Mediates the import of RPA complex into the nucleus, possibly via some interaction with importin beta. Isoform 2 is sumoylated and mediates the localization of RPA complex into the PML body of the nucleus, thereby participating in RPA function in DNA metabolism. Interacts with the RPA1 subunit of RPA complex. Widely expressed. Expressed in pancreas, kidney, muscle, liver, lung, placenta, brain, heart, leukocytes, colon, intestine, ovary, testis, prostate, thymus and spleen. Sumoylated. Sumoylation is required for localization in the nuclear PML body and transport of RPA complex in PML body. Upon UV irradiation and during S phase, it is desumoylated, releasing RPA complex that is translocated to sites of DNA damage. Sumoylation takes place at different Lys residues. Variant 'Lys-103' adds a sumoylation site and increases total sumoylation levels. Major isoform with isoform 2. Major isoform with isoform 1. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. May be due to an intron retention. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay.