Component of the replication protein A complex (RPA) required for DNA recombination, repair and replication. The activity of RPA is mediated by single-stranded DNA binding and protein interactions (By similarity). Probably involved in repair of double-strand DNA breaks (DSBs) induced by genotoxic stresses (By similarity). Heterotrimer of RPA1, RPA2 and RPA3 (canonical replication protein A complex). No visible phenotype under normal growth conditions, but mutant plants have increased sensitivity to genotoxic stresses and agents that damage DNA bases (UV and methyl methanesulfonate, MMS). Belongs to the replication factor A protein 1 family.