Hydrolase that metabolizes extracellular nucleotides, including ATP, GTP, UTP and CTP (By similarity). Limits mast cell and basophil responses during inflammation and during the chronic phases of allergic responses by eliminating the extracellular ATP that functions as signaling molecule and activates basophils and mast cells and induces the release of inflammatory cytokines. Metabolizes extracellular ATP in the lumen of the small intestine, and thereby prevents ATP-induced apoptosis of intestinal plasmacytoid dendritic cells (By similarity). Has also alkaline phosphodiesterase activity (By similarity). Hydrolytically removes 5'-nucleotides successively from the 3'-hydroxy termini of 3'-hydroxy-terminated oligonucleotides. a ribonucleoside 5'-triphosphate + H2O = a ribonucleoside 5'-phosphate + diphosphate + H(+) a 2'-deoxyribonucleoside 5'-triphosphate + H2O = a 2'-deoxyribonucleoside 5'-phosphate + diphosphate + H(+) Binds 2 zinc ions per subunit. Monomer and homodimer. Detected at the cell surface of basophils. Detected at the apical plasma membrane of bile duct cells. Located to the apical surface in intestinal and kidney epithelial cells. Secreted in serum, and in lumen of epithelial cells. N-glycosylated. N-glycosylation is necessary for normal transport to the cell membrane, but is not the apical targeting signal.