||RAD17 checkpoint clamp loader component encoded by RAD17 is highly similar to the gene product of Schizosaccharomyces pombe rad17, a cell cycle checkpoint gene required for cell cycle arrest and DNA damage repair in response to DNA damage. RAD17 checkpoint clamp loader component shares strong similarity with DNA replication factor C (RFC， and can form a complex with RFCs. RAD17 checkpoint clamp loader component binds to chromatin prior to DNA damage and is phosphorylated by the checkpoint kinase ATR following damage. RAD17 checkpoint clamp loader component recruits the RAD1-RAD9-HUS1 checkpoint protein complex onto chromatin after DNA damage, which may be required for its phosphorylation. The phosphorylation of RAD17 checkpoint clamp loader component is required for the DNA-damage-induced cell cycle G2 arrest, and is thought to be a critical early event during checkpoint signaling in DNA-damaged cells. Multiple alternatively spliced transcript variants of RAD17, which encode four distinct protein isoforms, have been reported. Two pseudogenes, located on chromosomes 7 and 13, have been identified.