Discovery and characterization of a Ca2+-independent phosphatidylethanolamine N-acyltransferase generating the anandamide precursor and its congeners

J Biol Chem. 2007 Feb 9;282(6):3614-23. doi: 10.1074/jbc.M606369200. Epub 2006 Dec 7.


N-Acylphosphatidylethanolamines (NAPEs) are precursors of bioactive N-acylethanolamines, including the endocannabinoid anandamide. In animal tissues, NAPE is formed by transfer of a fatty acyl chain at the sn-1 position of glycerophospholipids to the amino group of phosphatidylethanolamine (PE), and this reaction is believed to be the principal rate-limiting step in N-acylethanolamine synthesis. However, the Ca2+-dependent, membrane-associated N-acyltransferase (NAT) responsible for this reaction has not yet been cloned. In this study, on the basis of the functional similarity of NAT to lecithin-retinol acyltransferase (LRAT), we examined a possible PE N-acylation activity in two rat LRAT homologous proteins. Upon overexpression in COS-7 cells, one protein, named rat LRAT-like protein (RLP)-1, catalyzed transfer of a radioactive acyl group from phosphatidylcholine (PC) to PE, resulting in the formation of radioactive NAPE. However, the RLP-1 activity was detected mainly in the cytosolic rather than membrane fraction and was little stimulated by Ca2+. Moreover, RLP-1 did not show selectivity with respect to the sn-1 and sn-2 positions of PC as an acyl donor and therefore could generate N-arachidonoyl-PE (anandamide precursor) from 2-arachidonoyl-PC and PE. In contrast, under the same assay conditions, partially purified NAT from rat brain was highly Ca2+-dependent, membrane-associated, and specific for the sn-1-acyl group of PC. RLP-1 mRNA was expressed predominantly in testis among various rat tissues, and the testis cytosol exhibited an RLP-1-like activity. These results reveal that RLP-1 can function as a PE N-acyltransferase, catalytically distinguishable from the known Ca2+-dependent NAT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / chemistry*
  • Acyltransferases / metabolism
  • Amino Acid Sequence
  • Animals
  • Arachidonic Acids / chemistry*
  • Arachidonic Acids / metabolism
  • COS Cells
  • Calcium / physiology*
  • Chlorocebus aethiops
  • Endocannabinoids
  • Male
  • Molecular Sequence Data
  • Phosphatidylcholines / metabolism
  • Polyunsaturated Alkamides / chemistry*
  • Polyunsaturated Alkamides / metabolism
  • Rats
  • Rats, Wistar
  • Sequence Homology, Amino Acid
  • Testis / enzymology


  • Arachidonic Acids
  • Endocannabinoids
  • Phosphatidylcholines
  • Polyunsaturated Alkamides
  • Acyltransferases
  • phosphatidylethanolamine N-acyltransferase
  • RLP-1 protein, rat
  • lecithin-retinol acyltransferase
  • Calcium
  • anandamide

Associated data

  • GENBANK/AB255646