Characterization of the AP-2 complex in Ap2β1 mutant mice. Embryonic fibroblasts (A) or brain and liver tissues (B) were collected from wild-type (+/+), heterozygous (Tg/+), and homozygous mutant (Tg/Tg) mice. After lysis, equal protein loadings of homogenates were analyzed by SDS–PAGE and immunoblotting with the indicated antibodies. (C) Lysates from (+/+), (Tg/+), and (Tg/Tg) mouse embryonic fibroblasts were immunoprecipitated with mouse monoclonal anti-α as described in Materials and Methods. Immunoprecipitates were resolved by SDS-PAGE and immunoblotting with antibodies against α (upper panel) or β1+β2 (lower panel).