Members of the ecto-nucleoside triphosphate diphosphohydrolase (eNTPDase) protein family are glycosylated enzymes that hydrolyze nucleoside 5’-triphosphates and 5’-diphosphates in extracellcular space. The enzymatic activities of eNTPDase are dependent on cations such as magnesium and calcium. Members of this protein family differ in their affinities for triphosphates versus diphosphates as substrate material. CD39L3，also known as Ectonucleoside triphosphate diphosphohydrolase 3 or NTPDase 3，is a 529 amino acid multi-pass membrane protein that has a three-fold preference for hydrolysis of ATP over ADP. Both calcium and magnesium serve as cofactors for CD39L3’s extremely active extracellular nucleotide hydrolysis site. CD39L3 is expressed in spleen，prostate，brain and pancreas，though moderate to low expression is observed in most tissues，with the exception of liver and peripheral blood leukocytes.