Anti-U2SURP antibodies are used in the immunodetection of the protein U2 snRNP associated SURP domain containing. In humans, the canonical protein has a reported length of 1029 amino acid residues and a mass of 118.3 kDa. Its subcellular localization is in the nucleus. Alternative splicing is reported to yield 3 different isoforms for this protein. The U2SURP protein is a member of the Splicing factor SR protein family. Synonyms for this target antigen include fSAPa, U2 snRNP-associated SURP motif-containing protein, 140 kDa Ser/Arg-rich domain protein, Ser/Arg-rich domain protein, 140 kDa, and SR140.