Figure 6.
APJ : AT1 heterodimerization antagonizes AT1 function. (A) Inhibition of Gαq signalling pathway of AT1 by Ap13-activated APJ. Inositol-1-Phosphate (IP1) production was measured using CHO-K1-APJ : AT1 cells stably and equivalently expressing AT1 and APJ receptors in the presence of Ang II (0–2.5 μM) alone or in the presence of a fixed concentration of Ap13. (B) Inhibition of β-arrestin recruitment to AT1 by Ap13-activated APJ. PathHunter AT1 β-Arrestin EFC cells were transfected with pHA-APJ and incubated with Ang II (0.0–100 μM) alone or with a fixed concentration of Ap13. Each symbol represents the mean percent activation of AT1 ± SEM (n = 6) by Ang II at the indicated concentration. In both panels, curves represent the best global fit of the operation model of allosterism as determined using Equation 4.