When rabbit platelets were stimulated by platelet-activating factor (PAF), phosphatidylinositol disappeared rapidly and diacylglycerol was transiently accumulated. Concurrently, an endogenous protein with a molecular weight of about 40,000 (40K protein) was heavily phosphorylated and serotonin was released. These PAF-induced reactions were associated with one another, and simultaneously inhibited by prostaglandin E1 and dibutyryl cyclic AMP. Fingerprint analysis of the phosphorylation sites in 40K protein suggested that Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C) was responsible for the phosphorylation of 40K protein. PAF did not appear to activate protein kinase C directly. It is likely that PAF causes the release of serotonin in a mechanism analogous to the thrombin action through its receptor-mediated activation of this unique protein kinase system.
|Number of pages
|Biochemical and Biophysical Research Communications
|Published - 29-10-1982
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology