title: K252a, a new inhibitor of protein kinase C, concomitantly inhibits 40K protein phosphorylation and serotonin secretion in a phorbol ester-stimulated platelets.
abstract: K252a isolated from microbial origin was found to potently inhibit protein kinase C in vitro (1). This agent inhibits phosphorylation of 40,000 dalton protein (40K protein) induced by 12-0-tetradecanoylphorbol-13-acetate(TPA) in intact rabbit platelets. This indicates that K252a exhibits the inhibition of protein kinase C in intact cells. The serotonin secretion induced by TPA was inhibited by K252a at nearly equal concentrations required to inhibit the phosphorylation of 40K protein. This provides the evidence to support the cause-effect relationship between the protein phosphorylation and the secretion in TPA-stimulated platelets.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D002227:Carbazoles / Q000494:pharmacology*; D066298:In Vitro Techniques; D026121:Indole Alkaloids; D008297:Male; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D011817:Rabbits; D012701:Serotonin / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D002227:Carbazoles; D026121:Indole Alkaloids; D012701:Serotonin; D000255:Adenosine Triphosphate; C049985:staurosporine aglycone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate