Biochemical characterization of three stimulatory GTP-binding proteins. The large and small forms of Gs and the olfactory-specific G-protein, Golf.

摘要: The biochemical properties of three stimulatory guanine nucleotide-binding protein (G-protein) alpha subunits, the large and small forms Gs, Gs-l (52 kDa) Gs-s (45 kDa), olfactory specific G-protein, Golf, have been compared. Complementary DNAs (cDNAs) encoding each subunit were independently expressed in a mammalian cell line deficient endogenous G-proteins (S49 cyc-kin-). respond similarly to activation by beta-adrenergic agonist isoproterenol (EC50 = 80 60 nM, respectively) receptor-independent G-protein activators guanosine 5-O-3-(thio)triphosphate) (GTP gamma S) AlF-4. ability Golf interact with receptor was also examined. Surprisingly, interacts receptors is activated 120 nM). All treatment different alpha, beta, thiophosphoryl analogs GTP. Specifically, (R)-GTP S GTP activate whereas (S)-GTP (R)- or beta are inactive. In addition, similar Gs covalently modified constitutively cholera toxin. These studies demonstrate that all functionally structurally similar, however, subtle differences between two appear modulate their interactions receptors.