Aminopeptidase N (APN; CD13) is a zinc-dependent integral ectopeptidase composed of 967 amino acids, with a molecular mass of 160 kDa that cleaves neutral amino acids from the N-terminal of peptides.[1][2] It has been implicated in coronovirus invasion of cells of the respiratory tract, cardiovascular disease, diabetic nephropathy, rheumatoid arthritis, inflammatory bowel disease and numerous cancers.[1][3][4] Its expression in cancer cells has been associated with more aggressive phenotypes and a role for it has been determined in: leukaemia, breast cancer, colon cancer, stomach cancer, non-small cell lung cancer, kidney cancer, ovarian cancer, pancreatic cancer and thryoid cancer.[1] It is also an enkephalinase, that is, it is an enzyme involved in the degradation of enkephalins, such as met-enkephalin and leu-enkephalin.[5] Additional roles in immunity have also been discovered (such as in the degradation of the pro-inflammatory cytokines, interleukin-8 and N-formyl-methionine-leucine-phenylalanine and in the regulation of T cell function[6]) and the use of APN inhibitors has been proposed as a potential drug therapy for inflammatory bowel disease and rheumatoid arthritis.[3][7] It is found in abundance in the central nervous system, liver, mucosal layer of the small intestine and kidneys.[8][9]
APN is inhibited by Ezetimibe which is used as high blood cholesterol medication.
