Tijburg L B, Geelen M J, Van Golde L M
Laboratory of Veterinary Biochemistry, University of Utrecht, The Netherlands.
Biochem Biophys Res Commun. 1989 May 15;160(3):1275-80. doi: 10.1016/s0006-291x(89)80141-x.
In the present study pulse-label and pulse-chase experiments with isolated rat hepatocytes in suspension were designed to investigate the effects of the presence of either serine or ethanolamine in the medium on the rate of phosphatidylethanolamine synthesis via the CDPethanolamine pathway and by decarboxylation of phosphatidylserine. Addition of serine to the medium did not affect the incorporation of [1,2-14C]ethanolamine into phosphatidylethanolamine. Pulse-label experiments showed that the incorporation of [3H]serine into phosphatidylserine decreased in the presence of ethanolamine with a corresponding decrease of the incorporation of label into the ethanolamine base moiety of phosphatidylethanolamine. However, the radioactivity in the diacylglycerol part of phosphatidylethanolamine was considerably higher in the presence of ethanolamine than in its absence. Pulse-chase experiments with labelled serine demonstrated that the conversion of phosphatidylserine to phosphatidylethanolamine was not affected by varying concentrations of ethanolamine. Our observations indicate that in the presence of ethanolamine the biosynthesis of phosphatidylethanolamine via the CDPethanolamine pathway is enhanced relative to the synthesis by decarboxylation of phosphatidylserine.
在本研究中，设计了悬浮培养的分离大鼠肝细胞的脉冲标记和脉冲追踪实验，以研究培养基中丝氨酸或乙醇胺的存在对通过CDP乙醇胺途径以及磷脂酰丝氨酸脱羧作用合成磷脂酰乙醇胺的速率的影响。向培养基中添加丝氨酸不会影响[1,2-14C]乙醇胺掺入磷脂酰乙醇胺。脉冲标记实验表明，在有乙醇胺存在的情况下，[3H]丝氨酸掺入磷脂酰丝氨酸的量减少，同时标记物掺入磷脂酰乙醇胺的乙醇胺碱基部分的量也相应减少。然而，在有乙醇胺存在的情况下，磷脂酰乙醇胺的二酰甘油部分的放射性比不存在乙醇胺时高得多。用标记丝氨酸进行的脉冲追踪实验表明，磷脂酰丝氨酸向磷脂酰乙醇胺的转化不受不同浓度乙醇胺的影响。我们的观察结果表明，在有乙醇胺存在的情况下，相对于通过磷脂酰丝氨酸脱羧作用的合成，通过CDP乙醇胺途径合成磷脂酰乙醇胺的生物合成增强。
