, which activate gene expression under conditions of low oxygen tension in the presence of N- or S-oxide. Regulation of dorCDA expression is similar to that seen for torCAD but it appears that the expression of the sensor histidine kinase-response regulator pair, DorSR is regulated by Fur and there is an additional tier of regulation involving the ModE-homologue MopB, molybdate and the transcription factor DorX. Analysis of microbial genomes has revealed the presence of dms and tor operons in a wide variety of bacteria and in some archaea and duplicate dms and tor operons have been identified in E. coli. Challenges ahead will include the determination of the significance of the presence of the dms operon in bacterial pathogens and the determination of the significance of DMSO respiration in the global turnover of marine organo-sulfur compounds. Publisher: Elsevier Relation: isMemberOf School of Chemistry and Molecular Biosciences; isMemberOf Excellence in Research Australia (ERA) - Collection
http://espace.library.uq.edu.au/view/UQ:61153
Ha-Ras and Ki-Ras have different distributions across plasma membrane microdomains. The Ras C-terminal anchors are primarily responsible for membrane microlocalization, but recent work has shown that the interaction of Ha-Ras with lipid rafts is modulated by GTP loading via a mechanism that requires the hypervariable region (HVR). We have now identified two regions in the HVR linker domain that regulate Ha-Ras raft association. Release of activated Ha-Ras from lipid rafts is blocked by deleting amino acids 173-179 or 166-172. Alanine replacement of amino acids 173-179 but not 166-172 restores wild type micro-localization, indicating that specific N-terminal sequences of the linker domain operate in concert with a more C-terminal spacer domain to regulate Ha-Ras raft association. Mutations in the linker domain that confine activated Ha-RasG12V to lipid rafts abrogate Raf-1, phosphoinositide 3-kinase, and Akt activation and inhibit PC 12 cell differentiation. N-Myristoylation also prevents the release of activated Ha-Ras from lipid rafts and inhibits Raf-1 activation. These results demonstrate that the correct modulation of Ha-Ras lateral segregation is critical for downstream signaling. Mutations in the linker domain also suppress the dominant negative phenotype of Ha-RasS17N, indicating that HVR sequences are essential for efficient interaction of Ha-Ras with exchange factors in intact cells. Publisher: American Society for Biochemistry & Molecular Biology Relation: isMemberOf Institute for Molecular Bioscience - Publications; isMemberOf Excellence in Research Australia (ERA) - Collection
http://espace.library.uq.edu.au/view/UQ:188577
Kindler syndrome (KS; OMIM173650) is an unusual, autosomal recessive skin disorder associated with trauma-induced blisters in early life followed by photosensitivity, poikiloderma, and an increased risk of malignancy. Defects in the actin/focal adhesion associated protein kindlin-1 (also known as kindlerin) encoded by the gene KIND1 have been shown to cause this disease. In human epidermis, kindlin-1 is expressed in epidermal keratinocytes, particularly within basal keratinocytes with an increase in staining at the dermal-epidermal junction. We have undertaken a detailed ultrastructural and immunohistochemical study in KS (n¼4) and control skin (n¼3) to examine morphology and the labeling of basement membrane, actin cytoskeletal, and focal contact-associated proteins. Transmission electron microscopy of KS skin showed disruption and reduplication of the lamina densa, together with sub-lamina separation. The number and structure of hemi-desmosomes and anchoring filaments appeared normal, although there was focal disruption in desmosome- and hemidesmosome-keratin filament attachment. This disruption in normal keratin filament assembly was most obvious at dermal splits and was associated with disorganized substratum bundles of actin filaments. Fluorescence microscopy showed increased epidermal expression of actin, alpha actinin, talin, vinculin, tenascin C, and RACK-1 in KS skin but no change in labeling with antibodies to filamin, tensin, focal adhesion kinase, paxillin, or tropomyosin. Immunostaining for protein kinase C was markedly reduced in basal keratinocytes in KS skin compared to controls. Immunogold electron microscopy using kindlin-1 antibody in control skin cytoplasm showed labeling over ends of microfilament-like structures. Taken together, our findings reveal a close spatial and functional relationship between kindlin-1, actin, some focal contact proteins and regulatory molecules that link the actin skeleton to the integrin extracellular matrix receptors. We hypothesize that the function of kindlin-1 might be to bind to the ends of actin microfilaments, linking focal adhesion proteins to integrin receptors at hemidesmosomes, thereby limiting the elongation of actin microfilaments. Conversely, a lack of kindlin-1 disrupts focal adhesion linkage and allows the unregulated proliferation of actin microfilaments, causing perturbations in the other cytoskeletal networks. Coverage: 2005-01-01T00:00:00Z
http://espace.library.uq.edu.au/view/UQ:188076
Kindler syndrome (KS; OMIM173650) is an unusual, autosomal recessive skin disorder associated with trauma-induced blisters in early life followed by photosensitivity, poikiloderma, and an increased risk of malignancy. Recently, defects in the actin/focal adhesion associated protein kindlin (also known as kinderlin) encoded by the gene KIND1 have been shown to cause this disease. In human epidermis, kindlin is expressed in epidermal keratinocytes, particularly within basal keratinocytes and at the dermal-epidermal junction (DEJ). We have undertaken a detailed ultrastructural and immunohistochemical study in KS (n¼2) and control skin (n¼3) to examine DEJ morphology and the labeling patterns of various basement membrane, actin cytoskeletal and focal contact-associated proteins. Transmission electron microscopy of KS skin showed disruption and reduplication of the lamina densa, together with sub-lamina densa cleft formation. The number and structure of hemidesmosomes and anchoring filaments appeared normal, although there was focal disruption in desmosome- and hemidesmosome-keratin filament attachment. This disruption in normal keratin filament assembly was most obvious at sites of dermal clefts and was associated with an abundance of substratum-associated, disorganized bundles of actin filaments. Immunofluorescence microscopy showed increased epidermal expression of actin, a actinin, talin, vinculin, tenascin C and RACK-1 in KS skin but no change in labeling with antibodies to filamin, tensin, focal adhesion kinase, paxillin or tropomyosin. Immunostaining for protein kinase C was markedly reduced in basal keratinocytes in KS skin compared to control. Taken together, our findings reveal a close spatial and functional relationship between kindlin, actin, some focal contact proteins and regulatory molecules that link the actin skeleton to the integrin extracellular matrix receptors. We hypothesize that the function of kindlin might be to bind to the terminal ends of actin microfilaments, linking focal adhesion proteins to the integrin receptors, thereby limiting the elongation of actin microfilaments. Conversely, a lack of kindlin might disrupt focal adhesion linkage and allow the unregulated proliferation of actin microfilaments causing perturbations in the associated actin and keratin cytoskeletal networks. Coverage: 2004-01-01T00:00:00Z
http://espace.library.uq.edu.au/view/UQ:112911
Over the last two decades, the biochemistry and genetics of dimethylsulfoxide (DMSO) and trimethylamine-N-oxide (TMAO) respiration has been characterised, particularly in Escherichia coli, marine bacteria of the genus Shewanella and the purple phototrophic bacteria, Rhodobacter sphaeroides and R. capsulatus. All of the enzymes (or catalytic subunits) involved the final step in DMSO and TMAO respiration contain a pterin molybdenum cofactor and are members of the DMSO reductase family of molybdoenzymes. In E coli, the dimethylsulfoxide reductase (DmsABC) can be purified from membranes as a complex, which exhibits quinol-DMSO oxidoreductase activity. The enzyme is anchored to the membrane via the DmsC subunit and its catalytic subunit DmsA is now considered to face the periplasm. Electron transfer to DmsA involves the DmsB subunit, which is a polyferredoxin related to subunits found in other molybdoenzymes such as nitrate reductase and formate dehydrogenase. A characteristic of the DmsAB-type DMSO reductase is its ability to reduce a variety of S- and N-oxides. E. coli contains a trimethylamine-N-oxide reductase (TorA) that is highly specific for N-oxides. This enzyme is located in the periplasm and is connected to the quinone pool via a membrane-bound penta-haem cytochrome (TorC). DorCA in purple phototrophic bacteria of the genus Rhodobacter is very similar to TorCA with the critical difference that DorA catalyses reduction of both DMSO and TMAO. It is known as a DMSO reductase because the S-oxide is the best substrate. Crystal structures of DorA and TorA have revealed critical differences at the Mo active site that may explain the differences between substrate specificity between the two enzymes. DmsA, TorA and DorA possess a "twin arginine" N-terminal signal sequence consistent with their secretion via the TAT secretory system and not the See system. The enzymes are secreted with their bound prosthetic groups: this take place in the cytoplasm and the biogenesis involves a chaperone protein, which is cognate for each enzyme. Expression of the DMSO and TMAO respiratory operons is induced in response to a fall in oxygen tension. dmsABC expression is positively controlled by the oxygen-responsive transcription factor, Fnr and ModE, a transcription factor that binds molybdate. In contrast, torCAD expression is not under Fnr- or ModE-control but is dependent upon a sensor histidine kinase-response regulator pair, TorSR, which activate gene expression under conditions of low oxygen tension in the presence of N- or S-oxide. Regulation of dorCDA expression is similar to that seen for torCAD but it appears that the expression of the sensor histidine kinase-response regulator pair, DorSR is regulated by Fur and there is an additional tier of regulation involving the ModE-homologue MopB, molybdate and the transcription factor DorX. Analysis of microbial genomes has revealed the presence of dms and tor operons in a wide variety of bacteria and in some archaea and duplicate dms and tor operons have been identified in E. coli. Challenges ahead will include the determination of the significance of the presence of the dms operon in bacterial pathogens and the determination of the significance of DMSO respiration in the global turnover of marine organo-sulfur compounds. Publisher: Elsevier Academic Press Inc Relation: isMemberOf School of Chemistry and Molecular Biosciences; isMemberOf Excellence in Research Australia (ERA) - Collection
axion: Axion - Java Database - News
The Axion news feed is on hiatus, yet Axion is still being actively developed. ... Better late than never, it's the Axion database project's October 2003 ...
A small, fast, SQL and JDBC compliant relational database engine written in and for the Java programming language. [Open source, BSD License]
arXiv:hep-ph/9506229 v1 02 Jun 95
File Format: PDF/Adobe Acrobat - View as HTMLThe axion is the quantum of oscillation of the ? parameter of QCD. It is a particle ... ticle physics is the PQ mechanism with an ?invisible? axion. ...
2005-11-07
Upon cross-linking by antigen, the high affinity receptor for immunoglobulin E (IgE), FcɛRI, is phosphorylated by the Src family tyrosine kinase Lyn to initiate mast cell signaling, leading...Full Text Available
2005-11-07
Full Text Available.Upon cross-linking by antigen, the high affinity receptor for immunoglobulin E (IgE), FcɛRI, is phosphorylated by the Src family tyrosine kinase Lyn to initiate mast cell signaling, leading to degranulation. Using fluorescence correlation spectroscopy (FCS), we observe stimulation-dependent associations between fluorescently labeled IgE-FcɛRI and Lyn-EGFP on individual cells. We also simultaneously measure temporal variations in the lateral diffusion of these proteins. Antigen-stimulated interactions between these proteins detected subsequent to the initiation of receptor phosphorylation exhibit time-dependent changes, suggesting multiple associations between FcɛRI and Lyn-EGFP. During this period, we also observe a persistent decrease in Lyn-EGFP lateral diffusion that is dependent on Src family kinase activity. These stimulated interactions are not observed between FcɛRI and a chimeric EGFP that contains only the membrane-targeting sequence from Lyn. Our results reveal real-time interactions between Lyn and cross-linked FcɛRI implicated in downstream signaling events. They demonstrate the capacity of FCS cross-correlation analysis to investigate the mechanism of signaling-dependent protein–protein interactions in intact, living cells.
T Antigens of Simian Virus 40: Molecular Chaperones for Viral Replication and Tumorigenesis
2002-06-01
Simian virus 40 (SV40) is a small DNA tumor virus that has been extensively characterized due to its relatively simple genetic organization and the ease with which its genome is manipulated. The large...Full Text Available
T Antigens of Simian Virus 40: Molecular Chaperones for Viral Replication and Tumorigenesis
2002-06-01
Full Text Available.Simian virus 40 (SV40) is a small DNA tumor virus that has been extensively characterized due to its relatively simple genetic organization and the ease with which its genome is manipulated. The large and small tumor antigens (T antigens) are the major regulatory proteins encoded by SV40. Large T antigen is responsible for both viral and cellular transcriptional regulation, virion assembly, viral DNA replication, and alteration of the cell cycle. Deciphering how a single protein can perform such numerous and diverse functions has remained elusive. Recently it was established that the SV40 T antigens, including large T antigen, are molecular chaperones, each with a functioning DnaJ domain. The molecular chaperones were originally identified as bacterial genes essential for bacteriophage growth and have since been shown to be conserved in eukaryotes, participating in an array of both viral and cellular processes. This review discusses the mechanisms of DnaJ/Hsc70 interactions and how they are used by T antigen to control viral replication and tumorigenesis. The use of the DnaJ/Hsc70 system by SV40 and other viruses suggests an important role for these molecular chaperones in the regulation of the mammalian cell cycle and sheds light on the enigmatic SV40 T antigen—a most amazing molecule.
1998-02-09
The ezrin/radixin/moesin (ERM) proteins are involved in actin filament/plasma membrane interaction that is regulated by Rho. We examined whether ERM proteins are directly phosphorylated by Rho- associated...Full Text Available
1998-02-09
Full Text Available.The ezrin/radixin/moesin (ERM) proteins are involved in actin filament/plasma membrane interaction that is regulated by Rho. We examined whether ERM proteins are directly phosphorylated by Rho- associated kinase (Rho-kinase), a direct target of Rho. Recombinant full-length and COOH-terminal half radixin were incubated with constitutively active catalytic domain of Rho-kinase, and ∼30 and ∼100% of these molecules, respectively, were phosphorylated mainly at the COOH-terminal threonine (T564). Next, to detect Rho-kinase–dependent phosphorylation of ERM proteins in vivo, we raised a mAb that recognized the T564-phosphorylated radixin as well as ezrin and moesin phosphorylated at the corresponding threonine residue (T567 and T558, respectively). Immunoblotting of serum-starved Swiss 3T3 cells with this mAb revealed that after LPA stimulation ERM proteins were rapidly phosphorylated at T567 (ezrin), T564 (radixin), and T558 (moesin) in a Rho-dependent manner and then dephosphorylated within 2 min. Furthermore, the T564 phosphorylation of recombinant COOH-terminal half radixin did not affect its ability to bind to actin filaments in vitro but significantly suppressed its direct interaction with the NH2-terminal half of radixin. These observations indicate that the Rho-kinase–dependent phosphorylation interferes with the intramolecular and/ or intermolecular head-to-tail association of ERM proteins, which is an important mechanism of regulation of their activity as actin filament/plasma membrane cross-linkers.
Protein kinesis: The dynamics of protein trafficking and stability
The purpose of this conference is to provide a multidisciplinary forum for exchange of state-of-the-art information on protein kinesis. This volume contains abstracts of papers in the following areas: protein folding and modification in the endoplasmic reticulum; protein trafficking; protein translocation and folding; protein degradation; polarity; nuclear trafficking; membrane dynamics; and protein import into organelles.
Protein kinesis: The dynamics of protein trafficking and stability
1995-12-31
The purpose of this conference is to provide a multidisciplinary forum for exchange of state-of-the-art information on protein kinesis. This volume contains abstracts of papers in the following areas: protein folding and modification in the endoplasmic reticulum; protein trafficking; protein translocation and folding; protein degradation; polarity; nuclear trafficking; membrane dynamics; and protein import into organelles.
Physical modulation of intracellular signaling processes by locational regulation.
1997-05-01
Recent observations in the field of signal transduction suggest that where a protein is located within a cell can be as important as its activity measured in solution for activation of its downstream...Full Text Available
Physical modulation of intracellular signaling processes by locational regulation.
1997-05-01
Full Text Available.Recent observations in the field of signal transduction suggest that where a protein is located within a cell can be as important as its activity measured in solution for activation of its downstream pathway. The physical organization of the cell can provide an additional layer of control upon the chemical reaction networks that govern ultimately perceived signals. Using the cytosol and plasma membrane as relevant compartmental distinctions, we analyze the effect of relocation on the rate of association with a membrane-associated target. We quantify this effect as an enhancement factor E in terms of measurable parameters such as the number of available targets, molecular diffusivities, and intrinsic reaction rate constants. We then employ two simple yet relevant example models to illustrate how relocation can affect the dynamics of signal transduction pathways. The temporal profiles and phase behavior of these models are investigated. We also relate experimentally observable aspects of signal transduction such as peak activation and the relative time scales of stimulus and response to quantitative aspects of the relocation mechanisms in our models. In our example schemes, nearly complete relocation of the cytosolic species in the signaling pair is required to generate meaningful activation of the model pathways when the association rate enhancement factor E is as low as 10; when E is 100 or greater, only a small fraction of the protein must be relocated.ImagesFIGURE 1FIGURE 3
1999-05-01
Receptor for activated C kinase 1 (RACK1) is an intracellular receptor for protein kinase C (PKC) that regulates the cellular enzyme localization....Full Text Available
1999-05-01
Full Text Available. Receptor for activated C kinase 1 (RACK1) is an intracellular receptor for protein kinase C (PKC) that regulates the cellular enzyme localization. Because opiate drugs modulate the levels of brain PKC (Ventayol et al., 1997), the aim of this study was to assess in parallel the effects of morphine on RACK1 and PKC-α and β isozymes densities in rat brain frontal cortex by immunoblot assays.Acute morphine (30 mg kg−1, i.p., 2 h) induced significant increases in the densities of RACK1 (33%), PKC-α (35%) and PKC-β (23%). In contrast, chronic morphine (10–100 mg kg−1, i.p., 5 days) induced a decrease in RACK1 levels (22%), paralleled by decreases in the levels of PKC-α (16%) and PKC-β (16%).Spontaneous (48 h) and naloxone (2 mg kg−1, i.p., 2 h)-precipitated morphine withdrawal after chronic morphine induced marked up-regulations in the levels of RACK1 (38–41%), PKC-α (51–52%) and PKC-β (48–62%).In the same brains and for all combined treatments, there were significant positive correlations between the density of RACK1 and those of PKC-α (r=0.85, n=35) and PKC-β (r=0.75, n=32).These data indicate that RACK1 is involved in the short- and long-term effects of morphine and in opiate withdrawal, and that RACK1 modulation by morphine or its withdrawal is parallel to those of PKC-α and β isozymes. Since RACK1 facilitates the PKC substrate accessibility, driving its cellular localization, the coordinate regulation of the PKC/RACK system by morphine could be a relevant molecular mechanism in opiate addiction.
Nesprin-1alpha contributes to the targeting of mAKAP to the cardiac myocyte nuclear envelope
2005-01-01
Muscle A-kinase anchoring protein (mAKAP) is a scaffold protein found principally at the nuclear envelope of striated myocytes. mAKAP maintains a complex consisting of multiple signal transduction molecules including the cAMP-dependent protein kinase A, the ryanodine receptor calcium release channel, phosphodiesterase type 4D3, and protein phosphatase 2A. By an unknown mechanism, a domain containing spectrin repeats is responsible for targeting mAKAP to the nuclear envelope. We now demonstrate that the integral membrane protein nesprin-1alpha serves as a receptor for mAKAP on the nuclear envelope in cardiac myocytes. Nesprin-1alpha is inserted into the nuclear envelope by a conserved, C-terminal, klarsicht-related transmembrane domain and forms homodimers by the binding of an amino-terminal spectrin repeat domain. Through the ... >>
Montreal Axion - Wikipedia, the free encyclopedia
The Montreal Axion are a National Women's Hockey League team located in Montreal, Quebec, Canada. v ? d ? e · Sports teams based in the province of Quebec, ...
2005-02-01
Members of the heat-shock protein (HSP)40 regulate the protein folding activity of HSP70 proteins and help the functional specialization of this molecular chaperone system in various types of cellular...Full Text Available
2005-02-01
Full Text Available.Members of the heat-shock protein (HSP)40 regulate the protein folding activity of HSP70 proteins and help the functional specialization of this molecular chaperone system in various types of cellular events. We have recently identified Hsp40 as a component of flagellar axoneme in the ascidian Ciona intestinalis, suggesting a correlation between Hsp40 related chaperone system and flagellar function. In this study, we have found that Ciona 37-kDa Hsp40 is extracted from KCl-treated axonemes with 0.5 M KI solution and comigrates with radial spoke protein (RSP)3 along with several proteins as a complex through gel filtration and ion exchange columns. Peptide mass fingerprinting with matrix-assisted laser desorption ionization/time of flight/mass spectrometry revealed that other proteins in the complex include a homolog of sea urchin spokehead protein (homolog of RSP4/6), a membrane occupation and recognition nexus repeat protein with sequence similarity with meichroacidin, and a functionally unknown 33-kDa protein. A spoke head protein, LRR37, is not included in the complex, suggesting that the complex constructs the stalk of radial spoke. Immunoelectron microscopy indicates that Hsp40 is localized in the distal portion of spoke stalk, possibly at the junction between spoke head and the stalk.
2004-01-01
We evaluated the evolutionary conservation of glycine myristoylation within eukaryotic sequences. Our large-scale cross-genome analyses, available as MYRbase, show that the functional spectrum of myristoylated...Full Text Available
2004-01-01
Full Text Available.We evaluated the evolutionary conservation of glycine myristoylation within eukaryotic sequences. Our large-scale cross-genome analyses, available as MYRbase, show that the functional spectrum of myristoylated proteins is currently largely underestimated. We give experimental evidence for in vitro myristoylation of selected predictions. Furthermore, we classify five membrane-attachment factors that occur most frequently in combination with, or even replacing, myristoyl anchors, as some protein family examples show.
Linkage Map of Escherichia coli K-12, Edition 10: The Traditional Map
1998-09-01
This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715–1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular...Full Text Available
Linkage Map of Escherichia coli K-12, Edition 10: The Traditional Map
1998-09-01
Full Text Available.This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715–1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.
2000-02-21
The catalytic (C) subunit of protein kinase A functions both in the cytoplasm and the nucleus. A major charge variant representing about one third of the enzyme in striated muscle results from deamidation...Full Text Available
2000-02-21
Full Text Available.The catalytic (C) subunit of protein kinase A functions both in the cytoplasm and the nucleus. A major charge variant representing about one third of the enzyme in striated muscle results from deamidation in vivo of the Asn2 residue at the conserved NH2-terminal sequence myrGly-Asn-Ala (Jedrzejewski, P.T., A. Girod, A. Tholey, N. König, S. Thullner, V. Kinzel, and D. Bossemeyer. 1998. Protein Sci. 7:457–469). Because of the increase of electronegativity by generation of Asp2, it is reminiscent of a myristoyl-electrostatic switch. To compare the intracellular distribution of the enzymes, both forms of porcine or bovine heart enzyme were microinjected into the cytoplasm of mouse NIH 3T3 cells after conjugation with fluorescein, rhodamine, or in unlabeled form. The nuclear/cytoplasmic fluorescence ratio (N/C) was analyzed in the presence of cAMP (in the case of unlabeled enzyme by antibodies). Under all circumstances, the N/C ratio obtained with the encoded Asn2 form was significantly higher than that with the deamidated, Asp2 form; i.e., the Asn2 form reached a larger nuclear concentration than the Asp2 form. Comparable data were obtained with a human cell line. The differential intracellular distribution of both enzyme forms is also reflected by functional data. It correlates with the degree of phosphorylation of the key serine in CREB family transcription factors in the nucleus. Microinjection of myristoylated recombinant bovine Cα and the Asn2 deletion mutant of it yielded N/C ratios in the same range as encoded native enzymes. Thus, Asn2 seems to serve as a potential site for modulating electronegativity. The data indicate that the NH2-terminal domain of the PKA C-subunit contributes to the intracellular distribution of free enzyme, which can be altered by site-specific in vivo deamidation. The model character for other signaling proteins starting with myrGly-Asn is discussed.
Genetics of Skin Cancer (PDQ®) (Health Professional)
Expert-reviewed information summary about the genetics of skin cancer ? basal cell carcinoma, squamous cell carcinoma, and melanoma ? including information about specific gene mutations and related cancer syndromes. The summary also contains information about interventions that may influence the risk of developing skin cancer in individuals who may be genetically susceptible to these syndromes.
Functions of the gene products of Escherichia coli.
1993-12-01
Full Text Available.A list of currently identified gene products of Escherichia coli is given, together with a bibliography that provides pointers to the literature on each gene product. A scheme to categorize cellular functions is used to classify the gene products of E. coli so far identified. A count shows that the numbers of genes concerned with small-molecule metabolism are on the same order as the numbers concerned with macromolecule biosynthesis and degradation. One large category is the category of tRNAs and their synthetases. Another is the category of transport elements. The categories of cell structure and cellular processes other than metabolism are smaller. Other subjects discussed are the occurrence in the E. coli genome of redundant pairs and groups of genes of identical or closely similar function, as well as variation in the degree of density of genetic information in different parts of the genome.
Functions of the gene products of Escherichia coli.
1993-12-01
A list of currently identified gene products of Escherichia coli is given, together with a bibliography that provides pointers to the literature on each gene product. A scheme to categorize cellular...Full Text Available
Functional Roles for Fatty Acylated Amino-terminal Domains in Subcellular Localization
1999-11-01
Several membrane-associating signals, including covalently linked fatty acids, are found in various combinations at the N termini of signaling proteins. The function of these combinations was investigated...Full Text Available
Functional Roles for Fatty Acylated Amino-terminal Domains in Subcellular Localization
1999-11-01
Full Text Available.Several membrane-associating signals, including covalently linked fatty acids, are found in various combinations at the N termini of signaling proteins. The function of these combinations was investigated by appending fatty acylated N-terminal sequences to green fluorescent protein (GFP). Myristoylated plus mono/dipalmitoylated GFP chimeras and a GFP chimera containing a myristoylated plus a polybasic domain were localized similarly to the plasma membrane and endosomal vesicles, but not to the nucleus. Myristoylated, nonpalmitoylated mutant chimeric GFPs were localized to intracellular membranes, including endosomes and the endoplasmic reticulum, and were absent from the plasma membrane, the Golgi, and the nucleus. Dually palmitoylated GFP was localized to the plasma membrane and the Golgi region, but it was not detected in endosomes. Nonacylated GFP chimeras, as well as GFP, showed cytosolic and nuclear distribution. Our results demonstrate that myristoylation is sufficient to exclude GFP from the nucleus and associate with intracellular membranes, but plasma membrane localization requires a second signal, namely palmitoylation or a polybasic domain. The similarity in localization conferred by the various myristoylated and palmitoylated/polybasic sequences suggests that biophysical properties of acylated sequences and biological membranes are key determinants in proper membrane selection. However, dual palmitoylation in the absence of myristoylation conferred significant differences in localization, suggesting that multiple palmitoylation sites and/or enzymes may exist.
Environmental Management Science Program Workshop. Proceedings
The Department of Energy Office of Environmental Management (EM), in partnership with the Office of Energy Research (ER), designed, developed, and implemented the Environmental Management Science Program as a basic research effort to fund the scientific and engineering understanding required to solve the most challenging technical problems facing the government's largest, most complex environmental cleanup program. The intent of the Environmental Management Science Program is to: (1) Provide scientific knowledge that will revolutionize technologies and cleanup approaches to significantly reduce future costs, schedules, and risks. (2) Bridge the gap between broad fundamental research that has wide-ranging applications such as that performed in the Department's Office of Energy Research and needs-driven applied technology development that is conducted in Environmental Management's Office of Science and Technology. (3) Focus the nation's science infrastructure on critical Department of Energy environmental problems. In an effort to share information regarding basic research efforts being funded by the Environmental Management Science Program and the Environmental Management/Energy Research Pilot Collaborative Research Program (Wolf-Broido Program), this CD includes summaries for each project. These project summaries, available in portable document format (PDF), were prepared in the spring of 1998 by the principal investigators and provide information about their most recent project activities and accomplishments.
Environmental Management Science Program Workshop. Proceedings
1998-07-01
The Department of Energy Office of Environmental Management (EM), in partnership with the Office of Energy Research (ER), designed, developed, and implemented the Environmental Management Science Program as a basic research effort to fund the scientific and engineering understanding required to solve the most challenging technical problems facing the government's largest, most complex environmental cleanup program. The intent of the Environmental Management Science Program is to: (1) Provide scientific knowledge that will revolutionize technologies and cleanup approaches to significantly reduce future costs, schedules, and risks. (2) Bridge the gap between broad fundamental research that has wide-ranging applications such as that performed in the Department's Office of Energy Research and needs-driven applied technology development that is conducted in Environmental Management's Office of Science and Technology. (3) Focus the nation's science infrastructure on critical Department of Energy environmental problems. In an effort to share information regarding basic research efforts being funded by the Environmental Management Science Program and the Environmental Management/Energy Research Pilot Collaborative Research Program (Wolf-Broido Program), this CD includes summaries for each project. These project summaries, available in portable document format (PDF), were prepared in the spring of 1998 by the principal investigators and provide information about their most recent project activities and accomplishments.
Environmental Management Science Program Workshop
This program summary book is a compendium of project summaries submitted by principal investigators in the Environmental Management Science Program and Environmental Management/Energy Research Pilot Collaborative Research Program (Wolf-Broido Program). These summaries provide information about the most recent project activities and accomplishments. All projects will be represented at the workshop poster sessions, so you will have an opportunity to meet with the researchers. The projects will be presented in the same order at the poster session as they are presented in this summary book. Detailed questions about an individual project may be directed to the investigators involved.
Environmental Management Science Program Workshop
1998-07-01
This program summary book is a compendium of project summaries submitted by principal investigators in the Environmental Management Science Program and Environmental Management/Energy Research Pilot Collaborative Research Program (Wolf-Broido Program). These summaries provide information about the most recent project activities and accomplishments. All projects will be represented at the workshop poster sessions, so you will have an opportunity to meet with the researchers. The projects will be presented in the same order at the poster session as they are presented in this summary book. Detailed questions about an individual project may be directed to the investigators involved.
Division of energy biosciences: Annual report and summaries of FY 1995 activities
The mission of the Division of Energy Biosciences is to support research that advances the fundamental knowledge necessary for the future development of biotechnologies related to the Department of Energy`s mission. The departmental civilian objectives include effective and efficient energy production, energy conservation, environmental restoration, and waste management. The Energy Biosciences program emphasizes research in the microbiological and plant sciences, as these understudied areas offer numerous scientific opportunities to dramatically influence environmentally sensible energy production and conservation. The research supported is focused on the basic mechanisms affecting plant productivity, conversion of biomass and other organic materials into fuels and chemicals by microbial systems, and the ability of biological systems to replace energy-intensive or pollutant-producing processes. The Division also addresses the increasing number of new opportunities arising at the interface of biology with other basic energy-related sciences such as biosynthesis of novel materials and the influence of soil organisms on geological processes.
Division of Energy Biosciences annual report and summaries of FY 1996 activities
The mission of the Division of Energy Biosciences is to support research that advances the fundamental knowledge necessary for the future development of biotechnologies related to the Department of Energy`s mission. The departmental civilian objectives include effective and efficient energy production, energy conservation, environmental restoration, and waste management. The Energy Biosciences program emphasizes research in the microbiological and plant sciences, as these understudied areas offer numerous scientific opportunities to dramatically influence environmentally sensible energy production and conservation. The research supported is focused on the basic mechanism affecting plant productivity, conversion of biomass and other organic materials into fuels and chemicals by microbial systems, and the ability of biological systems to replace energy-intensive or pollutant-producing processes. The Division also addresses the increasing number of new opportunities arising at the interface of biology with other basic energy-related sciences such as biosynthesis of novel materials and the influence of soil organisms on geological processes. This report gives summaries on 225 projects on photosynthesis, membrane or ion transport, plant metabolism and biosynthesis, carbohydrate metabolism lipid metabolism, plant growth and development, plant genetic regulation and genetic mechanisms, plant cell wall development, lignin-polysaccharide breakdown, nitrogen fixation and plant-microbial symbiosis, mechanism for plant adaptation, fermentative microbial metabolism, one and two carbon microbial metabolism, extremophilic microbes, microbial respiration, nutrition and metal metabolism, and materials biosynthesis.
Designing new cellular signaling pathways
2009-03-27
SummaryAll cells respond to signals from the environment. Extracellular stimuli activate intracellular signal transduction pathways that make decisions about cell identity, behavior,...Full Text Available
Designing new cellular signaling pathways
2009-03-27
Full Text Available.SummaryAll cells respond to signals from the environment. Extracellular stimuli activate intracellular signal transduction pathways that make decisions about cell identity, behavior, and survival. A nascent field aims to design and construct new signaling pathways beyond those found in nature. Current strategies exploit the structural modularity of many signaling proteins, which makes them inherently amenable to domain swapping tactics that exchange their input and output connections. The results reveal a remarkable degree of functional plasticity in signaling proteins and pathways, as well as regulatory logic that can be transported to new proteins. Modified adaptor and scaffold proteins can reroute signal traffic and adjust the response behavior of the pathway circuit. These synthetic biology approaches promise to deepen our understanding of existing signaling pathways and spur development of new cellular tools for research, industry, and medicine.
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Axion Project Incubation Status - Apache Incubator
For general project status, see the Axion project website. ... The axion project never moved to the ASF from tigris.org. 2003-12-19: The Apache Incubator ...
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Axion - Wikipedia, the free encyclopedia
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7th international symposium on photosynthetic prokaryotes. Abstracts
This book contains the abstracts of all the presentations made either in oral or poster form, at the VII International Symposium on Photosynthetic Prokaryotes.
7th international symposium on photosynthetic prokaryotes. Abstracts
1991-12-31
This book contains the abstracts of all the presentations made either in oral or poster form, at the VII International Symposium on Photosynthetic Prokaryotes.
7th international symposium on photosynthetic prokaryotes
This book contains the abstracts of all the presentations made either in oral or poster form, at the VII International Symposium on Photosynthetic Prokaryotes.
7th international symposium on photosynthetic prokaryotes
1991-01-01
This book contains the abstracts of all the presentations made either in oral or poster form, at the VII International Symposium on Photosynthetic Prokaryotes.
22nd international conference on magnetic resonance in biological systems - ICMRBS 2006. Proceedings
2006-07-01
The volume contains abstracts of lectures and posters of the ICMRBS. Lecture headers were: folding aggregation, oligonucleotides, drug industry, labelling techniques, protein structure, membrane proteins, sparse data, protein-protein interaction, dynamic nuclear polarization, proteins, biosensors 'in cell', molecular probes, dynamics, optimized methods, heterogenous structures, geonomics, solid state, paramagnetic proteins, enzyme mechanisms and dynamics, metabonomics. (uke)
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