β-Adrenergic receptors and the inhibitory GTP-binding protein, G(i) of the adenylate cyclase system were reconstituted into phospholipid vesicles by the method described previously for reconstituting receptors and the stimulatory GTP-binding protein G(s) (Brandt, D.R., Asano, T., Pedersen, S.E., and Ross, E.M. (1983) Biochemistry 22, 4357-4362). In the receptor-G(i) vesicles, β-adrenergic agonists stimulated both the high-affinity binding of guanosine 5'-O-(3-thiotriphosphate) (GTPγS) to G(i) and GTPase activity to an extent similar to that observed in vesicles containing β-adrenergic receptors and G(s). Stimulation required receptors and displayed appropriate β-adrenergic specificity. The prior treatment of receptor-G(i) vesicles with islet-activating protein (pertussis toxin) plus NAD markedly inhibited both the isoproterenol-stimulated binding of GTPγS and the isoproterenol-stimulated GTPase activity. No contamination of G(i) by G(s) was apparent. These data suggest that receptors that typically stimulate adenylate cyclase activity may also activate the inhibitory system, perhaps as one mechanism of desensitization.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|State||Published - Jan 1 1984|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology