Replicating premeiotic germ cells of the mouse contain a novel DNA primase stimulatory factor.

A protein factor that stimulates DNA primase activity associated with DNA polymerase alpha has been identified in mouse germ cell populations enriched in spermatogonia and preleptotene spermatocytes. The partially purified factor enhances DNA primase activity from homologous cell types as well as DNA primase activity from Xenopus laevis oocytes in a poly dT or M 13 directed reaction. The factor does not stimulate DNA polymerase alpha activity in a gapped salmon sperm or poly dT-rA directed reaction. The DNA primase stimulating factor is identified in a male mouse germ cell population enriched in premeiotic cells; it is not detectable in middle-late pachytene spermatocytes, spermatids, Sertoli cells or fibroblasts.