The Silencing mediator of retinoic acid & thyroid hormone receptor protein, commonly called the SMRT protein mediates the transcriptional repression of some nuclear receptors by promoting chromatin condensation, thus preventing access of the basal transcription machinery. Consistent with this activity, this protein is known to form a large corepressor complex containing SIN3A/B and histone deacetylases HDAC1 and HDAC2. SMRT is also a component of the N-Cor repressor (nuclear receptor corepressor), a multi-subunit complex minimally composed of NCOR1, NCOR2, HDAC3, TBL1X, TBL1R, CORO2A and GPS2. SMRT and nuclear receptor corepressor N-CoR are related transcriptional corepressors which contain two distinct domains capable of interacting with unliganded nuclear receptors to repress their basal transcriptional activity.