title: An analysis of the binding of the chick oviduct progesterone-receptor to chromatin.
abstract: The binding of progesterone-receptor complexes to chromatin from target and nontarget tissues was studied in vitro. Chromatin from both target and nontarget tissues responds in a similar manner to saly and cofactors and has the same K(D) (approx. 3.10(-9) M) for the progesterone-receptor complex. The only observed difference in the binding of the progesterone-receptor complex to target and nontarget chromatins is the difference in total number of acceptor sites. oviduct chromatin has approx. 1300 sites/pg DNA, spleen chromatin has approx. 840 sites/pg DNA, and erythrocyte chromatin has about 330 sites/pg DNA. The K(D) and number of acceptor sites for progesterone-receptor complex binding to oviduct chromatin remains the same even after extensive purification of the progesterone-receptor complex. Activation of cytosol labeled with [3H]progesterone by preincubation at 25 degrees C, analogous to that required for maximal nuclear binding, occurs if the binding studies to chromatin are performed in 0.025 M salt. The absence of an observable temperature effect when the studies are performed at 0.15 M salt is due to the activation of the receptor by salt. The dissociation of the progesterone-receptor complex from chromatin exhibits a single dissociation rate and the initial event is the appearance of free progesterone rather than a progesterone-receptor complex. Lastly, the treatment of chromatin with an antibody prepared against either single-stranded DNA or double-stranded DNA does not alter the extent of binding of the progesterone-receptor complex. Similarly, pretreatment of chromatin with a single-stranded nuclease does not inhibit the capacity of chromatin to bind the hormone-receptor complex.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002645:Chickens; D002843:Chromatin / Q000378:metabolism*; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D009928:Organ Specificity; D010057:Oviducts / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects; D013154:Spleen / Q000378:metabolism; D013696:Temperature
chemical_list: D002843:Chromatin; D011506:Proteins; D011956:Receptors, Cell Surface; D011374:Progesterone; D004492:Edetic Acid