Reduced sulfhydryl groups are required for activation of uterine progesterone receptor. Possible involvement of an inhibitor of activation.

摘要: The dependence of uterine progesterone receptor activation on sulfhydryl groups was studied using binding to DNA-cellulose as a measure activated receptor. Dithiothreitol, thioglycerol, or other reducing reagents stimulated 2- 3-fold. This effect produced under mild conditions, i.e. after 22-h incubation at 0-3 degrees C with 50 mM dithiothreitol. Other characteristics the sulfhydryl-dependent stimulation activation, such pH-dependence and sensitivity blocking agent iodoacetamide, suggest that essential for are different from those involved in steroid binding. Progesterone by reduction reversible process, dependent addition removal (by dialysis) agent. Optimal (up 75% total receptor) occurred when cytosol diluted buffer presence dithiothreitol, suggesting dissociation either subunit an inhibitory factor present may also be process. putative inhibitor appears have Mr greater than equal 30,000 since it is not removed dialysis gel filtration. These results emphasize importance disulfide bridge, perhaps associated DNA-binding domain receptor, key regulatory step mechanism hormone action: subsequent steroid-receptor complex DNA chromatin.