Estrogen receptor

  • OMIM: 601 663
  • UniProt: Q92731

Estrogen receptors (ER) are steroid receptors to the superfamily of nuclear receptors NR3I ( nuclear receptor subfamily 3, group I) and are activated by the steroid hormone estrogen. The main function of the estrogen receptor is a DNA -binding transcription factor that regulates the expression of the target gene. However, the estrogen receptor does not have additional functions independent of DNA binding.

Structure and Bonding

Two human receptor subtypes have been identified, both have the same basic structure:

  • Estrogen receptor α ( ERa, NR3A1 )
  • Estrogen receptor β ( ERβ, NR3A2 )

Both receptors have six domains ( A-F):

  • A / B domain: Contains a ligand-independent transcriptional activation function (AF -1).
  • C domain: DNA - binding domain ( DBD). It contains two zinc finger motifs.
  • D- domain: dimerization.
  • E / F domain: Contains the ligand binding domain (LBD ) and a so-called transactivation region at the C -terminus ( AF -2).

Since both subtypes are expressed in many cells at the same time, it comes in the hormone- activated receptor dimerization in the formation of ERa ( αα ) or ERβ ( ββ ) homodimers or ERαβ ( αβ ) heterodimers.

Different ligands may differ in their affinity in terms of the two receptor isoforms:

  • Estradiol and coumestrol binds to both receptors
  • Estrone and raloxifene bind preferentially to ERa
  • Estriol and genistein bind to ERβ

Selective estrogen receptor modulators preferably bind to either the α - or β - subtype of the receptor.

Protein isoform Human Genome Organisation Digital Object Identifier
317503
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