FIGURE 6.

Expression and activity of hA₁R point mutants. A–C, confocal images of HEK293 cells expressing wild-type hA₁R (A), hA₁R-H251A (B), or hA₁R-H278A (C) and immunostained with anti-A₁R antibodies. Untransfected HEK293 cells in the same field of view were not immunostained, confirming antibody specificity. Scale bar = 10 μm. D, calcium mobilization in HEK293 cells co-expressing the indicated hA₁R mutant and Gqi and then stimulated with increasing concentrations of the indicated compounds. For all conditions, cells were incubated with 10 μm αβ-met-ADP for 3 min and then stimulated with agonist in the presence of 10 μm αβ-met-ADP. AUC measurements extended for 1 min from agonist addition. All experiments were performed in duplicate, except H278A-AMP, which was performed in triplicate. n = 17–49 cells per condition. All data are presented as means ± S.E.