FIGURE 5.

Activation of β₂AR induces dynamic interaction between the receptor and PDE4D isoforms in myocytes. β₁AR-KO expressing FLAG-β₂AR and PDE4D-GFP fusion proteins (4D5, 4D8, and 4D9) are treated with 10 μm isoproterenol (Iso) at the indicated time. The immunoprecipitated (IP) FLAG-β₂AR and the bound PDE4D proteins are blotted with the indicated antibodies. The Western blots are quantified and plotted against the base-line levels of individual isoforms (n = 3). *, p < 0.05; **, p < 0.005; and ***, p < 0.001 when compared with the respective base-line control by Student's t test. In each gel, the total immunoprecipitates are loaded, and the lysate loading represents 5% of the total. IB, immunoblot.