Aminopeptidase with broad substrate specificity. Has lower activity with substrates that have Asp or Glu in the P2' position, or Pro in the P3' position. Lacks activity with substrates that have both Pro in the P3' position and Asp or Glu in the P2' position. Lacks carboxypeptidase activity. Lacks dipeptidyl-peptidase IV type activity. Binds 2 Zn(2+) ions per subunit. Homodimer. Ileal brush border membrane. Detected on apical villi on the brush border membrane of ileum enterocytes (at protein level) (PubMed:9388249). Mainly expressed in the distal small intestine (PubMed:9388249). N-glycosylated. Belongs to the peptidase M28 family. M28B subfamily.