Thrombin activation of human platelets causes tyrosine phosphorylation of PLC-gamma 2.
Human platelets contain phospholipase C (PLC)-gamma 2, a distinct isoform closely related to PLC-gamma 1. Both inositol phospholipid-specific phospholipases C contain the src-related SH2 regions. Stimulation of platelets with the potent agonist, thrombin, led to a rapid and transient phosphorylation of PLC-gamma 2 on tyrosine residues. Activated platelets lysed in the absence of sodium orthovanadate had levels of tyrosine-phosphorylated PLC-gamma 2 paralleling those seen in unstimulated platelets. Previously, it had been shown that PLC-gamma 1 was phosphorylated on tyrosine residues by the agonist-occupied platelet-derived growth factor (PDGF) receptor and epidermal growth factor (EGF) receptor in cells other than platelets. In addition, more recent data have indicated that PLC-gamma 2 is also capable of being tyrosine-phosphorylated in cells of hematopoietic origin, such as B cells and natural killer (NK) cells. Here we report that PLC-gamma 2 expressed in a terminally-differentiated hematopoietic cell is also tyrosine-phosphorylated in response to an agonist.
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Department of Toxicology, Hoffmann-La Roche Inc., Nutley, NJ.
Rittenhouse
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D000906:Antibodies / Q000276:immunology; D001792:Blood Platelets / Q000201:enzymology*; D003429:Cross Reactions; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine; D015539:Platelet Activation / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000276:immunology / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000096:biosynthesis
D000906:Antibodies; D007527:Isoenzymes; D019000:Phosphotyrosine; D014443:Tyrosine; D010738:Type C Phospholipases; D013917:Thrombin