SYNTHESIS OF GAP JUNCTION PROTEINS AND COLLAGENASES IN THE PREIMPLANTATION RAT UTERUS

Synthesis of gap junction proteins (GJPs) and of collagenases in the rat uterus has been studied under two physiological conditions: various stages of the estrus cycle, and the early pregnangy period. The synthesis has been studied by incubating uterine horns in a short-term tissue culture medium containing radioactively-labeled amino acids, followed by a double antibody immunoprecipitation of the labeled proteins. After exposure of the media to either anti-collagenase IgG(s) or anti-GJPs IgG(s), the final immunoprecipitation was achieved with the use of goat anti-rabbit IgG. Collagenase (s) synthesis was found to reach the peak, during the estrus cycle, at the proestrus stage, while GJP synthesis reached the maximum during the estrus stage. In the preimplantation, pregnant, rat uterus the syntheses of both the proteins reached the respective peak activities on day 4 of pregnancy about 24 h before the expected time of ovum implantation. A study of the literature reveals that this time coincides with a spurt in exposure of the progesterone dominated uterus to estradiol.