Editing Equol (section)

===Estrogen receptor binding===
(''S'')-equol is a [[nonsteroidal]], selective [[agonist]] of [[ERβ]] (K<sub>i</sub> = 16 nM) with 13-fold selectivity for ERβ over [[ERα]].<ref name="MuthyalaJu2004" /> Relative to (''S'')-equol, (''R'')-equol is less potent and binds to ERα (K<sub>i</sub> = 50 nM) with 3.5-fold selectivity over ERβ.<ref name="MuthyalaJu2004" /> (''S'')-Equol has about 2% of [[estradiol]]'s binding affinity for human [[estrogen receptor alpha]] (ERα) and 20% of estradiol's binding affinity for human [[estrogen receptor beta]] (ERβ). The preferential binding of (''S'')-equol to ERβ vs. ERα and in comparison to that of estradiol suggests the molecule may share some of the characteristics of a [[selective estrogen receptor modulator]] (SERM).<ref>{{cite journal|last=Setchell|first=KD |author2=Clerici, C |author3=Lephart, ED |author4=Cole, SJ |author5=Heenan, C |author6=Castellani, D |author7=Wolfe, BE |author8=Nechemias-Zimmer, L |author9=Brown, NM |author10=Lund, TD |author11=Handa, RJ |author12=Heubi, JE|title=S-equol, a potent ligand for estrogen receptor beta, is the exclusive enantiomeric form of the soy isoflavone metabolite produced by human intestinal bacterial flora |journal=[[The American Journal of Clinical Nutrition]]|date=May 2005|volume=81|issue=5|pages=1072–9|pmid=15883431|doi=10.1093/ajcn/81.5.1072 |doi-access=free }}</ref> Equol has been found to act as an [[agonist]] of the [[GPER]] (GPR30).<ref name="ProssnitzBarton2014">{{cite journal|last1=Prossnitz|first1=Eric R.|last2=Barton|first2=Matthias|title=Estrogen biology: New insights into GPER function and clinical opportunities|journal=Molecular and Cellular Endocrinology|volume=389|issue=1–2|year=2014|pages=71–83|issn=0303-7207|doi=10.1016/j.mce.2014.02.002|pmid=24530924|pmc=4040308}}</ref>