FIGURE 4.
KCNQ1-KCNE1 associates with AC9 activity in transgenic mouse heart. A, heart extracts from WT or KCNQ1-KCNE1 transgenic (TG+) mice were immunoprecipitated (IP) with goat IgG (control) or anti-KCNQ1 antibody. Immunoprecipitates were stimulated with Gαs/forskolin, and associated AC activity was measured and normalized to IgG of WT mouse heart (n = 3). B, immunoprecipitates of KCNQ1 (or control IgG) from WT or KCNQ1-KCNE1 transgenic hearts were subjected to Western blot analysis with anti-Yotiao, anti-KCNQ1, anti-AC9, and anti-RIIβ (PKA regulatory subunit) antibodies. C, WT or KCNQ1-KCNE1 transgenic mouse heart extracts (n = 3) were incubated with GST (5 μm) or GST-AC9-NT (5 μm) before immunoprecipitation with anti-KCNQ1 antibody. Immunoprecipitates were stimulated with 400 nm Gαs (p < 0.05). AC9-NT inhibited KCNQ1-associated AC activity. D, WT and KCNQ1-KCNE1 transgenic heart extracts were immunoprecipitated with anti-KCNQ1 antibody. Immunoprecipitates were stimulated with Gαs versus Gαs/Gβγ, and associated AC activity was measured (n = 3). Gβγ did not activate KCNQ1-associated AC. For A, C, and D, data are presented as the mean ± S.E. (n = 3). ***, p < 0.001 using the Bonferroni t test.