Figure 6: Truncation of the third intracellular loop does affect ERK activation and internalization.

(a) Interaction of phosphorylated ERK2 MAP Kinase with β₂V₂R^ΔICL3+βarr1+ScFv30 complex as assessed by ELISA approach. Similar to β₂V₂R, β₂V₂R^ΔICL3 also forms stable complexes with phosphorylated ERK2. Data represent mean±s.e.m. of three independent experiments each carried out in duplicate and analysed using one-way ANOVA with Bonferroni post-test (***P<0.001). (b) Agonist induced activation of ERK1/2 MAP kinase for β₂V₂R and β₂V₂R^ΔICL3 shows a similar temporal pattern suggesting that truncation of the third intracellular loop, and, therefore, ablation of the core interaction, does not significantly affect ERK activation. The experiment was repeated four times with identical results and a representative image is shown. (c) Quantification of the ERK activation data presented as mean±s.e.m. of four independent experiments. (d) Agonist induced activation of ERK1/2 MAP kinase downstream of β₂AR^WT and β₂AR^ΔICL3 also reveals similar pattern suggesting the dispensability of the core interaction even for class A receptors. A representative image and quantitation of seven independent experiments are shown. (e) Similar to ERK activation, agonist induced internalization of β₂V₂R^ΔICL3 also exhibits a comparable pattern to β₂V₂R^WT albeit with an increased kinetics. (f) β₂AR^ΔICL3 also undergoes robust internalization upon agonist stimulation similar to β₂AR^WT. Data in e and f represent six independent experiments each carried out in duplicate and presented as mean±s.e.m.