Differential ATRA sensitivities of N-CoR association with RARα and its PML and PLZF fusions. (A) Schematic representation of PML, PLZF, RARα1, PML-RARα, PLZF-RARα, and N-CoR. RI, RII, and RIII, N-CoR repression domains. RIDII and RIDI, N-CoR interaction domains with RARα. CoR-box, corepressor interaction domain in the RARα. Solid boxes represent the Sin3 interaction domains of N-CoR. Numbers correspond to the amino acids flanking various functional domains, indicated with different patterns, within a given protein. Fusion points between RARα and PLZF or PML are indicated by arrowheads. (B) Binding of RARα, PML-RARα, and PLZF-RARα to GST-N-CoR corepressor (amino acids 1679-2453). Radiolabeled receptors, synthesized in vitro, were incubated with immobilized GST-N-CoR over a range of ATRA concentrations, as indicated. Bound proteins were analyzed by SDS-PAGE and autoradiography.