title: The general validity of the subunit model of the progesterone receptor from chick oviduct appears questionable. Comparison of progesterone and estrogen receptor.
abstract: Estrogen and progesterone receptors from chick oviduct were compared with respect to their chromatographic behaviour on DEAE-cellulose and their DNA-binding ability to test the general validity of the subunit model from O'Malley and coworkers. Both hormone-receptor complexes can be separated on DEAE-cellulose into 2 components A and B. The 2 progesterone-receptor components appear to occur in equimolar amounts, whereas in the case of the estrogen receptor the amount of component A is always significantly larger. After trypsin treatment the estrogen component B disappears. The remaining A is a receptor fragment with reduced molecular weight. This and other data indicate that the estrogen component B represents an aggregated form of the estrogen receptor and not a receptor subunit. The trypsinated progesterone-receptor fragments, however, are still separable into 2 components, even though also reduced in molecular weight. Our DNA-binding data of the progesterone-receptor components are almost consistent with earlier data from O'Malley and coworkers, even though we find some DNA-binding ability also for component B. Both estrogen-receptor components exhibit affinity for DNA and significantly more than 50% (up to 80%) of the total estrogen-receptor complex are able to bind to DNA. Furthermore we could show that the estrogen-receptor from chick oviduct can be transformed from a DNA-non-binding to a DNA-binding form, similar to other steroid-hormone receptors. This is not compatible with pre-existing receptor subunits in equimolar amounts, one with and the other without affinity for DNA.
mesh_terms: D000818:Animals; D002645:Chickens; D002845:Chromatography; D002848:Chromatography, DEAE-Cellulose; D003600:Cytosol / Q000032:analysis; D004247:DNA; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D010057:Oviducts / Q000187:drug effects*; D011374:Progesterone / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D011374:Progesterone; D004958:Estradiol; D004247:DNA