Fig. 4.
Growth hormone secretagogues and growth hormone releasing peptides do not alter the EMAX of ghrelin to activate of Gαo1 via the ghrelin receptor; [35S]GTPγS binding experiments were performed on membranes of HEK293 cells transfected to coexpress Gαo1 and the ghrelin receptor. Data points represent the mean ± S.E.M of three independent experiments performed in triplicate. Data were fitted to eq. 2. Data are shown fitted with αβ = 0 and the slope transducer function constrained to 1. A, a series of concentration-response curves to ghrelin was performed in the absence (control) or presence of varying concentrations of MK-677 (as indicated). B, equivalent studies were performed with ghrelin and varying concentrations of GHRP-6. C, equivalent studies were performed with ghrelin and varying concentrations of L-692,585.