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This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Polanowska-Grabowska, R. Articles by Gear, A. R.L. Search for Related Content PubMed PubMed Citation Articles by Polanowska-Grabowska, R. Articles by Gear, A. R.L. Related Collections Hemostasis, Thrombosis, and Vascular Biology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Platelet Adhesion to Collagen Under Flow Causes Dissociation of a Phosphoprotein Complex of Heat-Shock Proteins and Protein Phosphatase 1  Renata Polanowska-Grabowska, Carl G. Simon Jr, Rocco Falchetto, Jeffrey Shabanowitz, Donald F. Hunt, and Adrian R.L. Gear From the Departments of Biochemistry, Chemistry, and Pathology, University of Virginia, Charlottesville, VA. Phosphorylation/dephosphorylation events in human blood platelets were investigated during their adhesion to collagen under flow conditions. Using 32P-labeled platelets and one-dimensional gel electrophoresis, we found that adhesion to collagen mediated primarily by the 21 integrin resulted in a strong dephosphorylation of several protein bands. Neither adhesion to polylysine nor thrombin-induced aggregation caused similar protein dephosphorylation. In addition, treatment with okadaic acid (OA), an inhibitor of serine/threonine protein phosphatases type 1 (PP1) and 2A (PP2A), caused significant inhibition of adhesion, suggesting that adhesion is regulated by OA-sensitive phosphatases. Recent studies indicate that phosphatases may be associated with the heat-shock proteins. Immunoprecipitations with antibodies against either the heat-shock cognate protein 70 (hsc70) or heat-shock protein 90 (hsp90) showed the presence of a phosphoprotein complex in 32P-labeled, resting human platelets. Antibody probing of this complex detected hsc70, hsp90, two isoforms of the catalytic subunit of PP1, PP1C and PP1C, as well as the M regulatory subunit of PP1 (PP1M). OA, at concentrations that markedly blocked platelet adhesion to collagen, caused hyperphosphorylation of the hsc70 complex. In platelets adhering to collagen, hsc70 was completely dephosphorylated and hsp90, PP1, and PP1M were dissociated from the complex, suggesting involvement of heat-shock proteins and protein phosphatases in platelet adhesion. Blood, Vol. 90 No. 4 (August 15), 1997: pp. 1516-1526 © 1997 by The American Society of Hematology. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: R. E. Feaver, N. E. Hastings, A. 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