Anti-SF3B3 antibodies are used in the immunodetection of the protein splicing factor 3b subunit 3. In humans, the canonical protein has a reported length of 1217 amino acid residues and a mass of 135.6 kDa. Its subcellular localization is in the nucleus. Alternative splicing is reported to yield 3 different isoforms for this protein. A member of a the RSE1 protein family, SF3B3 is known to be involved in pre-mRNA splicing as a component of the splicing factor SF3B complex, a constituent of the spliceosome. Synonyms for this target antigen include SAP130, SF3b130, STAF130, SAP 130, pre-mRNA splicing factor SF3b, 130 kDa subunit, and RSE1.