Figure 3.

TOT-bound estrogen receptor induces recruitment of the CBP coactivator complex to the N-terminal AF-1 domain. (A) The indicated antisera against CBP, p/CIP, or SRC-1/NCOA-1, or an expression vector for N-CoR, was microinjected as indicated into HepG2 cells with a reporter containing two estrogen response elements in front of the p36 minimal promoter. Inset shows Western analysis of expression levels of N-CoR and SMRT in HepG2 and MCF-7 whole-cell extract balanced for total protein loading. (B) Plasmids expressing mutant estrogen receptors were microinjected into Rat-1 cells with α-N-CoR IgG and a reporter containing a minimal promoter (2xEREp36LacZ). (C) A plasmid expressing GAL4/estrogen receptor (amino acids 1–182) was microinjected into Rat-1 cells and tested for dependence on the indicated SRC-1/NCOA-1 family members for constitutive activity. (D) Interaction of ³⁵S-radiolabeled proteins with GST-ER (amino acids 1–182) is shown in comparison to GST-only control lanes.