mRNA for the rat uterine estrogen-induced protein. Translation in vitro and regulation by estrogen.

Poly(A)-rich RNA was isolated from uterus and brain of immature rats and translated in the rabbit reticulocyte lysate cell-free protein-synthesizing system. The translation products were analyzed by 1) specific immunoprecipitation using antibodies directed against purified estrogen-induced protein (IP), 2) two-dimensional gel electrophoresis, and 3) partial protease digestion of selected spots from two-dimensional gels. These analyses showed that IP mRNA from both uterus and brain is faithfully translated in the cell-free system. Comparison of translation products derived from uterine mRNA of untreated and 1-h estrogen-treated rats revealed a specific increase in the ability of mRNA from treated animals to direct the synthesis of IP. Thus, estrogen stimulation of IP synthesis results, at least partly, from increased uterine concentrations of IP mRNA.