Anti-Cathepsin E antibodies are used in the immunodetection of the protein encoded by the CTSE gene. In humans, the canonical protein has a reported length of 396 amino acid residues and a mass of 42.8 kDa. Its subcellular localization is in the endosome. Alternative splicing is reported to yield 3 different isoforms for this protein. It is noted to be expressed abundantly in the stomach, the Clara cells of the lung and activated B-lymphocytes, and at lower levels in lymph nodes, skin and spleen. A member of the Peptidase A1 protein family, it is suspected to have a role in immune function. Post-translational modifications have been described, including glycosylation and protein cleavage. Other names for this target antigen include erythrocyte membrane aspartic proteinase, slow-moving proteinase, and CATE.