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Activation of protein kinase C alters the interaction of α 2 ‐adrenoceptors and the inhibitory GTP‐binding protein (G i ) in human platelets
Author(s) -
García-Sáinz J.Adolfo,
Gutiérrez-Venegas Gloria
Publication year - 1989
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(89)81588-1
Subject(s) - gtp' , platelet , inhibitory postsynaptic potential , g protein , chemistry , protein kinase a , gtp binding protein regulators , platelet activation , microbiology and biotechnology , receptor , biochemistry , kinase , biophysics , biology , enzyme , neuroscience , immunology
The effect of 12‐tetradecanoyl phorbol 13‐acetate (TPA) on the hormonal modulation of adenylate cyclase was studied. The effect of epinephrine (α 2 ‐adrenergic action) was markedly diminished in membranes from TPA‐treated platelets as compared to the controls. Interestingly, the inhibitory effect of guanylyl imido diphosphate (Gpp(NH)p) was not altered. Neither the number of α 2 ‐adrenoceptors nor their affinity for [ 3 H]yohimbine were affected by the treatment with TPA. In control platelets, 77% of the receptors were in a high‐affinity state for epinephrine and 22% in a low‐affinity state; Gpp(NH)p shifted the receptor affinity towards the low‐affinity conformation. In membranes from TPA‐treated platelets, the receptors were in the low‐affinity state and no further decrease in affinity was induced by Gpp(NH)p. Our data suggest that activation of protein kinase C in platelets blocks the hormonal inhibition of adenylate cyclase by interfering with the receptor‐G i interaction.