Alternative pathways for phosphatidylcholine synthesis in olive (Olea europaea L.) callus cultures.
Olive (Olea europaea L.) callus cultures were incubated with [2-14C]ethanolamine and [Me-14C]choline in order to study phospholipid synthesis. Radioactivity from [Me-14C]choline was shown to be incorporated into the phosphatidylcholine via the CDP-base pathway. [2-14C]Ethanolamine was primarily incorporated into phosphatidylethanolamine, but significant radio-activity was also detected in phosphatidylcholine, indicating the operation of a methylation route. Incubation with [2-14C]ethanolamine indicated that phosphatidylcholine and phosphatidylethanolamine incorporated radiolabel over a similar time course. This led us to investigate the possibility that phosphatidylcholine was being synthesized by a methylation pathway distinct from the direct methylation of phosphatidylethanolamine. There was extensive incorporation of [2-14C]ethanolamine into different components of the aqueous phase of the incubations, within which phospho-base derivatives of ethanolamine were prominent. These intermediates were identified and provided evidence for the operation of an alternative methylation pathway via phosphodimethylethanolamine for the biosynthesis of phosphatidylcholine in olives.
Williams
M
M
School of Molecular and Medical Biosciences, University of Wales College of Cardiff, Wales, U.K.
Harwood
J L
JL
D002250:Carbon Radioisotopes; D002794:Choline / Q000378:metabolism; D046508:Culture Techniques; D019856:Ethanolamine; D004983:Ethanolamines / Q000378:metabolism; D005638:Fruit / Q000378:metabolism; D007700:Kinetics; D008745:Methylation; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D010714:Phosphatidylethanolamines / Q000096:biosynthesis; D010944:Plants / Q000378:metabolism*
D002250:Carbon Radioisotopes; D004983:Ethanolamines; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D019856:Ethanolamine; D002794:Choline