title: Tyrosine-specific protein phosphorylation is regulated by glycoprotein IIb-IIIa in platelets.
abstract: We have previously shown that a number of platelet proteins become phosphorylated at tyrosine residues in response to platelet-activating agents. Here we present two lines of evidence implicating a platelet integrin, glycoprotein IIb-IIIa, in the regulation of a specific subset of these tyrosine phosphorylations. (i) Two peptides that inhibit the binding of fibrinogen and other ligands to gpIIb-IIIa, Arg-Gly-Asp-Ser and His-His-Leu-Gly-Gly-Ala-Lys-Gln-Ala-Gly-Asp-Val, also inhibited the thrombin-induced tyrosine phosphorylation of this subset of proteins. The tetrapeptide Arg-Gly-Glu-Ser, which does not inhibit fibrinogen binding, did not inhibit thrombin-stimulated tyrosine phosphorylation. (ii) Platelets lacking gpIIb-IIIa (from a subject with Glanzmann thrombasthenia) did not undergo this subset of tyrosine phosphorylation in response to thrombin, although other serine, threonine, and tyrosine phosphorylations proceeded normally. These findings suggest a role for tyrosine-specific protein phosphorylation in integrin-mediated cell-matrix recognition.
authors.affiliation: Department of Zoology, University of California, Berkeley 94720.
authors.forename: J E
authors.initials: JE
authors.lastname: Ferrell
authors.forename: G S
authors.initials: GS
authors.lastname: Martin
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000097:blood*; D013917:Thrombin / Q000502:physiology; D014443:Tyrosine
chemical_list: D009842:Oligopeptides; D010980:Platelet Membrane Glycoproteins; D014443:Tyrosine; D000244:Adenosine Diphosphate; D011505:Protein-Tyrosine Kinases; D013917:Thrombin