Phosphorylation of rap1B by protein kinase a is not involved in platelet inhibition by cyclic AMP
1993; Elsevier BV; Volume: 5; Issue: 2 Linguagem: Inglês
10.1016/0898-6568(93)90071-s
ISSN1873-3913
AutoresWolfgang Siess, Bernd Grünberg,
Tópico(s)Blood Coagulation and Thrombosis Mechanisms
ResumoThe functional consequence of cyclic AMP-dependent phosphorylation of rap1B for stimulus-induced platelet activation is not known. Platelets were pretreated with the stable prostacyclin-analogue iloprost and resuspended in plasma without iloprost. Western blot analysis showed that rap1B was completely converted into its phosphorylated form in the iloprost-pretreated platelets. Surprisingly, the platelets that contained phosphorylated rap1B were found to respond fully to activation by a wide variety of stimuli: aggregation upon stimulation by collagen, phorbol ester, vasopressin, ADP, epinephrine, and ATP-secretion from dense granules induced by collagen, thrombin-receptor activating peptide, vasopressin and phorbol ester were unchanged as compared to control. The results indicate that cyclic AMP-dependent phosphorylation of rap1B does not play a role in the inhibition of the various signal transduction pathways that lead to platelet aggregation and dense granule secretion.
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