Zn2+ enhances protein tyrosine kinase activity of human platelet membranes.
In human platelet membranes enhanced tyrosine phosphorylation of certain proteins was observed when Zn2+ instead of Mg2+ or Mn2+ was used as a divalent cation for the kinase reaction. An enhanced level of phosphate incorporation into tyrosine residues occurred into a 68 kDa polypeptide besides the 45 kDa and 105 kDa proteins. Preincubation of platelet membranes with TBR-IgG showed a concentration-dependent inhibition of the phosphorylation of the 45, 68 and 105 kDa proteins. Moreover, pp60c-src, representing the major protein tyrosine kinase activity in platelets, was found to be stimulated by Zn2+. The data, thus, support the assumption that pp60c-src kinase is responsible for Zn2+ stimulated tyrosine phosphorylation.
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Rudolf Buchheim-Institut für Pharmakologie, Justus Liebig-Universität, Giessen, FRG.
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D001792:Blood Platelets / Q000201:enzymology*; D002413:Cations, Divalent; D002462:Cell Membrane / Q000201:enzymology; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D010766:Phosphorylation; D019000:Phosphotyrosine; D011494:Protein Kinases / Q000097:blood; D011505:Protein-Tyrosine Kinases / Q000097:blood*; D011518:Proto-Oncogene Proteins / Q000097:blood; D016392:Proto-Oncogene Proteins pp60(c-src); D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology*
D002413:Cations, Divalent; D011518:Proto-Oncogene Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D008345:Manganese; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); D008274:Magnesium; D015032:Zinc