FIGURE 5.
Time course of internalization of the Lys187 mutant CCK receptor constructs in CHO cells. CHO cells stably expressing the wild type (WT), K187A, and K187D CCK receptor constructs were preincubated for 1 h at 4 °C with 50 nM Alexa-CCK, and were subsequently washed and warmed to 37 °C for 0, 2, 5, 10 and 30 min before being fixed. Images are representative of three independent experiments. Mutation of CCK receptor residue Lys187 to either a neutral charge (Ala) or a reversed-charge (Asp) residue had no significant effects on the extent or time-course of CCK receptor internalization.