Figure 1.

(A) Topographical model of α1B-AR. The figure highlights the amino acids N63, D91, N344, and Y348 forming the polar pocket (circles), the DRY sequence, and A293 (squares). (B) Constitutive activation of α_1B-AR by all aa substitutions at position 142. Basal levels of IP accumulation were measured in COS-7 cells expressing the wild-type α_1B-AR (WT) or mutant receptors carrying different amino acids at position 142. The basal IP response was calculated as indicated in the legend of Table 1. The results are from several independent experiments, each performed in triplicate.