Coupling of adenosine A1 receptors to a G-protein in coated vesicles isolated from bovine brain: Presence of pertussis and cholera toxin substrates

Abstract

Adenosine A₁ receptors have been described in coated vesicles isolated from bovine brain (Gonzalez-Calero et al., J. Neurochem. 1990, , 106–113). Addition of non hydrolyzable GTP analogue (guanyl-5-yl-imidodiphosphate) caused a transition of the receptor from the high- to the low-affinity state, without any significant change in the total binding sites. The presence of G-proteins has been investigated by pertussis and cholera toxins catalyzed ADP-ribosylation. A band of Mr=41,000 D, similar to the αGi subunit, was specifically labeled in the presence of preactivated pertussis toxin. Bands of Mr=42,000 D and Mr=47,000 D were specifically labeled in the presence of preactivated cholera toxin. These results confirm the presence of GTP binding proteins (αGi and αCs) in coated vesicles isolated from bovine brain.