Claspin is a protein which plays a major role in DNA replication. It involves in protecting DNA replication forks against DNA damage. In DNA damage response, claspin directly interacts with Rad17, which is required for ATR activation. ATR is activated by various DNA damage and DNA replication stress. Once activated, ATR (ataxia telangiectasia mutated-Rad3 related protein) phosphorylates effector kinase Chk1 which further depends on mediator protein claspin. Claspin helps to stimulate phosphorylation reaction of Chk1.
