HUMAN TAF(II)30 IS PRESENT IN A DISTINCT TFIID COMPLEX AND IS REQUIRED FOR TRANSCRIPTIONAL ACTIVATION BY THE ESTROGEN-RECEPTOR

We showed previously that coactivators mediating stimulation by differ ent activators were associated with the TATA-binding protein (TBP) in distinct TFIID complexes. We have characterized a human TBP-associated factor (TAF), hTAF(II)30, associated with a subset of TFIID complexes . hTAF(II)30 interacts with the AF-2-containing region E of the human estrogen receptor (ER), but not with ER AF-1 or VP16. An antibody agai nst hTAF(II)30 inhibited transcriptional stimulation by the ER AF-2 wi thout affecting basal or VP16-activated transcription and allowed the separation of TFIID complex(es) containing hTAF(II)30 from complexes m ediating the activity of VP16. These results directly demonstrate the existence of functionally dis tinct TFIID populations that share commo n TAF(II)s but differ in specific TAF(II)s.