NTPDase (外核苷三磷酸二磷酸水解酶)

Ectonucleoside triphosphate diphosphohydrolase (NTPDase), belonging to the CD39/apyrase family of hydrolases, exists in various organisms including mammals, plants, yeast, and protozoa. NTPDase catalyzes the hydrolysis of nucleoside triphosphates (such as ATP, GTP) and diphosphates (such as ADP, GDP) to produce corresponding nucleoside monophosphates (such as AMP, GMP) and inorganic phosphate (Pi). Additionally, NTPDase participates in the dynamic balance of purinergic signaling pathways by regulating extracellular nucleotide levels.
There are 8 subtypes of NTPDase (NTPDase1-8). Members of this family that are localized to the cell surface are able to regulate the concentration of nucleotides that act as agonists for purinergic and pyrimidinergic receptor signaling. Among them, NTPDase4 and NTPDase7 are located on the inner membrane of cells. NTPDase5 and NTPDase6 are also present in the inner membrane, but after their single N-terminal transmembrane signal sequence is cleaved, they can be secreted in a soluble form. Furthermore, NTPDase1 (also known as CD39) and NTPDase2 (also known as ecto-ATPase), NTPDase3 (also known as HB6 or CD39L3), and NTPDase8 are all located on the cell surface membrane with their active sites located extracellularly. These cell surface nucleotidases are capable of hydrolyzing extracellular nucleotides that activate purinergic receptors (P2X and P2Y), which conduct signaling through G proteins (metabotropic P2Y receptor family) or are themselves ligand-gated ion channels (ionic P2X receptor family).
NTPDase is involved in various physiological and pathological processes, including inflammation, vasodilation, tumor progression, and regulation of immune responses^[1][2][3].