RPA1 (Replication protein A1) is the largest component (70kDa) of the heterotrimeric complex RPA with three functional domains. It plays a pivotal role in the DNA replication, repair, and recombination. It also participates in the transcriptional regulation of various genes. Its zinc finger domain binds to the single-stranded DNA to form the RPA holocomplex. In addition, it also helps to unwind the double strand, stimulates DNA polymerases α and δ, and form the initial short Okazaki fragments. at the damage site, RPA1 recruits DNA double-strand break repair factors, RAD51 and RAD52 to the chromatin. RPA1 plays an essential role in the DNA replication and mismatch repair but it is not mandatory for nucleotide excision repair. In the nucleotide excision repair, it recruits DNA damage proteins like XPA and XPG.
