The subunits of the S-phase checkpoint complex Mrc1/Tof1/Csm3: dynamics and interdependence.

Background: The S-phase checkpoint aims to prevent cells from generation of extensive single-stranded DNA that predisposes to genome instability. The S. cerevisiae complex Tof1/Csm3/Mrc1 acts to restrain the replicative MCM helicase when DNA synthesis is prohibited.