EXPRESSION OF MURINE LEUKEMIA-VIRUS DNA-POLYMERASE IN MOUSE UTERUS DURING PREGNANCY

The expression of 2 murine leukemia virus proteins, p30 and reverse transcriptase, was studied in subcellular fractions prepared from gravid uteri of NIH Swiss mice at time points throughout gestation. Both proteins were most concentrated the first day after mating, decreased by 90% or more near midgestation and increased dramatically by the first day after parturition. Whereas reverse transcriptase was primarily found in the microsomal fraction, p30 was distributed throughout the subcellular fractions. Expression of these proteins may be mediated by estrogen.