Inability of the estrogen-induced uterine protein to serve as a substrate for the endogenous phosphokinase(s).

We have studied the phosphorylation of soluble proteins from uterine extracts by an endogenous protein kinase. The analysis of phosphorylation patterns by polyacrylamide gel electrophoresis did not reveal any significant difference in this respect between the soluble proteins from control or 17-beta-estradiol stimulated uteri. In both cases, three main components with mol.

Estrogen action: induction of the synthesis of a specific protein (IP) in the myometrium, the stroma and the luminal epithelium of the rat uterus.

The effect of estrogen on the synthesis of a specific uterine protein (estrogen-induced protein=IP) was investigated at the level of the epithelial, stromal and myometrial tissue fractions. For measuring IP induction, the procedure of Katzenellenbogen and Gorski was followed exactly (involving co-electrophoresis of soluble protein extracts from 3H-labeled estrogen treated uteri and 14C-labeled controls) except for the fact that the uteri were fractionated into their three main tissue components before homogenization. The results show that induction of IP synthesis by estradiol takes place in the three tissue fractions considered.

Oestradiol-induced synthesis of a specific uterine protein in propranolol-treated rats.

While there is conflicting evidence concerning an effect of oestradiol on uterine cyclic AMP concentration, results from different laboratories (including ours) are in agreement that even when observed, the early increase in uterine cyclic AMP after oestradiol injection fails to occur when propranolol, a beta-adrenergic blocking agent, is given (50 mug, i.p.) 20 min before the oestradiol.