DNA replication in vertebrates requires a homolog of the Cdc7 protein kinase

CDC7 is an essential gene required for DNA replication in Saccharomyces cer evisiae. Cdc7p homologs have recently been identified in vertebrates, but t heir role in DNA replication has not yet been addressed. Here ne show that antibodies to the Xenopus lacvis homolog, xCdc7, interfere with DNA replica tion in vivo in developing embryos and in vitro in cycling egg extracts, We also demonstrate cell cycle-dependent association of sCdc7 with the Mcm co mplex, which binds to replication origins and also is required for DNA synt hesis. Taken together, these data indicate that the function of sCdc7 is co nserved from fungi to vertebrates, sCdc7 protein accumulates after stimulat ion of resting oocytes with progesterone, suggesting a molecular explanatio n for previous observations that the development of the capacity for DNA re plication requires protein synthesis late in meiosis I.