Figure 1
From: To bind or not to bind – how to down-regulate target genes by liganded thyroid hormone receptor?
Alternative models for negative gene transcription by thyroid hormone. A) Thyroid hormone receptor (TR) binds together with its dimerization partner RXR to a negative thyroid hormone response element (negative TRE). The un-liganded TR recruits a coactivator complex (CoA) leading to gene activation. If thyroid hormone (TH) binds to TR the liganded TR recruits a corepressor complex (CoR) leading to silencing of gene expression. B) TR does not bind directly to DNA but rather via unknown transcription factors (TF X). The functional readout is as described for model A. C) TR does not bind to DNA at all but sequesters CoR away from DNA-bound transcription factors (TF X) in the absence of TH. In the presence of TH, liganded TR sequesters CoA away from DNA-bound transcription factors. For further explanation, see text.