Enables single-stranded DNA binding activity. Predicted to be involved in several processes, including DNA metabolic process; DNA unwinding involved in DNA replication; and protein localization to chromosome. Predicted to act upstream of or within several processes, including hemopoiesis; homeostasis of number of cells within a tissue; and in utero embryonic development. Part of DNA replication factor A complex. Orthologous to human RPA1 (replication protein A1). [provided by Alliance of Genome Resources, Apr 2022]