Immunoprecipitation and elution of TAPP2. Protein extracts from BJAB B-lymphoma cells or BJAB cells expressing myc-tagged TAPP2 were immunoprecipitated and blotted as indicated. (A) Rabbit anti-TAPP2 can immunoprecipitate (IP) and blot endogenous TAPP2 or myc-tagged TAPP2. IP antibodies are indicated above each lane and blotting antibodies are indicated on the right of each blot. Note the first 2 lanes are whole-cell lysates from the indicated cell line (106 cells per lane), whereas IP lanes represent proteins precipitated from 10 × 106 cells per lane. (B) Elution of TAPP2 using epitope peptide competition. (Left) BJAB extracts were subjected to immunoprecipitation with anti-TAPP2 Ab followed by incubation with various concentration of TAPP2 epitope peptide to elute endogenous TAPP2 from the Ab. (Right) Extracts from BJAB cells expressing myc-tagged TAPP2 were subjected to immunoprecipitation with anti-myc Ab followed by incubation with various concentration of c-myc peptide to elute myc-TAPP2 from the anti-myc Ab. After elution, IP beads were boiled in Laemmli buffer to remove remaining proteins. Eluates and their corresponding bead-bound fractions were blotted with biotinylated anti-TAPP2.
