Free L-phosphotyrosine activates human platelets: molecular evidence for a new signal transducer.
Human platelets, either purified or plasma-enriched, are activated when exposed to free L-phosphotyrosine. Physical aggregation is similar to that induced by collagen, although with distinctive biochemical features. Among these, a mobility shift of a GTP-binding protein specifically recognized by an anti-Ki-v-ras monoclonal antibody and an altered pattern of low molecular weight phosphorylated polypeptides are the most outstanding features. Since free phosphotyrosine is detected in platelets extracts, its role as a new signal transducer as well as its putative modulating action over protein phosphorylation are discussed.
D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D001798:Blood Proteins / Q000302:isolation & purification / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D015689:Oncogene Protein p21(ras) / Q000097:blood / Q000276:immunology / Q000302:isolation & purification; D010750:Phosphoproteins / Q000097:blood / Q000302:isolation & purification; D010766:Phosphorylation; D019000:Phosphotyrosine; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation; D015398:Signal Transduction; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D001798:Blood Proteins; D010750:Phosphoproteins; D019000:Phosphotyrosine; D014443:Tyrosine; D019204:GTP-Binding Proteins; D015689:Oncogene Protein p21(ras)