Cdc7 protein kinase for DNA metabolism comes of age

The Cdc7 protein kinase is the product of an essential cell cycle gene, and is involved in three aspects of DNA metabolism: mitotic DNA replication, meiotic DNA recombination, and replication-dependent DNA repair. The mechanism by which Cdc7 regulates each of its cellular functions is an issue of considerable interest. Recently, much of the research regarding the regulation of cell cycle progression has focused on the regulatory action of cyclins on their catalytic counterparts. We propose that the function of Cdc7 in cell cycle progression is mediated in a similar manner, in that Dbf4, a protein whose transcript level is known to fluctuate in the cell cycle, is essential for Cdc7 kinase activity. The periodic association of Dbf4 with Cdc7 may account for the regulation of Cdc7 kinase function and progression through the cell cycle.