Effect of modification of membrane phospholipid composition on the activity of phosphatidylethanolamine N-methyltransferase of Tetrahymena

摘要: Abstract The activity of phosphatidylethanolamine N -methyltransferase is less than 10% control levels in microsomes prepared from the ciliate protozoan Tetrahymena thermophila whose phospholipid composition had been altered by being cultured on media containing phosphonic acids. primary modification obtained decreased ( J. D. Smith and A. Giegel, Arch. Biochem. Biophys. , 206 420–423 (1981) 213 595–601 (1982)). enzyme protein present these cells at normal since addition substrate to assay system restores lipid-modified levels, while not affected added phosphatidylethanolamine. microsomal inhibited anionic phospholipids cardiolipin, phosphatidylglycerol, phosphatidylinositol lysophosphatidylethanolamine it activated only phosphatidylserine substrates phosphatidyldimethylethanolamine. acts directly as a for methyltransferase rather acting merely stimulating utilization endogenous lipid phosphatidyl[ 14 C]ethanolamine converted phosphatidylcholine. results suggest that technique acid-induced will be useful study other membrane-bound enzymes.