ATR- interacting protein (ATRIP) is an essential component of the DNA damage checkpoint pathway. ATRIP, phosphorylated by ataxia telangiectasia mutated and Rad3 kinase (ATR), regulates ATR expression, signifying their mutual dependence. The ATR-ATRIP protein kinase complex is essential for the cellular response to replication stress and DNA damage.
It has been shown, in vitro, that replication protein A (RPA) stimulates the binding of ATRIP to single-stranded DNA. This enables the ATR-ATRIP complex to associate with DNA and stimulates phosphorylation of the RAD17 protein that is bound to DNA. ATR/ATRIP exist as a large molecular weight complex that can bind single-stranded DNA cellulose in vitro. Neither ATR nor ATRIP are able to bind DNA individually, nor do they bind DNA in a cooperative manner.