Abstract
In this study, the isolated guinea pig heart was pulse-labeled with a precursor of ethanolamine glycerophospholipid, and then chased with the non-radioactive compound for 0-8 h. Labeling with hexadecanol revealed that plasmanylethanolamine was the immediate precursor of plasmenylethanolamine, but a substantial portion of the label was also found in phosphatidylethanolamine. When ethanolamine was used as the precursor, the labeling of plasmenylethanolamine was between 50-65% of the labeling of phosphatidylethanolamine, and this ratio was maintained throughout the perfusion. The ratio of labeling is similar to the ratio of pool sizes of these ethanolamine glycerophospholipid in the heart, which implies that the CDP-ethanolamine pathway is also important for plasmenylethanolamine biosynthesis. The role of diradylglycerol in the synthesis of each ethanolamine glycerophospholipid was also investigated. The ratio of 1-alkenyl-2-acyl glycerol to total diradylglycerol content was 7% in the homogenate and 32% in the microsomes. However, ethanolamine phosphotransferase displayed a distinct selectivity towards 1-alkenyl-2-acyl glycerol. Kinetic studies revealed that the synthesis of phosphatidylethanolamine was inhibited by 1-alkenyl-2-acyl glycerol, but the formation of plasmenylethanolamine was not affected by 1,2-diacylglycerol. In addition, the inhibition of ethanolamine phosphotransferase by 1-alkyl-2-acyl glycerol appears to be an important mechanism for the coordination of plasmenylethanolamine biosynthesis via the desaturase reaction and the CDP-ethanolamine pathway.
Highlights
In this study, the isolated guinea pig heart was pulse-labeled with a precursor of ethanolamine glycerophospholipid, and chased with the non-radioactive compound for 0-8 h
Plasmenylethanolamine is the major form of ethanolamine glycerophospholipid in the sarcoplasmic reticulum of certain cardiac tissues [8].Alternatively, plasmanylethanolamine is a minor phospholipid group in most tissues and generally accounts for heart, which implies that the CDP-ethanolamine pathway is important for plasmenylethanolamine biosynthesis
Lipids were extracted from the guinea pig heart and the content of each type of ethanolamine glycerophospholipid was determined (Table 1).Phosphatidylethanolamine (64%) and plasmenylethanolamine (35%) were major groups whereas plasmanylethanolamine (
Summary
The isolated guinea pig heart was pulse-labeled with a precursor of ethanolamine glycerophospholipid, and chased with the non-radioactive compound for 0-8 h. Plasmalogens have been postulated to be stabilizersof the membrane bilayer in bacteria [9] and facilitators of calcium translocation in sarcoplasmic reticulum [8].The presence of the vinyl ether group in ase by 1-alkyl-2-acylglycerol appears to be an important mech- the plasmalogen may protect animal cells from oxidaanism for the coordination of plasmenylethanolamine biosynthesis via the desaturase reaction and the CDP-ethanolamine pathway.-Xu, F. 1-0-alkyl-2-acyl-sn-glycero-3-phosphoethanolamisnue b strate for the production of the vinyl ether group ill Ethanolamine glycerophospholipid is a major phos- plasmenylethanolamine [13, 14]. The desaturase reacpholipid group in mammalian tissues [1].It consists of tion is highly specific and does not catalyze the formaa mixture of 1,2-diacyl-sn-glycero-3-phosphoethanolamine (phosphatidylethanolamine),1-0-alk-1’enyl-%acylsn-glycero-3-phosphoethanolamine(plasmenylethanolamine), and l-O-alkyl-2-acyl-sn-glycero-3-phospthhoaenolamine (plasmanylethanolamine) ( 2 ).
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