title: Collagen stimulates tyrosine phosphorylation of phospholipase C-gamma 2 but not phospholipase C-gamma 1 in human platelets.
abstract: Collagen is an important primary stimulus of platelets during the process of hemostasis. As with many other platelet stimuli, collagen signal transduction involves the hydrolysis of inositol phospholipids; however, the mechanisms which underlies this event is not well understood. Neither the collagen receptor nor the isoform of phospholipase C that is activated have been identified. We report that collagen-activation of platelets induces tyrosine phosphorylation of phospholipase C-gamma 2 but not phospholipase C-gamma 1. We also show that the platelet low affinity Fc receptor (Fc gamma RII), which mediates activation of platelets by immune complexes, and wheat germ agglutinin, which binds non-specifically to glycoprotein, stimulate phospholipase C-gamma 2 tyrosine phosphorylation. In contrast, we could not detect phospholipase C-gamma 2 tyrosine phosphorylation in platelets stimulated by either thrombin or a stable thromboxane A2 analogue, U46619.
authors.affiliation: Department of Pharmacology, Oxford, UK.
authors.forename: R A
authors.initials: RA
authors.lastname: Blake
authors.forename: G L
authors.initials: GL
authors.lastname: Schieven
authors.forename: S P
authors.initials: SP
authors.lastname: Watson
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D002118:Calcium / Q000097:blood; D003094:Collagen / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D007163:Immunosorbent Techniques; D010766:Phosphorylation; D019000:Phosphotyrosine; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011961:Receptors, Fc / Q000502:physiology; D013917:Thrombin / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D010738:Type C Phospholipases / Q000097:blood*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000097:blood; D014909:Wheat Germ Agglutinins / Q000494:pharmacology
chemical_list: D011450:Prostaglandin Endoperoxides, Synthetic; D011961:Receptors, Fc; D014909:Wheat Germ Agglutinins; D019000:Phosphotyrosine; D014443:Tyrosine; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D003094:Collagen; D011493:Protein Kinase C; D010738:Type C Phospholipases; D013917:Thrombin; D002118:Calcium