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 (PubMed:25692702). Metabolizes extracellular ATP in the lumen of the small intestine, and thereby prevents ATP-induced apoptosis of intestinal plasmacytoid dendritic cells (PubMed:28225814). 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 (PubMed:25692702). 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 (By similarity). Detected at the tip of villi in the small intestine (PubMed:28225814). Detected on basophils and mast cells (at protein level) (PubMed:25692702). Detected in the epithelial layer of the small intestine; expression is higher in the proximal part and lower in the distal part of the small intestine (PubMed:28225814). In bone marrow-derived mast cells and basophils, induced by activation of the high affinity immunoglobulin epsilon receptor 1 (Fc epsilon RI). N-glycosylated. N-glycosylation is necessary for normal transport to the cell membrane, but is not the apical targeting signal. Mice appear healthy, and have normal numbers of peripheral lymphocytes, eosinophils and neutrophils. Basophil numbers are normal in bone marrow, but are markedly increased in peripheral blood and spleen. Likewise, mutant mice have an increased number of mast cells in the small and large intestine. Both mast cells and basophils show increased proliferation in response to extracellular ATP. Mutant mice display normal immediate reaction to allergens, but strongly increased chronic allergic inflammation in skin, intestine and lung that lead to severe tissue damage. Extracellular ATP levels are normal in the absence of allergen, and strongly increased after exposure to allergen, due to impaired clearance of extracellular ATP (PubMed:25692702). Mutant mice display increased levels of extracellular ATP in the lumen of the small intestine. They have decreased numbers of plasmacytoid dendritic cells in the small intestine lamia propria and in Peyer patches; the decrease is due to increased ATP levels that cause increased apoptosis of plasmacytoid dendritic cells (PubMed:28225814).