Component of the SOSS complex, a multiprotein complex that functions downstream of the MRN complex to promote DNA repair and G2/M checkpoint. The SOSS complex associates with single-stranded DNA at DNA lesions and influences diverse endpoints in the cellular DNA damage response including cell-cycle checkpoint activation, recombinational repair and maintenance of genomic stability. Required for efficient homologous recombination-dependent repair of double-strand breaks (DSBs) and ATM-dependent signaling pathways (By similarity). Component of the SOSS complex, composed of SOSS-B (SOSS-B1/NABP2 or SOSS-B2/NABP1), SOSS-A/INTS3 and SOSS-C/INIP. SOSS complexes containing SOSS-B1/NABP2 are more abundant than complexes containing SOSS-B2/NABP1. Interacts with INTS3; the interaction is direct (By similarity). Localizes to nuclear foci following DNA damage. Belongs to the SOSS-C family. Extended N-terminus. Extended N-terminus.