THE ROLE OF PHOSPHATIDYLSERINE DECARBOXYLASE IN BRAIN PHOSPHOLIPID-METABOLISM
THE ROLE OF PHOSPHATIDYLSERINE DECARBOXYLASE IN BRAIN PHOSPHOLIPID-METABOLISM
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DOI：
10.1111/j.1471-4159.1983.tb00844.x
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发表时间：
1983-01-01
影响因子：
4.7
通讯作者：
MORELL, P
中科院分区：
文献类型：
--
作者：
BUTLER, M;MORELL, P
在大鼠脑中，磷脂酰乙醇胺可以从游离乙醇胺合成，或者通过涉及CDP-乙醇胺的形成及其转移到甘油二酯的途径，或者通过乙醇胺与现有磷脂的碱交换。虽然从丝氨酸的从头合成也已被证明，涉及的代谢途径是未知的。磷脂酰丝氨酸脱羧酶似乎参与了肝脏中大部分磷脂酰乙醇胺的合成，但这一途径在大脑中的意义受到了挑战。体外研究表明，在大鼠脑中存在磷脂酰丝氨酸脱羧酶活性，并表征其某些性质。这种酶定位于线粒体部分，而参与碱基交换和胞苷途径的酶定位于微粒体膜。平行的体内研究表明，颅内注射L-[G-3 H]丝氨酸后，磷脂酰丝氨酸的比活性在微粒体组分中比在线粒体组分中更大;磷脂酰乙醇胺则相反。当同时注射L-[U-14 C]丝氨酸和[1- 3 H]乙醇胺时，线粒体磷脂酰乙醇胺中的14 C/3 H比是微粒体磷脂酰乙醇胺中的10倍。结果表明，丝氨酸主要通过脑线粒体中磷脂酰丝氨酸的脱羧作用被掺入磷脂酰乙醇胺的碱基部分。磷脂酰丝氨酸脱羧酶对全脑磷脂酰乙醇胺合成的贡献的最小值为7%，可以从体内数据中估计。
In rat brain, phosphatidylethanolamine can be synthesized from free ethanolamine either by a pathway involving the formation of CDP-ethanolamine and its transfer to diglyceride, or by base-exchange of ethanolamine with existing phospholipids. Although de novo synthesis from serine has also been demonstrated, the metabolic pathway involved is not known. The enzyme phosphatidylserine decarboxylase appears to be involved in the synthesis of much of the phosphatidylethanolamine in liver, but the significance of this route in the brain has been challenged. In vitro studies demonstrate the existence of phosphatidylserine decarboxylase activity in rat brain and characterize some of its properties. This enzyme is localized in the mitochondrial fraction, while the enzymes involved in base-exchange and the cytidine pathway are localized to microsomal membranes. Parallel in vivo studies showed that after the intracranial injection of L-[G-3H]serine, the specific activity of phosphatidylserine was greater in the microsomal fractions than in the mitochondrial fraction; the opposite was true for phosphatidylethanolamine. When L-[U-14C]serine and [1-3H]ethanolamine were simultaneously injected, the 14C/3H ratio in mitochondrial phosphatidylethanolamine was 10 times that in microsomal phosphatidylethanolamine. The results demonstrate that serine is incorporated into the base moiety of phosphatidylethanolamine primarily through the decarboxylation of phosphatidylserine in brain mitochondria. A minimal value of 7% for the contribution of phosphatidylserine decarboxylase to whole-brain phosphatidylethanolamine synthesis can be estimated from the in vivo data.