The dihydropyridine-sensitive calcium channel agonist (−)-BayK 8644 was found to produce an enhancement of the intrinsic hydrolysis of GTP by Go in rat frontal cortex membranes. An anti-calcium channel β-subunit antiserum abolished the (−)-BayK 8644-stimulated hydrolysis of GTP by Go and reduced the dihydropyridine binding capacity of the cortical membranes. A peptide which mimics the β-subunit binding domain of the calcium channel complex, also attenuated (−)-BayK 8644 activation of GTPase. This study suggests that the calcium channel β-subunit is the principal component of the channel complex involved in linking dihydropyridine agonist binding to enhanced hydrolysis of GTP by Go. This may be a mechanism by which calcium channels can normally act to limit the duration of a G-protein modulatory signal.
