Fig. 5. Effect of receptor phosphorylation on DAMGO- and morphine-induced OPRM1 desensitization in HEK293 cells.
The ability of 100nM DAMGO and morphine to induce desensitization of wild type OPRM1(■) and phosphorylation deficient OPRM1(363/370/375)(○) was examined in HEK293 cells. Total [Ca2+]i response of the second injection was quantitatively analyzed as described in figure legend of Figure 1B. The agonist-induced desensitization rate was calculated as described in the legend of Fig. 2B. Data were showed as the averages of n≥3 experiments in which HEK293 cells pretreated with 100nM DAMGO (panel A) and 100nM morphine (panel B) respectively to induce OPRM1 desensitization. * denotes p < 0.05; and ** denotes p< 0.01.