Voltage‐dependent calcium channel β‐subunits in combination with α1 subunits, have a GTPase activating effect to promote the hydrolysis of GTP by Gαo in rat frontal cortex

Abstract
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.