Thyroid hormone receptor

Thyroid hormone receptor alpha
Identifiers
Symbol	THRA
Alt. symbols	THRA1, THRA2, ERBA1
Entrez	7067
HUGO	11796
OMIM	190120
RefSeq	NM_199334
UniProt	P10827
Other data
Locus	Chr. 17 q11.2-17q12

Thyroid hormone receptor beta
Identifiers
Symbol	THRB
Alt. symbols	ERBA2
Entrez	7068
HUGO	11799
OMIM	190160
RefSeq	NM_000461
UniProt	P10828
Other data
Locus	Chr. 3 p24.1-p22

The thyroid hormone receptor (TR) is a type of nuclear receptor that is activated by binding thyroid hormone.

Among the most important functions of thyroid hormone receptors are regulation of metabolism and heart rate. In addition, they play critical roles in the development of organisms.

Thyroid hormone receptors regulate gene expression by binding to hormone response elements (HREs) in DNA either as monomers, heterodimers with retinoid X receptor (RXR; which in turn is activated by binding to 9-cis-retinoic acid) or as homodimers. However TR/RXR heterodimers are the most transcriptionally active form of TR.

In the absence of hormone, TR in complex with corepressor proteins bind to HREs in a transcriptionally inactive state. Binding of thyroid hormone results in a conformational change in TR which displaces corepressor from the receptor/DNA complex and recruitment of coactivator proteins. The DNA/TR/coactivator complex then recruits RNA polymerase that transcribes downstream DNA into messenger RNA and eventually protein that results in a change in cell function.

There are three forms of the thyroid hormone receptor designated alpha-1, beta-1 and beta-2 that are able to bind thyroid hormone. There are two TR-α receptor splice variants encoded by the THRA gene and two TR-β isoform splice variants encoded by the THRB gene:

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