Aminopeptidase
Aminopeptidases are enzymes that catalyze the cleavage of amino acids from the N-terminus (beginning), of proteins or peptides. They are found in many organisms; in the cell, they are found in many organelles, in the cytosol (internal cellular fluid), and as membrane proteins. Aminopeptidases are used in essential cellular functions, and are often zinc metalloenzymes, containing a zinc cofactor.
Crystal structure of the open state of human endoplasmic reticulum aminopeptidase 1 ERAP1 | |||||||||
| Identifiers | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | Peptidase_M1 | ||||||||
| Pfam | PF01433 | ||||||||
| MEROPS | M1 | ||||||||
| OPM superfamily | 227 | ||||||||
| OPM protein | 3mdj | ||||||||
| CDD | cd09595 | ||||||||
| Membranome | 534 | ||||||||
| |||||||||
Aminopeptidases occur in both water-soluble and membrane-bound forms and can be found both in various cellular compartments and in the extracellular environment (outside of cells). Their broad substrate specificity, their ability to strongly bind to their targets, allows them to remove beginning N-terminal amino acids from almost all unsubstituted oligopeptides. For instance, Aminopeptidase N (AP-N) is particularly abundant in the brush border membranes of the kidney, the small intestine, and the placenta, and is also found in the liver. AP-N is involved in the final digestion of peptides generated from the hydrolysis (cleaving) of proteins by gastric and pancreatic proteases.
Some aminopeptidases are monomeric, and others are found as assemblies of relatively high mass (50 kDa) subunits. cDNA sequences are available for several aminopeptidases and a crystal structure of the open state of human endoplasmic reticulum aminopeptidase 1 is available.