FIGURE 5.

GRK2 phosphorylation on Ser³⁷⁵ attenuates PKCϵ activation. A, HEKOPRM1, HEKS363A, HEKT370A, and HEKS375A cells were treated with PBS (Control), 1 μm morphine, 10 nm etorphine, 10 nm fentanyl, and 1 μm DAMGO for 5min. The activity of PKCϵ was determined. B and C, HEKOPRM1 was transfected with a vector, GRK2, and GRK2-K220R. One day after transfection, cells were treated with agonists as in A. Receptor phosphorylation on Ser³⁷⁵ was determined in B. PKCϵ activities were normalized against that in “Control with Vector” in C.