Steady-state activation of G_q under cellular conditions.

Fractional activation Z was simulated at varying total concentrations of receptor and GAP, with 1.6×10⁻⁴ M G_q, for cytosolic concentrations of 200 µM GTP, 20 µM GDP, and 1 mM P_i. Z values for colors on the contour plot are defined in the reference bar below. Protein concentrations are expressed with reference to the membrane volume.