Figure 4.

N-terminal lysine residues are critical for Mdm2-mediated GRK2 degradation. (A) Turnover of wild-type GRK2 and GRK2-K19,20,30,31R mutant proteins was assessed by pulse–chase experiments in HEK-293 cells as described in Materials and methods and Figure 2. (B) Similar experiments were performed in cells cotransfected with an Mdm2 construct. In both panels, data are mean±s.e.m. from three to four independent experiments (^**P<0.01), and representative fluorographies are shown.