Relative binding of certain steroids of low polarity to human sex hormone-binding globulin: strong binding of 2-methoxyestrone, a steroid lacking the 17 beta-OH group.
The cross-reactivities for binding sites on human sex hormone-binding globulin (SHBG) of a number of steroids of low polarity, including progesterone and estrogen metabolites, were studied. Binding relative to testosterone (100%) was low (less than or equal to 3%) except for 2-methoxyestrone (81%), 3-acetoxyestradiol (16%), 4-methoxyestradiol (6%), 3 beta-hydroxy-5 beta-pregnan-3-one (5.8%), 5 alpha-dihydrodeoxycorticosterone (4.5%), deoxycorticosterone (4%), 20 alpha-hydroxy-5 alpha-pregnan -3-one (4%), 4-methoxyestrone (4%) and 5 alpha-dihydroprogesterone (3.5%). 2-Methoxyestrone is the only steroid lacking a 17 beta-hydroxyl group which binds to SHBG with strong affinity.
D001667:Binding, Competitive; D004970:Estrone / Q000031:analogs & derivatives*; D006801:Humans; D006894:Hydroxyestrones / Q000378:metabolism*; D006900:Hydroxylation; D011374:Progesterone / Q000378:metabolism; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism
D006894:Hydroxyestrones; D012738:Sex Hormone-Binding Globulin; D004970:Estrone; D013739:Testosterone; D011374:Progesterone; C003655:2-methoxyestrone