Overexpression of a mammalian ethanolamine-specific kinase accelerates the CDP-ethanolamine pathway

J Biol Chem. 2001 Jan 19;276(3):2174-9. doi: 10.1074/jbc.M008794200. Epub 2000 Oct 23.

Abstract

Ethanolamine kinase (EKI) is the first committed step in phosphatidylethanolamine (PtdEtn) biosynthesis via the CDP-ethanolamine pathway. We identify a human cDNA encoding an ethanolamine-specific kinase EKI1 and the structure of the EKI1 gene located on chromosome 12. EKI1 overexpression in COS-7 cells results in a 170-fold increase in ethanolamine kinase-specific activity and accelerates the rate of [3H]ethanolamine incorporation into PtdEtn as a function of the ethanolamine concentration in the culture medium. Acceleration of the CDP-ethanolamine pathway does not result in elevated cellular PtdEtn levels, but rather the excess PtdEtn is degraded to glycerophosphoethanolamine. EKI1 has negligible choline kinase activity in vitro and does not influence phosphatidylcholine biosynthesis. Acceleration of the CDP-ethanolamine pathway also does not change the rate of PtdEtn formation via the decarboxylation of phosphatidylserine. The data demonstrate the existence of separate ethanolamine and choline kinases in mammals and show that ethanolamine kinase can be a rate-controlling step in PtdEtn biosynthesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Cytidine Diphosphate / analogs & derivatives*
  • Cytidine Diphosphate / metabolism*
  • DNA, Complementary
  • Ethanolamines / metabolism*
  • Humans
  • Molecular Sequence Data
  • Phospholipids / metabolism
  • Phosphotransferases (Alcohol Group Acceptor) / chemistry
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Sequence Homology, Amino Acid

Substances

  • DNA, Complementary
  • Ethanolamines
  • Phospholipids
  • CDP ethanolamine
  • Cytidine Diphosphate
  • Phosphotransferases (Alcohol Group Acceptor)
  • ethanolamine kinase

Associated data

  • GENBANK/AF207600