Anti-proteasome 20S subunit beta 5 antibodies are used for the immunodetection of the protein encoded by the PSMB5 gene. In humans, the canonical protein has a reported length of 263 amino acid residues and a mass of 28.5 kDa. Its subcellular localization is in the nucleus and cytoplasm. Alternative splicing is reported to yield 3 different isoforms for this protein. A member of the Peptidase T1B protein family, it is a known component of the 20S core proteasome complex involved in the proteolytic degradation of most intracellular proteins. Other names for this target antigen include MB1, proteasome subunit beta type-5, PSX large multifunctional protease X, macropain epsilon chain, and LMPX. Gene orthologs have been identified in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.