Coregulators in Nuclear Estrogen Receptor Action

Table 2.

Corepressors in ER Physiology and Pharmacology

Compressor	Full Name	Function/Activity	Repression of ER	Interaction with ER
NCoR	Nuclear receptor corepressor	HDAC (Histone deacetylase)	Pharmacological	Binds ERs AF-2 through CoRNR box motifs
SMRT	Silencing mediator for retinoid and thyroid receptors	HDAC	Pharmacological	Binds ERs AF-2 through CoRNR box motifs
RIP140 (NRIP)	Receptor interacting protein of 140 kDa	Competes for AF-2 coactivator binding; associates with HDACs	Physiological and Pharmacological	Binds ERs AF-2 through LXXLL motifs
REA	Repressor of estrogen receptor activity	Interferes with SRC-1 access to the ERs	Physiological	Indirect
RTA	Repressor of tamoxifen transcriptional activity	Interferes with SRC-1 access to the ERs RNA binding; represses tamoxifen agonist activity through ERα	Pharmacological	Binds ER AF-1
mSiah2	Mammalian homolog of Drosophila Seven in absentia (sina)	Mediates cell-specific repression of NRs by targeting NCoR for proteasomal degradation	Pharmacological	Associates with ER indirectly through binding NCoR