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Mol. Cell. Biol., Oct 1997, 6131-6138, Vol 17, No. 10
BC Lin, SH Hong, S Krig, SM Yoh and ML Privalsky
Nuclear hormone receptors are ligand-regulated transcription factors that
modulate gene expression in response to small, hydrophobic hormones, such
as retinoic acid and thyroid hormone. The thyroid hormone and retinoic acid
receptors typically repress transcription in the absence of hormone and
activate it in the presence of hormone. Transcriptional repression is
mediated, in part, through the ability of these receptors to physically
associate with ancillary polypeptides called corepressors. We wished to
understand the mechanism by which corepressors are recruited to unliganded
nuclear hormone receptors and are released on the binding of hormone. We
report here that an alpha- helical domain located at the thyroid hormone
receptor C terminus appears to undergo a hormone-induced conformational
change required for release of corepressor and that amino acid
substitutions that abrogate this conformational change can impair or
prevent corepressor release. In contrast, retinoid X receptors appear
neither to undergo an equivalent conformational alteration in their C
termini nor to release corepressor in response to cognate hormone,
consistent with the distinct transcriptional regulatory properties
displayed by this class of receptors.
Copyright © 1997, American Society for Microbiology
A conformational switch in nuclear hormone receptors is involved in coupling hormone binding to corepressor release
Division of Biological Sciences, University of California at Davis, 95616, USA.
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