Invitrogen™ DBF4 Recombinant Rabbit Monoclonal Antibody (JE52-50)

Activator of S phase kinase (ASK, DBF4) is a novel regulatory subunit of the human Cdc7 kinase complex that plays a pivotal role in G1/S cell cycle transition in mammalian cells. The increase in Cdc7 kinase activity at the G1/S boundary is at least partly accounted for by the elevated expression of ASK in late G1. ASK interacts with replication origins in vivo, suggesting that Cdc7 may trigger S phase by directly activating the replication initiation complexes assembled at the origins. Human ASK protein levels are regulated during the cell cycle with a pattern that matches that of human Cdc7 protein kinase activity. Human Cdc7-ASK kinase is directly involved in regulating the initiation of DNA replication by targeting MCM2 protein in mammalian cells. Nuclear localization and chromatin binding of endogenous huCdc7 and GFP-ASK is presumably imported into nuclei through its two nuclear localization signals at telophase, it may require additional signals for chromatin binding, the level of which increases at late G1 ohase. A functional link may exist between menin, a tumor suppressor protein mutated in multiple endocrine neoplasia type I (MEN1), and ASK in the regulation of cell proliferation.