Phospholipid synthesis in isolated fat cells. Studies of microsomal diacylglycerol cholinephosphotransferase and diacylglycerol ethanolaminephosphotransferase activities

J Biol Chem. 1977 May 10;252(9):3050-6.


Diacylglycerol cholinephosphotransferase (EC and diacylglycerol ethanolaminephosphotransferase (EC activities were investigated in microsomes from isolated rat fat cells. Assays based on the conversion of CDP-[14C]choline of CDP-[14C]ethanolamine to phosphatidylcholine or phosphatidylethanolamine utilized ethanol-dispersed diacylglycerols and 1 to 5 microng of protein. Cholinephosphotransferase and ethanolaminephosphotransferase activities had similar dependences on MgCl2 and pH, and were inhibited similarly by CaCl2, organic solvents, Triton X-100, Tween 20, and dithiothreitol. Ethylene glycol bis(beta-amino-ethyl ether)-N,N,N',N'-tetraacetic acid stimulated both activities similarly. With 1,2-dioleoyl-sn-glycerol, the cholinephosphotransferase activity had an apparent Km for CDP-choline of 23.9 micronM and a V max of 8.54 nmol/min/mg. CDP-ethanolamine and CDP were competitive inhibitors of the cholinephosphotransferase activity (apparent Kl values of 227 micronM and 360 micronM, respectively). With 1,2-dioleoyl-sn-glycerol, the ethanolaminephosphotransferase activity had an apparent Km of 18.3 micronM for CDP-ethanolamine and a V max of 1.14 nmol/min/mg. CDP-choline appeared to be a noncompetitive inhibitor of the ethanolaminephosphotransferase activity (apparent Kl of 1620 micronM). Inhibition of the ethanolaminephosphotransferase activity by CDP appeared to be of a mixed type. The dependences on diacylglycerols containing fatty acids 6 to 18 carbons in length were investigated...

Publication types

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

MeSH terms

  • Adipose Tissue / cytology
  • Adipose Tissue / enzymology*
  • Animals
  • Binding, Competitive
  • Cytidine Diphosphate Choline / pharmacology
  • Diacylglycerol Cholinephosphotransferase / antagonists & inhibitors
  • Diacylglycerol Cholinephosphotransferase / metabolism*
  • Diglycerides / pharmacology
  • Drug Stability
  • Ethanolamines / pharmacology
  • Female
  • Hot Temperature
  • Kinetics
  • Microsomes / enzymology*
  • Phospholipids / biosynthesis*
  • Phosphotransferases / antagonists & inhibitors
  • Phosphotransferases / metabolism*
  • Rats
  • Structure-Activity Relationship


  • Diglycerides
  • Ethanolamines
  • Phospholipids
  • Cytidine Diphosphate Choline
  • Phosphotransferases
  • Diacylglycerol Cholinephosphotransferase