title: Ecto-ATPase.
abstract: An ecto-adenosine triphosphatase (E.C. 3.6.1.4 ATP-phosphohydrolase) is shown to be localized on the outer surface of varieties of cell membrane. The enzyme is different from the ATPase involved in biological energy transduction and ion transport mechanism. The characteristic of the enzyme lies in having a very broad substrate specificity and is inhibited by EDTA and higher concentration of ATP. The enzyme is dependent on bivalent metal ions, Mg++ or Ca++ for its optimum activity. The enzyme is highly sensitive to SH-reagents but insensitive to inhibitors of mitochondrial ATPase or Na+- K+- ATPase. The possible functions of the enzyme in being oriented outside the cell membrane is discussed.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D008274:Magnesium / Q000378:metabolism; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology
chemical_list: D013438:Sulfhydryl Compounds; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D000251:Adenosine Triphosphatases; C027201:ectoATPase; D008274:Magnesium; D002118:Calcium