Activated phosphoinositide 3-kinase associates with membrane skeleton in thrombin-exposed platelets

摘要: Human platelets undergo a rapid, major reorganization of the cytoskeletal matrix upon exposure to thrombin, and accumulate 3-phosphorylated phosphoinositides in protein kinase C (PKC)-dependent manner. These have been suggested be involved actin polymerization/depolymerization. We reasoned that, if newly generated phosphoinositide modulates reorganization, prerequisite for such action would generation near proteins. found after platelet activation, phosphatidylinositol 3-kinase phosphatidylinositol(4)P activities, antibody-detectable 3-kinase, PKC become markedly specifically enriched Triton X-100-insoluble fraction that contains GPIIb/IIIa (integrin) pp60c-src. The then accounts up 70% total activity, function recruited activated enzyme. proteins are not occluded or directly associated with polymerized actin, since blockage by cytochalasin D polymerization, consequent inhibition accumulation about 40% incremental this fraction, has no effect on its content GPIIb/IIIa, pp60c-src, PKC. Depolymerization DNase I, ligand binding RGDS, however, combination D, further depletes significantly decreases sedimentability as well PKC, without inhibiting activity. Our results suggest enzymes regulate synthesis rapidly associate membrane skeleton skeletally is more active than Triton-soluble form.