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Polyphosphoinositide synthesis in platelets stimulated with low concentrations of thrombin is enhanced before the activation of phospholipase C
Author(s) -
Lassing Ingrid,
Lindberg Uno
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80197-q
Subject(s) - phosphatidylinositol , phosphatidic acid , diacylglycerol kinase , phospholipase c , second messenger system , phospholipid , chemistry , biochemistry , thrombin , phospholipase d , stimulation , kinase , platelet , phosphatidate , phosphorylation , platelet activation , phospholipase , receptor , diglyceride , signal transduction , protein kinase c , medicine , biology , endocrinology , enzyme , membrane
When platelets, prelabelled with [ 32 P]orthophosphate, were stimulated with thrombin (0.5 U·ml −1 ) there was an immediate increase in the radioactivity associated with the pools of polyphosphoinositides. Only subsequent to this increase, did the radioactivity of these phospholipid pools decrease as expected from a receptor‐mediated activation of phospholipase C (phosphoinositidase). Phosphorylation of diacylglycerol (one of the second messengers formed in the hydrolysis of phosphatidylinositol‐bisphosphate) to phosphatidic acid took place with a lag phase of about 3–5 s. Together these experiments suggest that stimulation of kinases phosphorylating phosphatidylinositol and phosphatidylinositol‐phosphate may precede or occur in parallel with activation of receptor‐linked phosphoinositidase.