FIGURE 5.

RIM1 interacts with Ca_Vβ subunits in HEK-293 cells. Proteins from HEK-293 cells co-transfected with Ca_V1.2α₁/Ca_Vα₂δ-1 together with the Ca_Vβ₂ or Ca_Vβ₃ subunits were immunoprecipitated with anti-Ca_Vβ₂ (A), anti-Ca_Vβ₃ (B), or control (IgG₀) antibodies and subjected to Western blot analysis with anti-RIM antibody. The ∼180-kDa RIM1 band is visualized in the immunoprecipitation (IP) lane. Likewise, proteins from HEK-293 cells co-transfected with Ca_V1.3α₁/Ca_Vα₂δ-1 together with the Ca_Vβ₂ or Ca_Vβ₃ subunits were immunoprecipitated with the anti-Ca_Vβ₂ (C), anti-Ca_Vβ₃ (D), or control antibodies and applied to Western blots. Staining the immunoprecipitates with the RIM1 antibody identified the ∼180 kDa RIM1 band. In all cases, control experiments with the irrelevant antibody as a substitute for the anti-Ca_Vβ antibodies failed to co-immunoprecipitate RIM1. The examples shown are representative of three separate experiments. In all cases, data were collected from the same experiment, and the images are shown separately because they were acquired with different time exposures.