Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus: II. isolation and characterization of three small nuclear ribonucleoprotein proteins which bind to nER‐II

Abstract

Three proteins of a goat uterine small nuclear ribonucleoprotein (snRNP) fraction, which bind to nuclear estrogen receptor-II (nER-II) have been isolated and purified. These are the p32, p55, and p60 of which p32 is the major nER-II binding protein. Indirect evidence reveals that p32 binds to the nuclear export signal (NES) on the nER-II. nER-II is a snRNA binding protein while p32 does not bind to the RNA. nER-II along with p32 and p55 form an effective Mg(++)ATPase complex, the activation of which appears to be the immediate reason behind the RNP exit from the nuclei following estradiol exposure. The three nER-II binding proteins bind to the nuclear pore complex; nER-II does not possess this property.

Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus I. Localization of nER‐II in snRNP

“…The data presented in this and the companion paper [Sebastian and Thampan, 2001] is a natural extension of the experimental data reported earlier [Thampan, 1985, 1988, 1989]. A clear lead has been obtained with reference to the biological functions of nER‐II in view of the localization of nER‐II in small nuclear ribonucleoproteins (snRNPs).…”

“…Earlier studies had reported on the activation of a nuclear Mg 2+ ‐dependent ATPase prior to the RNP exit from the nuclei following exposure to estradiol. The nature of the protein complex involved in this ATPase activity has also been recognized in the companion paper [Sebastian and Thampan, 2001].…”

“…Possibly, hormone binding to the nER‐II might bring the nER‐II close to interacting with such a protein, eventually activating the transport process. Data presented in the companion paper [Sebastian and Thampan, 2001] provides evidence for the involvement of NES on nER‐II in the estradiol mediated RNP transport. Three proteins of the snRNP, which recognize the NES in nER‐II, have been identified of which two of them, along with nER‐II bind to the snRNA.…”