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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/2941

Title: Identification and characterization of a novel hepatic canalicular ATP diphosphohydrolase
Authors: Sevigny, J
Robson, SC
Waelkens, E
Csizmadia, E
Smith, RN
Issue Date: 2000
Citation: JOURNAL OF BIOLOGICAL CHEMISTRY, 275(8). p. 5640-5647
Abstract: We have identified and characterized a novel ATP diphosphohydrolase (ATPDase) with features of E-type ATPases from porcine liver. Immunoblotting with a specific monoclonal antibody to this ectoenzyme revealed high expression in liver with lesser amounts in kidney and duodenum. This ATPDase was localized by immunohistochemistry to the bile canalicular domain of hepatocytes and to the luminal side of the renal ductular epithelium, In contrast, ATPDase/cd39 was detected in vascular endothelium and smooth muscle in these organs, We purified the putative ATPDase from liver by immunoaffinity techniques and obtained a heavily glycosylated protein with a molecular mass estimated at 75 kDa. This enzyme hydrolyzed all tri- and diphospho-nucleosides but not AMP or diadenosine polyphosphates, There was an absolute requirement for divalent cations (Ca2+ > Mg2+). Biochemical activity was unaffected by sodium azide or other inhibitors of ATPases, Kinetic parameters derived from purified preparations of hepatic ATPDase indicated V-max of 8.5 units/mg of protein with apparent K-m of 100 mu M for both ATP or ADP as substrates. NH2-terminal amino acid sequencing revealed near 50% identity with rat liver lysosomal (Ca2+-Mg2+)-ATPase. The different biochemical properties and localization of the hepatic ATPDase suggest pathophysiological functions that are distinct from the vascular ATPDase/cd39.
Notes: Harvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Dept Med, Boston, MA 02215 USA. Harvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Dept Surg, Boston, MA 02215 USA. Katholieke Univ Leuven, Dept Biochem, B-3000 Louvain, Belgium. Massachusetts Gen Hosp, Immunopathol Unit, Dept Pathol, Boston, MA 02114 USA. Limburgs Univ Ctr, Dept MBW, B-3590 Diepenbeek, Belgium.Sevigny, J, Harvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Dept Med, 99 Brookline Ave,R 359, Boston, MA 02215 USA.
URI: http://hdl.handle.net/1942/2941
ISI #: 000085474500054
ISSN: 0021-9258
Category: A1
Type: Journal Contribution
Validation: ecoom, 2001
Appears in Collections: Research publications

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