Aminopeptidase with specificity towards an acidic amino acid at the N-terminus. Plays a role in membrane trafficking and is specifically involved in the recycling and degradation of endocytic cargo. Release of an N-terminal aspartate or glutamate from a peptide, with a preference for aspartate. Binds 2 Zn(2+) ions per subunit. Tetrahedron-shaped homododecamer built from six homodimers. Diffuse expression in the cytosol. Expressed in various cell types and tissues including the pharynx, neurons, body wall muscle, intestine and vulva. Expressed from the embryonic stage to adulthood. Animals are viable. Suppresses the abnormal formation of intestinal vacuoles phenotype in mutants lacking the phospholipid-transporting ATPase tat-1 or its chaperone chat-1. Belongs to the peptidase M18 family.