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Full-Text Articles in Medicine and Health Sciences
The Fly Camta Transcription Factor Potentiates Deactivation Of Rhodopsin, A G Protein-Coupled Light Receptor, Junhai Han, Ping Gong, Keith Reddig, Mirna Mitra, Peiyi Guo, Hong-Sheng Li
The Fly Camta Transcription Factor Potentiates Deactivation Of Rhodopsin, A G Protein-Coupled Light Receptor, Junhai Han, Ping Gong, Keith Reddig, Mirna Mitra, Peiyi Guo, Hong-Sheng Li
Peiyi Guo
Control of membrane-receptor activity is required not only for the accuracy of sensory responses, but also to protect cells from excitotoxicity. Here we report the isolation of two noncomplementary fly mutants with slow termination of photoresponses. Genetic and electrophysiological analyses of the mutants revealed a defect in the deactivation of rhodopsin, a visual G protein-coupled receptor (GPCR). The mutant gene was identified as the calmodulin-binding transcription activator (dCAMTA). The known rhodopsin regulator Arr2 does not mediate this visual function of dCAMTA. A genome-wide screen identified five dCAMTA target genes. Of these, overexpression of the F box gene dFbxl4 rescued the …
Molecular Basis Of Rna Recognition By The Embryonic Polarity Determinant Mex-5, John Pagano, Brian Farley, Lisa Mccoig, Sean Ryder
Molecular Basis Of Rna Recognition By The Embryonic Polarity Determinant Mex-5, John Pagano, Brian Farley, Lisa Mccoig, Sean Ryder
Sean P. Ryder
Embryonic development requires maternal proteins and RNA. In Caenorhabditis elegans, a gradient of CCCH tandem zinc finger (TZF) proteins coordinates axis polarization and germline differentiation. These proteins govern expression from maternal mRNAs by an unknown mechanism. Here we show that the TZF protein MEX-5, a primary anterior determinant, is an RNA-binding protein that recognizes linear RNA sequences with high affinity but low specificity. The minimal binding site is a tract of six or more uridines within a 9-13-nucleotide window. This sequence is remarkably abundant in the 3'-untranslated region of C. elegans transcripts, demonstrating that MEX-5 alone cannot specify mRNA target …
The N-Terminal Peptide Of The Syntaxin Tlg2p Modulates Binding Of Its Closed Conformation To Vps45p, Melonnie Furgason, Chris Macdonald, Scott Shanks, Sean Ryder, Nia Bryant, Mary Munson
The N-Terminal Peptide Of The Syntaxin Tlg2p Modulates Binding Of Its Closed Conformation To Vps45p, Melonnie Furgason, Chris Macdonald, Scott Shanks, Sean Ryder, Nia Bryant, Mary Munson
Sean P. Ryder
The Sec1/Munc18 (SM) protein family regulates intracellular trafficking through interactions with individual SNARE proteins and assembled SNARE complexes. Revealing a common mechanism of this regulation has been challenging, largely because of the multiple modes of interaction observed between SM proteins and their cognate syntaxin-type SNAREs. These modes include binding of the SM to a closed conformation of syntaxin, binding to the N-terminal peptide of syntaxin, binding to assembled SNARE complexes, and/or binding to nonsyntaxin SNAREs. The SM protein Vps45p, which regulates endosomal trafficking in yeast, binds the conserved N-terminal peptide of the syntaxin Tlg2p. We used size exclusion chromatography and …
Hnrnp A1 And Secondary Structure Coordinate Alternative Splicing Of Mag, Nancy Zearfoss, Emily Johnson, Sean Ryder
Hnrnp A1 And Secondary Structure Coordinate Alternative Splicing Of Mag, Nancy Zearfoss, Emily Johnson, Sean Ryder
Sean P. Ryder
Myelin-associated glycoprotein (MAG) is a major component of myelin in the vertebrate central nervous system. MAG is present in the periaxonal region of the myelin structure, where it interacts with neuronal proteins to inhibit axon outgrowth and protect neurons from degeneration. Two alternatively spliced isoforms of Mag mRNA have been identified. The mRNA encoding the shorter isoform, known as S-MAG, contains a termination codon in exon 12, while the mRNA encoding the longer isoform, known as L-MAG, skips exon 12 and produces a protein with a longer C-terminal region. L-MAG is required in the central nervous system. How inclusion of …
Argonaute Protein Identity And Pairing Geometry Determine Cooperativity In Mammalian Rna Silencing, Jennifer Broderick, William Salomon, Sean Ryder, Neil Aronin, Phillip Zamore
Argonaute Protein Identity And Pairing Geometry Determine Cooperativity In Mammalian Rna Silencing, Jennifer Broderick, William Salomon, Sean Ryder, Neil Aronin, Phillip Zamore
Sean P. Ryder
Small RNAs loaded into Argonaute proteins direct silencing of complementary target mRNAs. It has been proposed that multiple, imperfectly complementary small interfering RNAs or microRNAs, when bound to the 3' untranslated region of a target mRNA, function cooperatively to silence target expression. We report that, in cultured human HeLa cells and mouse embryonic fibroblasts, Argonaute1 (Ago1), Ago3, and Ago4 act cooperatively to silence both perfectly and partially complementary target RNAs bearing multiple small RNA-binding sites. Our data suggest that for Ago1, Ago3, and Ago4, multiple, adjacent small RNA-binding sites facilitate cooperative interactions that stabilize Argonaute binding. In contrast, small RNAs …
Development And Characterization Of A Severe Acute Respiratory Syndrome-Associated Coronavirus-Neutralizing Human Monoclonal Antibody That Provides Effective Immunoprophylaxis In Mice, Thomas Greenough, Gregory Babcock, Anjeanette Roberts, Hector Hernandez, William Thomas, Jennifer Coccia, Robert Graziano, Mohan Srinivasan, Israel Lowy, Robert Finberg, Kanta Subbarao, Leatrice Vogel, Mohan Somasundaran, Katherine Luzuriaga, John Sullivan, Donna Ambrosino
Development And Characterization Of A Severe Acute Respiratory Syndrome-Associated Coronavirus-Neutralizing Human Monoclonal Antibody That Provides Effective Immunoprophylaxis In Mice, Thomas Greenough, Gregory Babcock, Anjeanette Roberts, Hector Hernandez, William Thomas, Jennifer Coccia, Robert Graziano, Mohan Srinivasan, Israel Lowy, Robert Finberg, Kanta Subbarao, Leatrice Vogel, Mohan Somasundaran, Katherine Luzuriaga, John Sullivan, Donna Ambrosino
William D Thomas Jr
BACKGROUND: Severe acute respiratory syndrome (SARS) remains a significant public health concern after the epidemic in 2003. Human monoclonal antibodies (MAbs) that neutralize SARS-associated coronavirus (SARS-CoV) could provide protection for exposed individuals. METHODS: Transgenic mice with human immunoglobulin genes were immunized with the recombinant major surface (S) glycoprotein ectodomain of SARS-CoV. Epitopes of 2 neutralizing MAbs derived from these mice were mapped and evaluated in a murine model of SARS-CoV infection. RESULTS: Both MAbs bound to S glycoprotein expressed on transfected cells but differed in their ability to block binding of S glycoprotein to Vero E6 cells. Immunoprecipitation analysis revealed …
Translocation Channel Gating Kinetics Balances Protein Translocation Efficiency With Signal Sequence Recognition Fidelity, Steven Trueman, Elisabet Mandon, Reid Gilmore
Translocation Channel Gating Kinetics Balances Protein Translocation Efficiency With Signal Sequence Recognition Fidelity, Steven Trueman, Elisabet Mandon, Reid Gilmore
Elisabet Mandon
The transition between the closed and open conformations of the Sec61 complex permits nascent protein insertion into the translocation channel. A critical event in this structural transition is the opening of the lateral translocon gate that is formed by four transmembrane (TM) spans (TM2, TM3, TM7, and TM8 in Sec61p) to expose the signal sequence-binding site. To gain mechanistic insight into lateral gate opening, mutations were introduced into a lumenal loop (L7) that connects TM7 and TM8. The sec61 L7 mutants were found to have defects in both the posttranslational and cotranslational translocation pathways due to a kinetic delay in …
Structural And Thermodynamic Basis Of Amprenavir/Darunavir And Atazanavir Resistance In Hiv-1 Protease With Mutations At Residue 50, Seema Mittal, Rajintha Bandaranayake, Nancy King, Moses Prabu-Jeyabalan, Madhavi Nalam, Ellen Nalivaika, Nese Yilmaz, Celia Schiffer
Structural And Thermodynamic Basis Of Amprenavir/Darunavir And Atazanavir Resistance In Hiv-1 Protease With Mutations At Residue 50, Seema Mittal, Rajintha Bandaranayake, Nancy King, Moses Prabu-Jeyabalan, Madhavi Nalam, Ellen Nalivaika, Nese Yilmaz, Celia Schiffer
Celia A. Schiffer
Drug resistance occurs through a series of subtle changes that maintain substrate recognition but no longer permit inhibitor binding. In HIV-1 protease, mutations at I50 are associated with such subtle changes that confer differential resistance to specific inhibitors. Residue I50 is located at the protease flap tips, closing the active site upon ligand binding. Under selective drug pressure, I50V/L substitutions emerge in patients, compromising drug susceptibility and leading to treatment failure. The I50V substitution is often associated with amprenavir (APV) and darunavir (DRV) resistance, while the I50L substitution is observed in patients failing atazanavir (ATV) therapy. To explain how APV, …
Identification Of Cytoplasmic Residues Of Sec61p Involved In Ribosome Binding And Cotranslational Translocation, Zhiliang Cheng, Ying Jiang, Elisabet Mandon, Reid Gilmore
Identification Of Cytoplasmic Residues Of Sec61p Involved In Ribosome Binding And Cotranslational Translocation, Zhiliang Cheng, Ying Jiang, Elisabet Mandon, Reid Gilmore
Elisabet Mandon
The cytoplasmic surface of Sec61p is the binding site for the ribosome and has been proposed to interact with the signal recognition particle receptor during targeting of the ribosome nascent chain complex to the translocation channel. Point mutations in cytoplasmic loops six (L6) and eight (L8) of yeast Sec61p cause reductions in growth rates and defects in the translocation of nascent polypeptides that use the cotranslational translocation pathway. Sec61 heterotrimers isolated from the L8 sec61 mutants have a greatly reduced affinity for 80S ribosomes. Cytoplasmic accumulation of protein precursors demonstrates that the initial contact between the large ribosomal subunit and …
Nitric Oxide-Mediated Inhibition Of Hdm2-P53 Binding, Christopher Schonhoff, Marie-Claire Daou, Stephen Jones, Celia Schiffer, Alonzo Ross
Nitric Oxide-Mediated Inhibition Of Hdm2-P53 Binding, Christopher Schonhoff, Marie-Claire Daou, Stephen Jones, Celia Schiffer, Alonzo Ross
Celia A. Schiffer
It has become increasingly evident that nitric oxide exerts its effects, in part, by S-nitrosylation of cysteine residues. We tested in vitro whether nitric oxide may indirectly control p53 by S-nitrosylation and inactivation of the p53 negative regulator, Hdm2. Treatment of Hdm2 with a nitric oxide donor inhibits Hdm2-p53 binding, a critical step in Hdm2 regulation of p53. The presence of excess amounts of cysteine or dithiothreitol blocks this inhibition of binding. Moreover, nitric oxide inhibition of Hdm2-p53 binding was found to be reversible. Sulfhydryl sensitivity and reversibility are consistent with nitrosylation. Finally, we have identified a critical cysteine residue …
Contribution Of Ser386 And Ser396 To Activation Of Interferon Regulatory Factor 3, Weijun Chen, Hema Srinath, Suvana Lam, Celia Schiffer, William Royer, Kai Lin
Contribution Of Ser386 And Ser396 To Activation Of Interferon Regulatory Factor 3, Weijun Chen, Hema Srinath, Suvana Lam, Celia Schiffer, William Royer, Kai Lin
Celia A. Schiffer
IRF-3, a member of the interferon regulatory factor (IRF) family of transcription factors, functions in innate immune defense against viral infection. Upon infection, host cell IRF-3 is activated by phosphorylation at its seven C-terminal Ser/Thr residues: (385)SSLENTVDLHISNSHPLSLTS(405). This phosphoactivation triggers IRF-3 to react with the coactivators, CREB-binding protein (CBP)/p300, to form a complex that activates target genes in the nucleus. However, the role of each phosphorylation site for IRF-3 phosphoactivation remains unresolved. To address this issue, all seven Ser/Thr potential phosphorylation sites were screened by mutational studies, size-exclusion chromatography, and isothermal titration calorimetry. Using purified proteins, we show that CBP …
Adam12 Induces Actin Cytoskeleton And Extracellular Matrix Reorganization During Early Adipocyte Differentiation By Regulating Beta1 Integrin Function, Nobuko Kawaguchi, Christina Sundberg, Marie Kveiborg, Behzad Moghadaszadeh, Meena Asmar, Nikolaj Dietrich, Charles Kumar Thodeti, Finn C. Nielsen, Peter Moller, Arthur M. Mercurio, Reidar Albrechtsen, Ulla M. Wewer
Adam12 Induces Actin Cytoskeleton And Extracellular Matrix Reorganization During Early Adipocyte Differentiation By Regulating Beta1 Integrin Function, Nobuko Kawaguchi, Christina Sundberg, Marie Kveiborg, Behzad Moghadaszadeh, Meena Asmar, Nikolaj Dietrich, Charles Kumar Thodeti, Finn C. Nielsen, Peter Moller, Arthur M. Mercurio, Reidar Albrechtsen, Ulla M. Wewer
Arthur M. Mercurio
Changes in cell shape are a morphological hallmark of differentiation. In this study we report that the expression of ADAM12, a disintegrin and metalloprotease, dramatically affects cell morphology in preadipocytes, changing them from a flattened, fibroblastic appearance to a more rounded shape. We showed that the highest levels of ADAM12 mRNA were detected in preadipocytes at the critical stage when preadipocytes become permissive for adipogenic differentiation. Furthermore, as assessed by immunostaining, ADAM12 was transiently expressed at the cell surface concomitant with the reduced activity of beta1 integrin. Co-immunoprecipitation studies indicated the formation of ADAM12/beta1 integrin complexes in these preadipocytes. Overexpression …
Ethanol-Mediated Regulation Of Transcription Factors In Immunocompetent Cells, Gyongyi Szabo, Pranoti Mandrekar
Ethanol-Mediated Regulation Of Transcription Factors In Immunocompetent Cells, Gyongyi Szabo, Pranoti Mandrekar
Gyongyi Szabo
The immunomodulatory effects of acute and chronic alcohol use are characterized by impaired antigen-specific immune activation and by increased susceptibility to infections due to alterations in innate immune responses and inflammatory mediator production. The central feature of cellular responses to inflammatory and stress signals is the activation of the nuclear regulatory kappa B/Rel family of transcriptional factors via various surface receptor systems in immunocompetent cells. Activation of NF-kappa B, however, is regulated at multiple levels including I-kappa B degradation, nuclear translocation, and by interaction of NF-kappa B/Rel with other transcription factors. Data from our and other laboratories demonstrate that acute …
Supervillin Reorganizes The Actin Cytoskeleton And Increases Invadopodial Efficiency, Jessica Lynn Crowley, Tara C. Smith, Zhiyou Fang, Norio Takizawa, Elizabeth J. Luna
Supervillin Reorganizes The Actin Cytoskeleton And Increases Invadopodial Efficiency, Jessica Lynn Crowley, Tara C. Smith, Zhiyou Fang, Norio Takizawa, Elizabeth J. Luna
Elizabeth J. Luna
Tumor cells use actin-rich protrusions called invadopodia to degrade extracellular matrix (ECM) and invade tissues; related structures, termed podosomes, are sites of dynamic ECM interaction. We show here that supervillin (SV), a peripheral membrane protein that binds F-actin and myosin II, reorganizes the actin cytoskeleton and potentiates invadopodial function. Overexpressed SV induces redistribution of lamellipodial cortactin and lamellipodin/RAPH1/PREL1 away from the cell periphery to internal sites and concomitantly increases the numbers of F-actin punctae. Most punctae are highly dynamic and colocalize with the podosome/invadopodial proteins, cortactin, Tks5, and cdc42. Cortactin binds SV sequences in vitro and contributes to the formation …
Dictyostelium Discoideum Plasma Membranes Contain An Actin-Nucleating Activity That Requires Ponticulin, An Integral Membrane Glycoprotein, A. Shariff, Elizabeth J. Luna
Dictyostelium Discoideum Plasma Membranes Contain An Actin-Nucleating Activity That Requires Ponticulin, An Integral Membrane Glycoprotein, A. Shariff, Elizabeth J. Luna
Elizabeth J. Luna
In previous equilibrium binding studies, Dictyostelium discoideum plasma membranes have been shown to bind actin and to recruit actin into filaments at the membrane surface. However, little is known about the kinetic pathway(s) through which actin assembles at these, or other, membranes. We have used actin fluorescently labeled with N-(1-pyrenyl)iodoacetamide to examine the kinetics of actin assembly in the presence of D. discoideum plasma membranes. We find that these membranes increase the rate of actin polymerization. The rate of membrane-mediated actin polymerization is linearly dependent on membrane protein concentrations up to 20 micrograms/ml. Nucleation (the association of activated actin monomers …
Patellin1, A Novel Sec14-Like Protein, Localizes To The Cell Plate And Binds Phosphoinositides, T. Peterman, Yamini Ohol, Lisa Mcreynolds, Elizabeth Luna
Patellin1, A Novel Sec14-Like Protein, Localizes To The Cell Plate And Binds Phosphoinositides, T. Peterman, Yamini Ohol, Lisa Mcreynolds, Elizabeth Luna
Elizabeth J. Luna
Membrane trafficking is central to construction of the cell plate during plant cytokinesis. Consequently, a detailed understanding of the process depends on the characterization of molecules that function in the formation, transport, targeting, and fusion of membrane vesicles to the developing plate, as well as those that participate in its consolidation and maturation into a fully functional partition. Here we report the initial biochemical and functional characterization of patellin1 (PATL1), a novel cell-plate-associated protein that is related in sequence to proteins involved in membrane trafficking in other eukaryotes. Analysis of the Arabidopsis genome indicated that PATL1 is one of a …
Supervillin (P205): A Novel Membrane-Associated, F-Actin-Binding Protein In The Villin/Gelsolin Superfamily, Kersi N. Pestonjamasp, Robert K. Pope, J. D. Wulfkuhle, Elizabeth J. Luna
Supervillin (P205): A Novel Membrane-Associated, F-Actin-Binding Protein In The Villin/Gelsolin Superfamily, Kersi N. Pestonjamasp, Robert K. Pope, J. D. Wulfkuhle, Elizabeth J. Luna
Elizabeth J. Luna
Actin-binding membrane proteins are involved in both adhesive interactions and motile processes. We report here the purification and initial characterization of p205, a 205-kD protein from bovine neutrophil plasma membranes that binds to the sides of actin filaments in blot overlays. p205 is a tightly bound peripheral membrane protein that cosediments with endogenous actin in sucrose gradients and immunoprecipitates. Amino acid sequences were obtained from SDS-PAGE-purified p205 and used to generate antipeptide antibodies, immunolocalization data, and cDNA sequence information. The intracellular localization of p205 in MDBK cells is a function of cell density and adherence state. In subconfluent cells, p205 …
Smooth Muscle Archvillin: A Novel Regulator Of Signaling And Contractility In Vascular Smooth Muscle, Samudra S. Gangopadhyay, Norio Takizawa, Cynthia Gallant, Amy L. Barber, Hyun-Dong Je, Tara C. Smith, Elizabeth J. Luna, Kathleen G. Morgan
Smooth Muscle Archvillin: A Novel Regulator Of Signaling And Contractility In Vascular Smooth Muscle, Samudra S. Gangopadhyay, Norio Takizawa, Cynthia Gallant, Amy L. Barber, Hyun-Dong Je, Tara C. Smith, Elizabeth J. Luna, Kathleen G. Morgan
Elizabeth J. Luna
The mechanisms by which protein kinase C (PKC) and extracellular-signal-regulated kinases (ERK1/2) govern smooth-muscle contractility remain unclear. Calponin (CaP), an actin-binding protein and PKC substrate, mediates signaling through ERK1/2. We report here that CaP sequences containing the CaP homology (CH) domain bind to the C-terminal 251 amino acids of smooth-muscle archvillin (SmAV), a new splice variant of supervillin, which is a known actin- and myosin-II-binding protein. The CaP-SmAV interaction is demonstrated by reciprocal yeast two-hybrid and blot-overlay assays and by colocalization in COS-7 cells. In differentiated smooth muscle, endogenous SmAV and CaP co-fractionate and co-translocate to the cell cortex after …
Supervillin Modulation Of Focal Adhesions Involving Trip6/Zrp-1, Norio Takizawa, Tara C. Smith, Thomas Nebl, Jessica Lynn Crowley, Stephen J. Palmieri, Lawrence M. Lifshitz, Anka G. Ehrhardt, Laura M. Hoffman, Mary C. Beckerle, Elizabeth J. Luna
Supervillin Modulation Of Focal Adhesions Involving Trip6/Zrp-1, Norio Takizawa, Tara C. Smith, Thomas Nebl, Jessica Lynn Crowley, Stephen J. Palmieri, Lawrence M. Lifshitz, Anka G. Ehrhardt, Laura M. Hoffman, Mary C. Beckerle, Elizabeth J. Luna
Elizabeth J. Luna
Cell-substrate contacts, called focal adhesions (FAs), are dynamic in rapidly moving cells. We show that supervillin (SV)--a peripheral membrane protein that binds myosin II and F-actin in such cells--negatively regulates stress fibers, FAs, and cell-substrate adhesion. The major FA regulatory sequence within SV (SV342-571) binds to the LIM domains of two proteins in the zyxin family, thyroid receptor-interacting protein 6 (TRIP6) and lipoma-preferred partner (LPP), but not to zyxin itself. SV and TRIP6 colocalize within large FAs, where TRIP6 may help recruit SV. RNAi-mediated decreases in either protein increase cell adhesion to fibronectin. TRIP6 partially rescues SV effects on stress …
F-Actin And Myosin Ii Binding Domains In Supervillin, Yu Chen, Norio Takizawa, Jessica Crowley, Sang Oh, Cheryl Gatto, Taketoshi Kambara, Osamu Sato, Xiang-Dong Li, Mitsuo Ikebe, Elizabeth Luna
F-Actin And Myosin Ii Binding Domains In Supervillin, Yu Chen, Norio Takizawa, Jessica Crowley, Sang Oh, Cheryl Gatto, Taketoshi Kambara, Osamu Sato, Xiang-Dong Li, Mitsuo Ikebe, Elizabeth Luna
Elizabeth J. Luna
Detergent-resistant membranes contain signaling and integral membrane proteins that organize cholesterol-rich domains called lipid rafts. A subset of these detergent-resistant membranes (DRM-H) exhibits a higher buoyant density ( approximately 1.16 g/ml) because of association with membrane skeleton proteins, including actin, myosin II, myosin 1G, fodrin, and an actin- and membrane-binding protein called supervillin (Nebl, T., Pestonjamasp, K. N., Leszyk, J. D., Crowley, J. L., Oh, S. W., and Luna, E. J. (2002) J. Biol. Chem. 277, 43399-43409). To characterize interactions among DRM-H cytoskeletal proteins, we investigated the binding partners of the novel supervillin N terminus, specifically amino acids 1-830. We …
The Integral Membrane Protein, Ponticulin, Acts As A Monomer In Nucleating Actin Assembly, C. P. Chia, A. Shariff, S. A. Savage, Elizabeth J. Luna
The Integral Membrane Protein, Ponticulin, Acts As A Monomer In Nucleating Actin Assembly, C. P. Chia, A. Shariff, S. A. Savage, Elizabeth J. Luna
Elizabeth J. Luna
Ponticulin, an F-actin binding transmembrane glycoprotein in Dictyostelium plasma membranes, was isolated by detergent extraction from cytoskeletons and purified to homogeneity. Ponticulin is an abundant membrane protein, averaging approximately 10(6) copies/cell, with an estimated surface density of approximately 300 per microns2. Ponticulin solubilized in octylglucoside exhibited hydrodynamic properties consistent with a ponticulin monomer in a spherical or slightly ellipsoidal detergent micelle with a total molecular mass of 56 +/- 6 kD. Purified ponticulin nucleated actin polymerization when reconstituted into Dictyostelium lipid vesicles, but not when a number of commercially available lipids and lipid mixtures were substituted for the endogenous lipid. …
F-Actin Binds To The Cytoplasmic Surface Of Ponticulin, A 17-Kd Integral Glycoprotein From Dictyostelium Discoideum Plasma Membranes, L. J. Wuestehube, Elizabeth J. Luna
F-Actin Binds To The Cytoplasmic Surface Of Ponticulin, A 17-Kd Integral Glycoprotein From Dictyostelium Discoideum Plasma Membranes, L. J. Wuestehube, Elizabeth J. Luna
Elizabeth J. Luna
F-actin affinity chromatography and immunological techniques are used to identify actin-binding proteins in purified Dictyostelium discoideum plasma membranes. A 17-kD integral glycoprotein (gp17) consistently elutes from F-actin columns as the major actin-binding protein under a variety of experimental conditions. The actin-binding activity of gp17 is identical to that of intact plasma membranes: it resists extraction with 0.1 N NaOH, 1 mM dithiothreitol (DTT); it is sensitive to ionic conditions; it is stable over a wide range of pH; and it is eliminated by proteolysis, denaturation with heat, or treatment with DTT and N-ethylmaleimide. gp17 may be responsible for much of …