As part of the heterotrimeric replication protein A (RPA) complex, binds and stabilizes single-stranded DNA intermediates, that form during DNA replication or upon DNA stress (By similarity). It prevents their reannealing and in parallel, recruits and activates different proteins and complexes involved in DNA metabolism (By similarity). Thereby, it plays an essential role both in DNA replication and the cellular response to DNA damage (By similarity). In the cellular response to DNA damage, the RPA complex controls DNA repair and DNA damage checkpoint activation (By similarity). Component of the replication protein A complex (RPA), a heterotrimeric complex composed of RPA1, RPA2/TEB2 and RPA3/TEB3. Belongs to the replication factor A protein 1 family.