Functional analysis of a human Al adenosine receptor/green fluorescent protein/Gilα fusion protein following stable expression in CHO cells

Fusion proteins between the human A(1) adenosine receptor and the pertussis toxin resistant (Cys351Gly) mutant of the G-protein alpha subunit G(i1) alpha(A1/Gi), and between the human A(1) adenosine receptor, the Aequorea victoria green fluorescent protein (GFP) and Cys351Gly G(i1) alpha. (A1/GFP/Gi), were expressed in CHO cells. The agonist NECA caused a stimulation of [S-35]GTP gamma S binding at both fusion proteins with similar concentration dependence as at the native receptor. However in the presence of pertussis toxin NECA stimulation of [S-35]GTP gamma S binding was only seen at the A1/GFP/Gi fusion protein. The regulation of the adenylyl cyclase and MAP kinase effector systems by both fusion proteins was attenuated following pertussis toxin treatment, These studies demonstrate for the first time the characterisation of a fusion protein between a G-protein coupled receptor, GFP and a G-protein a subunit. (C) 1999 Federation of European Biochemical Societies.