PML I interacting domain is located at the C-terminal of AML1. (A) Schematic diagram of the structure of AML1 deletion mutants. The Runt, activation, and inhibition domains are indicated as Runt, AD, and ID, respectively. Nuclear import signal (NLS) and nuclear matrix targeting signal (NMTS) are shown. (B) Identification of regions of AML1b required for interaction with PML I. BOSC23 cells were cotransfected with PML I and control vector (mock) or AML1 constructions as indicated. The expression of PML I in the lysates of transfectants was detected by immunoblotting using anti-HA (3F10) antibody (top). The lysates of transfectants were immunoprecipitated with anti-FLAG (M2) antibody. The immunoprecipitates were analyzed by immunoblotting using anti-FLAG (M2) (middle) and anti-HA (3F10) antibodies (bottom). (C) The Runt domain is dispensable for the interaction of AML 1 with PML I. BOSC23 cells were cotransfected with PML I and full-length AML1b or deletion mutants of AML1 partially lacking Runt domain as indicated. The expression of PML I (top) and AML1 (middle) proteins in the cell lysates was detected with anti-HA antibody and anti-FLAG antibody, respectively. The immunoprecipitates with anti-FLAG antibody were analyzed using anti-HA antibody (lower).