4naq
Crystal structure of porcine aminopeptidase-N complexed with poly-alanine
Structural highlights
FunctionAMPN_PIG Broad specificity aminopeptidase. Plays a role in the final digestion of peptides generated from hydrolysis of proteins by gastric and pancreatic proteases. May be involved in the metabolism of regulatory peptides of diverse cell types, responsible for the processing of peptide hormones, such as angiotensin III and IV, neuropeptides, and chemokines and involved the cleavage of peptides bound to major histocompatibility complex class II molecules of antigen presenting cells. May have a role in angiogenesis (By similarity). It is able to degrade Leu-enkephalin and Met-enkephalin but not cholecystokinin CCK8, neuromedin C (GRP-10), somatostatin-14, substance P and vasoactive intestinal peptide. In case of porcine transmissible gastroenteritis coronavirus (TGEV) and porcine respiratory coronavirus (PRCoV) infections, serves as a receptor for TGEV and PRCoV spike glycoprotein in a species-specific manner.[1] [2] [3] [4] [5] Publication Abstract from PubMedMammalian aminopeptidase N (APN) plays multifunctional roles in many physiological processes, including peptide metabolism, cell motility and adhesion, and coronavirus entry. Here we determined crystal structures of porcine APN at 1.85 A resolution and its complexes with a peptide substrate and a variety of inhibitors. APN is a cell surface-anchored and seahorse-shaped zinc-aminopeptidase that forms head-to-head dimers. Captured in a catalytically active state, these structures of APN illustrate a detailed catalytic mechanism for its aminopeptidase activity. The active site and peptide-binding channel of APN reside in cavities with wide openings, allowing easy access to peptides. The cavities can potentially open up further to bind the exposed N terminus of proteins. The active site anchors the N-terminal neutral residue of peptides/proteins, and the peptide-binding channel binds the remainder of the peptides/proteins in a sequence-independent fashion. APN also provides an exposed outer surface for coronavirus binding, without its physiological functions being affected. These structural features enable APN to function ubiquitously in peptide metabolism, interact with other proteins to mediate cell motility and adhesion, and serve as a coronavirus receptor. This study elucidates multifunctional roles of APN and can guide therapeutic efforts to treat APN-related diseases. Structural basis for multifunctional roles of mammalian aminopeptidase N.,Chen L, Lin YL, Peng G, Li F Proc Natl Acad Sci U S A. 2012 Oct 30;109(44):17966-71. doi:, 10.1073/pnas.1210123109. Epub 2012 Oct 15. PMID:23071329[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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