Nuclear retention of receptor–oestrogen complex and nuclear acceptor sites

Abstract

Nuclear retention of receptor-estrogen complex and nuclear acceptor sites are discussed. Evidence that a limited number of receptor-estrogen complexes are bound in the nucleus of rat uterine cells and that these sites may be specific nuclear acceptor sites is presented. Salt extraction of uterine nuclei was used to test the hypothesis that long-term retention of the receptor-estrogen complex in the nucleus is due to the binding of these complexes to a limited number of nuclear acceptor sites and that retention at these acceptor sites for more than 4-6 hours is a requirement for true growth. The number of potassium chloride-resistant nuclear sites was identical to the number of sites required for maximal uterine growth therefore it is proposed that these binding sites in the nucleus represent specific acceptor sites.