| Abstract: | Various aspects of the interaction of oestrogen-receptor complexes with calf uterine chromatin covalently coupled to cellulose were analysed. Partially purified 3H]oestradiol-receptor complexes were bound to intact, or partially deproteinized, chromatin resins. Proteins were removed from the chromatin-cellulose resins by extraction with high molarities of salt, including NaCl/urea, guanidine hydrochloride and guanidine thiocyanate. After extensive washing to remove the salt, 3H]oestradiol-receptor-complex solutions were added to the resins and the degree of binding was determined. The extent of 3H]oestradiol-receptor-complex binding to chromatin was enhanced by extraction of chromosomal proteins. By varying the molarity of the salt, and consequently the extent of protein removal, it was possible to resolve 3H]oestradiol-receptor-complex binding to guanidine thiocyanate-extracted chromatin into two components. Similarly, 3H]oestradiol-receptor-complex binding to guanidine hydrochloride-treated chromatin included three regions of enhanced binding capacity. The 3H]oestradiol-receptor-chromatin interaction was saturable with respect to both intact and salt-extracted resins. Thus uterine chromatin may contain three or more specific classes of acceptors for the oestrogen-receptor complex. |
