Broad specificity aminopeptidase which plays a role in the final digestion of peptides generated from hydrolysis of proteins by gastric and pancreatic proteases. Also involved in the processing of various peptides including peptide hormones, such as angiotensin III and IV, neuropeptides, and chemokines. May also be involved the cleavage of peptides bound to major histocompatibility complex class II molecules of antigen presenting cells. May have a role in angiogenesis and promote cholesterol crystallization. May have a role in amino acid transport by acting as binding partner of amino acid transporter SLC6A19 and regulating its activity (By similarity). (Microbial infection) Acts as a receptor for human coronavirus 229E/HCoV-229E. In case of human coronavirus 229E (HCoV-229E) infection, serves as receptor for HCoV-229E spike glycoprotein. (Microbial infection) Mediates as well Human cytomegalovirus (HCMV) infection. Release of an N-terminal amino acid, Xaa-|-Yaa- from a peptide, amide or arylamide. Xaa is preferably Ala, but may be most amino acids including Pro (slow action). When a terminal hydrophobic residue is followed by a prolyl residue, the two may be released as an intact Xaa-Pro dipeptide. Binds 1 zinc ion per subunit. Homodimer. Interacts with SLC6A19 (By similarity). (Microbial infection) Interacts with the S1 domain of human coronavirus 229E/HCoV-229E spike protein. Also found as a soluble form. Expressed in epithelial cells of the kidney, intestine, and respiratory tract; granulocytes, monocytes, fibroblasts, endothelial cells, cerebral pericytes at the blood-brain barrier, synaptic membranes of cells in the CNS. Also expressed in endometrial stromal cells, but not in the endometrial glandular cells. Found in the vasculature of tissues that undergo angiogenesis and in malignant gliomas and lymph node metastases from multiple tumor types but not in blood vessels of normal tissues. A soluble form has been found in plasma. It is found to be elevated in plasma and effusions of cancer patients. Estradiol and IL8/interleukin-8 decrease enzymatic activity in vitro in endometrial stromal cells by 40% and 30%, respectively. Sulfated. N- and O-glycosylated. May undergo proteolysis and give rise to a soluble form. Found to serve as a receptor for tumor-homing peptides, more specifically NGR peptides. It could serve thus as a target for delivering drugs into tumors. Concentration in human hepatic bile, varies from 17.3 to 57.6 micrograms/ml. Belongs to the peptidase M1 family.