Transient Calcium and Dopamine Increase PKA Activity and DARPP-32 Phosphorylation
Figure 3
Simulations of Prolonged D1 Receptor Stimulation Paired with Calcium Elevation
(A) Dopamine-dependent increase in phosphoThr34 starting at time 300 s is reduced when, in addition, calcium is elevated at time 1500 s (solid line).
(B) Dopamine-dependent decrease in phosphoThr75 is minimally changed by a subsequent calcium elevation. Reduction of PP2B activity increases the levels of phosphoThr34 and abolishes the calcium-dependent decrease in phosphoThr34 (A, purple dashed line). Furthermore, inhibition of PP2B activity indirectly decreases the levels of phosphoThr75 (B, purple dashed line) because less DARPP-32 is available for phosphorylation on Thr75 since more of it is phosphorylated on Thr34.
(C) Time course of dopamine and calcium elevation.