ENTPD1 is an integral membrane protein with an extracellular active site. ENTPD1 hydrolyzes the beta - and gamma phosphate residues of nucleotides, preferring ATP as the substrate. Through its hydrolysis of extracellular nucleotides, ENTPD1 plays a role in the regulation of purinergic signaling. CD39 Protein, Cynomolgus/Rhesus Macaque (sf9, His) is the recombinant Rhesus Macaque-derived CD39 protein, expressed by Sf9 insect cells , with C-His labeled tag.