Figure 2.

Linear time course profile examples of GPCR signaling. In all cases, regulation of signaling activity (receptor desensitization and response degradation) was minimized as described in the text boxes. (a) Inositol phosphates production via the AT₁ receptor stimulated by 100 nM AngII in fibroblasts from arrestin knock-out mice (from Fig. 3c of⁴⁰). (b) Inositol phosphates production via the GnRH₁ receptor stimulated by 1 μM GnRH in HEK293 cells (from Fig. 4a of⁴³). (c) cAMP production in hepatic membranes stimulated by 2 μM glucagon (data from Fig. 1 of⁴⁶, basal response in the absence of glucagon subtracted). Note the membrane preparation used lacks cAMP phosphodiesterase activity⁴⁷. Data were fit to the straight line equation (Eq. 1) using Prism 8⁵⁰. The Slope value on the panels, which is equal to the initial rate and k_τ, is the fitted value ± the fit SEM^51,52.