Stimulation and selective inhibition of protein synthesis by 17 beta-estradiol, in the uterus of immature rats

The in vitro translation of RNAs extracted from immature female rat uteri 24 hrs. after one or four daily injections of 17 beta-oestradiol was carried out. The proteins labelled with (35S) methionine were separated by polyacrylamide gel electrophoresis and the resulting autoradiograms were scanned. The densitometric profile of uterine proteins obtained after a single injection of oestrogen showed a considerable increase in the majority of them, compared with controls. Following four injections of 17 beta-oestradiol the synthesis of all but one of the uterine proteins was observed. The Mr of the protein induced by repeated administration of oestrogens was about 105 kdaltons. This protein could possibly be involved in the inhibition of protein synthesis observed in the rat uterus after reiterated injections of 17 beta-oestradiol to female rats.