Figure 3.

Segregation of the ERα-enhancing activity of CITED1 from its p300-dependent transactivating activity. (A) Alanine scan mutants of CITED1. Amino acids 155–167 of CITED1, which locate in the N-terminal region of the CR2 domain, were systematically mutated. (B) Protein expression of the CITED1 alanine scan mutants. CITED1 mutants were transfected into COS-1 cells, and their expression was evaluated by anti-HA Western blotting. ΔCR2, a CITED1 deletion mutant lacking the CR2 domain. (C) Requirement of amino acids 157–158 (VL) for the ERα-enhancing activity of CITED1. Cells were cotransfected with pGLUC8, GAL4DBD–ERα–AF2, and the CITED1 mutants, followed by stimulation with 100 nM 17β-estradiol (E2) for 24 h before luciferase assay. (D) The mut2 CITED1 mutant that lost the ERα-enhancing activity retains the p300-dependent transactivating activity. Cells were cotransfected with pGLUC8 and GAL4DBD-fusion CITED1 mutants, followed by luciferase assay.