Peptidase M3 thimet oligopeptidase (TOP), also includes neurolysin
Peptidase M3 Thimet oligopeptidase (TOP; PZ-peptidase; endo-oligopeptidase A; endopeptidase 24.15; soluble metallo-endopeptidase; EC 3.4.24.15) family also includes neurolysin (endopeptidase 24.16, microsomal endopeptidase, mitochondrial oligopeptidase M, neurotensin endopeptidase, soluble angiotensin II-binding protein, thimet oligopeptidase II) which hydrolyzes oligopeptides such as neurotensin, bradykinin and dynorphin A. TOP and neurolysin are neuropeptidases expressed abundantly in the testis, but are also found in the liver, lung and kidney. They are involved in the metabolism of neuropeptides under 20 amino acid residues long and cleave most bioactive peptides at the same sites, but recognize different positions on some naturally occurring and synthetic peptides; they cleave at distinct sites on the 13-residue bioactive peptide neurotensin, which modulates central dopaminergic and cholinergic circuits. TOP has been shown to degrade peptides released by the proteasome, limiting the extent of antigen presentation by major histocompatibility complex class I molecules, and has been associated with amyloid protein precursor processing.