ENTPD1(Ectonucleoside triphosphate diphosphohydrolase 1) is also named as CD39,NTPDase 1,Ecto-ATPDase 1 and belongs to the GDA1/CD39 NTPase family. In the nervous system,it can hydrolyze ATP and other nucleotides to regulate purinergic neurotransmission.It is a noncovalent tetrameric protein and that detergent inhibition of enzymatic activity is caused by dissociation of ectoapyrase tetramers into monomers.And it is a 70- to 100-kDa protein that is heavily N-glycosylated. This protein has 6 glycosylation sites and 3 isoforms(58 kDa,59 kDa and 34 kDa) produced by alternative splicing. The soluble isoform of CD39(38-478 amino acid) locates to the extracellular part and this antibody can recognize the soluble form of CD39 (38-478aa) molecule.