Figure 2. The β₁AR A187V mutation alters protein stability and cAMP production.

(A) Degradation assay of β₁AR in transfected HEK293 cells. Twenty-four hours after transfection, cells were treated with 100 μg/ml CHX and harvested at indicated time points. Bands inside the two red boxes indicate β₁AR protein of different sizes in the SDS gel. Quantified results are shown on the right. β₁AR protein levels at the starting point (t=0 hours) were normalized to 1.

(B) The β₁AR A187V mutation confers altered downstream signaling output in response to isoproterenol in cultured cells. Heterozygous expression of β₁AR A187V and WT leads to a reduction in cAMP production.

(C and D) Western blotting results of endogenous β₁AR protein from the heart (C) and brain (D) lysates of Adrb1+/+, and Adrb1+/m animals. N=4 mice per group. NS, non-specific band. Quantified results are shown on the right.

(E and F) q-RTPCR results of Adrb1 mRNA normalized to Actin mRNA from the heart (E) and brain (F) tissues of Adrb1+/+ and +/m animals. N=4 mice per group.

* P<0.05, **P<0.01, n.s.= not significant. Two way RM ANOVA, post-hoc Sidak’s multiple comparisons test for (A) and (B). Two-tailed Student’s t-test for (C)-(F). Error bars represent ± SEM.