Estradiol receptor and cyclic nucleotide phosphodiesterase: functional relationship, possible role of guanine...

The inhibitory effect of estradiol (10(-9)M - 2 X 10(-5)M) on the cyclic nucleotide phosphodiesterase (EC 3.1.4.17) activity of cytosol from rat uterine tissue and human myometrium and endometrium was established. The hormone action was shown to disappear due to preparative separation of the receptor and the enzyme; the effect reappeared after protein mixing. In the presence of GTP, Gpp (NH)p, NaF and cholera toxin the estradiol action on the phosphodiesterase activity was significantly decreased or failed to be revealed. The antibodies raised against G-proteins of retina photoreceptor membranes abolished the hormone action on phosphodiesterase. A conclusion is drawn that in uterine tissue there exists a functional connection between estradiol receptor and phosphodiesterase. The necessary participation of G-proteins in signal transmission is postulated.