VOLTAGE-DEPENDENT CALCIUM-CHANNEL BETA-SUBUNITS IN COMBINATION WITH ALPHA(1) SUBUNITS, HAVE A GTPASE-ACTIVATING EFFECT TO PROMOTE THE HYDROLYSIS OF GTP BY G-ALPHA(O) IN RAT FRONTAL-CORTEX

The dihydropyridine-sensitive calcium channel agonist (-)-BayK 8644 wa s found to produce an enhancement of the intrinsic hydrolysis of GTP b y G(0) in rat frontal cortex membranes, An anti-calcium channel beta-s ubunit antiserum abolished the (-)-BayK 8644-stimulated hydrolysis of GTP by G(0) and reduced the dihydropyridine binding capacity of the co rtical membranes, A peptide which mimics the beta-subunit binding doma in of the calcium channel complex, also attenuated (-)-BayK 8644 activ ation of GTPase, This study suggests that the calcium channel beta-sub unit is the principal component of the channel complex involved in lin king dihydropyridine agonist binding to enhanced hydrolysis of GTP by G(0). This may be a mechanism by which calcium channels can normally a ct to limit the duration of a G-protein modulatory signal.