PIP_3 inhibition of RGS protein and its reversal by Ca~2+/calmodulin mediate voltage-dependent control of the G protein cycle in a cardiac K~+ channel

摘要

Regulators of G protein signaling (RGS) accelerate intrinsic GTP hydrolysis onα subunits of trimeric G proteins and play crucial roles in the physiological regulation of G protein-mediated cell signal- ing. The control mechanisms of the action of RGS proteins per se are poorly clarified, however. We recently showed a physiological mode of action of a RGS protein in cardiac myocytes. The voltage- dependent formation of Ca~2+/calmodulin facilitated the GTPase activity of RGS by an unidentified mechanism, which underlay the "relaxation" behavior of G protein-gated K~+ (K_G) channels.