Synthesis and developmental regulation of an egg specific mouse protein translated from maternal mRNA

Proteins synthesized by DDK mice embryos were analyzed by 2D electrophoresis and a new egg-specific polypeptide, D14, was identified. The protein is characterized by its high rate of synthesis and electrophoretic properties (MW 36,500, pl greater than 8). The synthesis of D14 is strictly developmentally regulated: starting in the maturing oocyte in the few hours following germinal vesicle breakdown (GVBD), it remains high over the first cell cycle and decreases abruptly during the two-cell stage. The arrest of D14 synthesis is triggered by egg activation and does not directly depend on transcription by the zygotic genome. Nevertheless, drugs that perturb the onset of zygotic transcription concomitantly inhibit D14 arrest of synthesis. D14 is present in both cytoplasmic and nuclear compartments at the two-cell stage; it is very stable and remains detectable at least until the eight-cell stage in the preimplantation embryo. Embryos of wild strains of mice synthesized either D14 or a D14 related polypeptide at a rate comparable to that of DDK embryos, which was at least ten times greater than that found in other laboratory strains. Both the developmental regulation and the genetic variability in its rate of synthesis make D14 an interesting polypeptide for the study of regulation of maternal information in the very early stages of mouse embryo development.