THE ASSOCIATION OF [6,7-3H]OESTRADIOL WITH A NUCLEAR PROTEIN

Abstract

SUMMARY: The binding of [6,7-³H]oestradiol to nuclei from rat dimethylbenzanthracene-induced (DMBA) mammary tumour, uterine epithelium, anterior pituitary and kidney has been studied. Digestion of nuclei labelled in vivo with [6,7-³H]oestradiol, with RNase, DNase and trypsin indicated that only the last enzyme released tritium from the nucleus, indicating that the receptor is a protein. The optimal concentration of sodium chloride for extracting the oestradiol-receptor complex from tumour nuclei was 1-molar. This concentration was required even after enzymic removal of most of the DNA and RNA. Sodium deoxycholate also extracted oestradiol from nuclei but at the same time dissociated the oestradiol-receptor complex. An attempt was made to fractionate the oestradiol-receptor complex on Sephadex and Biogel columns.