Multiple Messenger Roles for the Inhibitory GTP-Binding Protein, Gi, in Human Platelets
The cellular events which are necessary for transducing signals from the binding of an agonist with its surface membrane receptor to the final cellular response are still much of a mystery. One particular class of receptors stimulates cells by inducing a rise in the cytosolic Ca + concentration and also by activating protein kinase C. To achieve this, the agonist-occupied receptor stimulates phospholipase C which hydrolyses inositol phospholipids, particularly phosphatidylinositol-4,5-bisphosphate. The result is the generation of the second messenger molecules inositol 1,4,5-trisphosphate and 1,2-diacylglycerol, which release intracellular Ca + stores and activate protein kinase C., respectively (Berridge, 1987).
KeywordsAdenylate Cyclase Human Platelet Pertussis Toxin Thrombin Receptor Inhibit Adenylate Cyclase
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