NAALADL1 is a 740 amino acid single-pass type II membrane protein that localizes to the apical cell membrane. Belonging to the peptidase M28 family and the M28B subfamily, NAALADL1 is mainly expressed in the distal small intestine but is also expressed in spleen and tesits. NAALADL1 is considered a novel ileal brush border membrane protein,NAALADL1 is thought to have dipeptidyl-peptidase IV type activity. NAALADL1 exists as eight alternatively spliced isoforms and is encoded by a gene located on human chromosome 11q13.1.