Repression in absence of ligand 21.5 Steroid receptors have Corepressor severalindependent domains SMRT Figure 21.9 TR and RAR bind the smrt corepressor toroid receptor in the absence of ligand The promoter is not Ligand triggers activation expressed. When SMRT is displaced by binding of Coactivators VOCAL Basal apparatus ligand, the receptor binds a coactivator complex. This CBP/ p300 TBP leads to activation of transcription by the basa RNA polymerase apparatus udano 请莘大Figure 21.9 TR and RAR bind the SMRT corepressor in the absence of ligand. The promoter is not expressed. When SMRT is displaced by binding of ligand, the receptor binds a coactivator complex. This leads to activation of transcription by the basal apparatus. 21.5 Steroid receptors have several independent domains