Mild proteolytic treatment of human platelet membranes by alpha-chymotrypsin increased basal adenylate cyclase activity and abolished the inhibition induced by epinephrine in the presence of GTP. This treatment did not alter the total number of yohimbine binding sites, but markedly decreased the proportion of high affinity, GTP-sensitive sites for epinephrine as assessed from epinephrine competition studies. The effect of proteolysis was dose-dependent upon both adenylate cyclase inhibition and alpha2-adrenergic binding sites, with a half-maximal effect occurring at similar alpha-chymotrypsin concentration. These results support the concept that only one protein is responsible for the GTP regulation of receptor and inhibition of cyclase.
|Number of pages||7|
|Journal||Biochemical and biophysical research communications|
|Publication status||Published - Sep 30 1982|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology