title: Evidence for two structurally related progesterone receptors in chick oviduct cytosol.
abstract: The existence of two progesterone receptor forms present in crude cytosol of chick oviduct has been demonstrated by photoaffinity labelling using [3H]R5020. On SDS-polyacrylamide gels these two forms exhibit app. Mr-values of 79000 and 109000 corresponding to the progesterone receptor forms A and B. Peptide maps of photoaffinity-labelled steroid receptors have been established by limited proteolysis with alpha-chymotrypsin. The peptide map obtained for chick oviduct cytosol progesterone receptor crosslinked with [3H]R5020 proved to be the sum of peptides obtained from partially purified preparations of forms A and B. The peptide maps of both progesterone receptor forms were identical for peptides below the Mr-value of form A, indicating extensive homology of the two forms. A significantly different peptide pattern was observed for the rat liver glucocorticoid receptor crosslinked with [3H]triamcinolone acetonide. Prolonged proteolysis with chymotrypsin gave rise to peptides with Mr-values of 6000 and 10000 from the hormone-binding domain of progesterone and glucocorticoid receptors, respectively.
mesh_terms: D000818:Animals; D002645:Chickens; D003600:Cytosol / Q000378:metabolism; D005260:Female; D008099:Liver / Q000378:metabolism; D010057:Oviducts / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000302:isolation & purification; D011980:Receptors, Progesterone / Q000302:isolation & purification*
chemical_list: D010446:Peptide Fragments; D011965:Receptors, Glucocorticoid; D011980:Receptors, Progesterone