Figure 3.

Coimmunoprecipitation of CaBP1 and α₁1.2 from transfected cells and rat brain. A, Cells transfected with Ca_v1.2 (α₁1.2-FLAG, β_2A, and α₂δ), Ca_v1.2 plus CaBP1, or CaBP1 alone were subject to lysis and immunoprecipitation using anti-FLAG antibodies. Experiments were done in the presence of 2 mm Ca²⁺ or 10 mm EGTA. Immunoprecipitated proteins were detected by Western blotting with antibodies recognizing the FLAG epitope (top) or CaBP1 (bottom). B, Immunopurification of a complex containing both α₁1.2 and CaBP1 from PSD fractions of rat brain. PSD proteins were isolated on sucrose gradients, solubilized, and incubated with α₁1.2 antibodies. Immunoprecipitated proteins were detected by Western blotting with antibodies against α₁1.2 (top) or CaBP1 (bottom). Immunoblotting of the PSD fraction was also performed with antibodies against PSD-95 (right).