Anti-USP39 antibodies are used in the immunodetection of the protein ubiquitin specific peptidase 39. In humans, the canonical protein has a reported length of 565 amino acid residues and a mass of 65.4 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 Peptidase C19 protein family, USP39 is reported to play a role in in pre-mRNA splicing as a component of the U4/U6-U5 tri-snRNP, one of the building blocks of the precatalytic spliceosome. Synonyms for this target antigen include CGI-21, HSPC332, SAD1, SNRNP65, U4/U6.U5 tri-snRNP-associated protein 2, and 65K.