Schematic representation of nuclear transcriptional corepressors NCoR and SMRT. Model for NCoR/SMRT-mediated transcriptional repression by nuclear receptors. NCoR and SMRTα isoform can interact with GPS2/TBL1/TBLR1 via the repressor domain 1 (RD1). The shorter isoform, SMRTβ, harbors a natural deletion of amino acids 36 to 254. Based on sequence similarity to NCoR, this deletion removes most RD1, including the GPS2/TBL1/TBLR1-binding regions. IDN and IDC represent the receptor interacting domains N- and C-terminal, respectively. RD indicates repressor domain; ID, nuclear receptor interacting domain; NR, nuclear receptor; HDAC, histone deacetylase; GPS2, G protein pathway suppression 2; TBL1, transducin β–like protein 1; TBLR1, TBL1-related protein 1; and CGID, GPS2-interacting domain of TBL1/TBLR1.