Identification and functional expression of four isoforms of ATPase II, the putative aminophospholipid translocase: Effect of isoform variation on the ATPase activity and phospholipid specificity

Jiantao Ding, Zhao Wu, Bill P. Crider, Yongming Ma, Xinji Li, Clive A. Slaughter, Limin Gong, Xiao Song Xie

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ATPaseII,avanadate-sensitiveandphosphatidylserine-dependent Mg2+-ATPase, is a member of a subfamily of P-type ATPase and is presumably responsible for amino-phospholipid translocation activity in eukaryotic cells. The aminophospholipid translocation activity plays an important physiological role in the maintenance of membrane phospholipid asymmetry that is observed in the plasma membrane as well as the membranes of certain cellular organelles. While the preparations of ATPase II from different sources share common fundamental properties, such as substrate specificity, inhibitor spectrum, and phospholipid dependence, they are divergent in several characteristics. These include specific ATPase activity and phospholipid selectivity. We report here the identification of four isoforms of ATPase II in bovine brain. These isoforms are formed by a combination of two major variations in their primary sequences and show that the structural variation of those isoforms has functional significance in both ATPase activity and phosholipid selectivity. Furthermore, studies with the phosphoenzyme intermediate of ATPase II and its recombinant isoforms revealed that phosphatidylserine is essential for the dephosphorylation of the intermediate. Without phosphatidylserine, ATPase II would be accumulated as phosphoenzyme in the presence of ATP, resulting in the interruption of its catalytic cycle.

Original languageEnglish (US)
Pages (from-to)23378-23386
Number of pages9
JournalJournal of Biological Chemistry
Issue number30
Publication statusPublished - Jul 28 2000
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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