CD39, also known as ectonucleoside triphosphate diphosphohydrolase 1 (ENP1), is an integral membrane glycoprotein that acts as an extracellular nucleotide-hydrolyzing enzyme. CD39 inhibits ADP-induced platelet aggregation by hydrolyzing ADP to AMP and ultimately generating adenosine. Intracellular CD39 undergoes glycosylation at 6 N-glycosylation sites and translocates to the membrane in order to be an active enzyme. CD39L1 is a 495 amino acid multi-pass membrane protein that requires calcium and magnesium cofactors to hydrolyze ATP and other nucleotides in the regulation of purigenic neurotransmission. CD39L1 is expressed in kidney, colon, heart, testis, pancreas, brain, prostate, skeletal muscle, small intestine and ovaries. There are two isoforms of CD39L1 that are produced as a result of alternative splicing events.