Replication protein A 70 kDa DNA-binding subunit is a protein that in humans is encoded by the RPA1 gene. Diseases associated with RPA1 include xeroderma pigmentosum, group a and atrophic rhinitis. Among its related pathways are Cell Cycle, Mitotic and Transport to the Golgi and subsequent modification.

As part of the heterotrimeric replication protein A complex (RPA/RP-A), binds and stabilizes single-stranded DNA intermediates, that form during DNA replication or upon DNA stress. It prevents their reannealing and in parallel, recruits and activates different proteins and complexes involved in DNA metabolism. Thereby, it plays an essential role both in DNA replication and the cellular response to DNA damage. In the cellular respone to DNA damage, the RPA complex controls DNA repair and DNA damage checkpoint activation.