Application
Peptide Competition and Phosphatase Treatment. Lysates prepared from K562 cells left unstimulated (1) or stimulated with PMA (2-6) were resolved by SDS-PAGE on a 10% polyacrylamide gel and transferred to PVDF. Membranes were either left untreated (1-5) or treated with lambda phosphatase (6), blocked with a 3% milk-TBST buffer for one hour at room temperature, and incubated with PKCµ/PKD [pS742] antibody for two hours at room temperature in a 3% milk-TBST buffer, following prior incubation with: no peptide (1, 2, 6), the non-phosphopeptide corresponding to the immunogen (3), a generic phosphoserine-containing peptide (4), or, the phosphopeptide immunogen (5). After washing, membranes were incubated with goat F(ab'e;)2 anti-rabbit IgG HRP conjugate and bands were detected using the Pierce SuperSignal™ method. The data show that only the peptide corresponding to PKCµ/PKD [pS742] blocks the antibody signal. The data also show that phosphatase stripping eliminates the signal, verifying that the antibody is phospho-specific.