title: Transformation of calf uterine progesterone receptor: analysis of the process when receptor is bound to progesterone and RU38486.
abstract: Effects of different transforming agents were examined on the sedimentation characteristics of calf uterine progesterone receptor (PR) bound to the synthetic progestin [3H]R5020 or the known progesterone antagonist [3H]RU38486 (RU486). [3H]R5020-receptor complexes [progesterone-receptor complexes (PRc)] sedimented as fast migrating 8S moieties in 8-30% linear glycerol gradients containing 0.15 M KCl and 20 mM Na2MoO4. Incubation of cytosol containing [3H]PRc at 23 degrees C for 10-60 min, or at 0 degrees C with 0.15-0.3 M KCl or 1-10 mM ATP, caused a gradual transformation of PRc to a slow sedimenting 4S form. This 8S to 4S transformation was molybdate sensitive. In contrast, the [3H]RU486-receptor complex exhibited only the 8S form. Treatment with all three activation agents caused a decrease in the 8S form but no concomitant transformation of the [3H]RU486-receptor complex into the 4S form. PR in the calf uterine cytosol incubated at 23 or at 0 degrees C with 0.3 M KCl or 10 mM ATP could be subsequently complexed with [3H]R5020 to yield the 4S form of PR. However, the cytosol PR transformed in the absence of any added ligand failed to bind [3H]RU486. Heat treatment of both [3H]R5020- and [3H]RU486-receptor complexes caused an increase in DNA-cellulose binding, although the extent of this binding was lower when RU486 was bound to receptors. An aqueous two-phase partitioning analysis revealed a significant change in the surface properties of PR following both binding to ligand and subsequent transformation. The partition coefficient (Kobsd) of the heat-transformed [3H]R5020-receptor complex increased about 5-fold over that observed with PR at 0 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Biological Sciences, Oakland University, Rochester, Michigan 48063.
authors: V K
authors: VK
authors: Moudgil
authors: C
authors: C
authors: Hurd
mesh_terms: D000818:Animals; D002417:Cattle; D003600:Cytosol / Q000378:metabolism; D004963:Estrenes / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D015735:Mifepristone; D011374:Progesterone / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000302:isolation & purification / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
chemical_list: D004963:Estrenes; D011980:Receptors, Progesterone; D015735:Mifepristone; D011374:Progesterone