Serine and ethanolamine incorporation into different plasmalogen pools: subcellular analyses of phosphoglyceride synthesis in cultured glioma cells.
In cultured glioma cells, plasma membrane (PM) is enriched in phosphatidylserine (PtdSer) and plasmalogens (1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine). Serine can be a precursor of headgroups of both PtdSer and ethanolamine phosphoglycerides (PE) including plasmalogens and non-plasmalogen PE (NP-PE). Synthesis of phospholipids was investigated at the subcellular level using established fractionation procedures and incorporation of [3H(G)]L-serine and [1,2-14C]ethanolamine. Specific radioactivity of PtdSer from [3H]serine was 2-fold greater in PM than in microsomes, reaching maximum by 2-4 h. Labeled plasmalogen from [3H]serine appeared in PM by 4 h and increased to 48 h, whereas almost no plasmalogen accumulated in microsomes within 12 h. In contrast, labeled plasmalogen from [1,2-14C]ethanolamine appeared in both PM and microsomes at early incubation times and became enriched in PM beyond 12 h. Thus, in glioma cells: (1) greater and faster accumulation of labeled PtdSer in PM may reflect direct synthesis from serine within PM; (2) PM is a major source of PtdSer for decarboxylation and PE synthesis; (3) NP-PE in both PM and microsome provides headgroup for synthesis of plasmalogen; and, (4) plasmalogen synthesis may involve different intracellular pools depending on headgroup origin.
Xu
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Atlantic Research Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
Byers
D M
DM
Palmer
F B
FB
Cook
H W
HW
D000818:Animals; D002250:Carbon Radioisotopes; D002460:Cell Line; D019856:Ethanolamine; D004983:Ethanolamines / Q000378:metabolism*; D005910:Glioma / Q000378:metabolism*; D007700:Kinetics; D008861:Microsomes / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis; D010955:Plasmalogens / Q000096:biosynthesis*; D012694:Serine / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D014316:Tritium; D014407:Tumor Cells, Cultured
D002250:Carbon Radioisotopes; D004983:Ethanolamines; D010743:Phospholipids; D010955:Plasmalogens; D014316:Tritium; D012694:Serine; D019856:Ethanolamine