Figure 1.
Phosphorylation of Chk2 by ATM. (A) Chk2 phosphorylation by ATM from normal lymphoid cells. Immunoprecipitates with anti-ATM antibodies from normal lymphoblastoid cell lines (L40 and C3ABR) or AT lymphoblastoid cell lines (AT59 and L6) were incubated with [γ-32P]ATP and KD Chk2 fused to GST (GST-Chk2-KD) or p53-N47 (29). The control reaction was carried out without immunoprecipitate (No kinase). Proteins were resolved by SDS-PAGE and visualized by autoradiography. (B) Chk2 phosphorylation by transfected ATM. Immunoprecipitates with anti-FLAG from 293T cells transfected with the vector expressing FLAG-tagged wild-type ATM (ATM-WT) or kinase dead ATM (ATM-KD) were incubated with GST-Chk2-KD and [γ-32P]ATP. Proteins were resolved by SDS-PAGE and visualized by autoradiography or Western blotting with anti-FLAG antibodies.