Differential capacities of the RGS1, RGS16 and RGS–GAIP regulators of G protein signaling to enhance α2A‐adrenoreceptor agonist‐stimulated GTPase activity of Go1α

摘要: Recombinant RGS1, RGS16 and RGS–GAIP, but not RGS2, were able to substantially further stimulate the maximal GTPase activity of Go1α promoted by agonists at α2A-adrenoreceptor in a concentration-dependent manner. Kinetic analysis regulation an α2A-adrenoreceptor–Go1α fusion protein all three RGS proteins revealed that they had similar affinities for receptor–G protein fusion. However, their effects on GTP hydrolysis varied over threefold with RGS16 > RGS1 > RGS–GAIP. Both RGS1 reduced potency agonist adrenaline some 10-fold. A lower shift was observed partial UK14304 effect absent weak oxymetazoline. Each these altered intrinsic both oxymetazoline relative adrenaline. Such results require interaction alter conformation are thus consistent models invoking direct interactions between receptors. These studies demonstrate RGS–GAIP show high degree selectivity regulate α2A-adrenoreceptor-activated rather than Gi1α, Gi2α or Gi3α different capacities inactivate this G protein.