胆碱摄取及磷脂酰胆碱合成的调节研究

木文研究了多种氨基酸、乙醇胺和甲基乙醇胺对细胞摄取胆碱和合成磷脂酰胆碱（ＰＣ）的影响，发现多种氨基酸非竞争性地抑制细胞摄取胆碱。含胆碱代谢物的分析显示胆碱转变成ＣＤＰ－胆碱，随之形成ＰＣ均不受氨基酸影响。乙醇胺竞争性地抑制胆碱摄取，且存在剂量依赖关系。乙醇胺能明显抑制胆碱激酶活性，但细胞内胆碱和磷酸胆碱的代谢池并不改变，提示乙醇胺不影响胆碱转变成磷酸胆碱。根据ＣＤＰ－胆碱和ＰＣ的比放射性分布，乙醇胺也不影响ＰＣ的生物合成。甲基乙醇胺抑制胆碱摄入的程度强于乙醇胺，并抑制胆碱激酶和ＣＴＰ：磷酸胆碱胞苷转移酶活性，含胆碱代谢物以ＣＤＰ－胆碱下降最显著；提示甲基乙醇胺不仅抑制胆碱摄入而且还干扰了ＣＤＰ－胆碱通路。

Studies on the Regulation of Choline Uptake and Phosphatidylcholine Biosyntbesis

The effects of amino acids,ethanolamine and monomethylethanolamine on choline uptake and phosphatidylcholine biocynthesis in baby hamster kidney(BHK-21) cells were investigated.The uptake of labelled choline was noncompetitively inhibited by amino acids.The conversion of choline to CDP-choline and subsequently phosphatidyloholine was not affectid by the presence of amino acids.The uptake of choline was also competitively inhibited by ethanolamine.Although ethanolamine is a potent inhibitor of choline kinase,the conversion of choline to phosphocholine was not affected.Ethanolamine did not change the pool anes ofphosphoeholine and CDP-choline.As judged by the speeifie radioactivity of CDPcholine and the labelling of phosphatidylclioline,the rates of phosphatidylcholine biosynthesis were not significantly different between the control and the ethanolamine-treated cells.Monomethylethanolamine was more powerful in inhibiting choline uptake than ethanolamine,and also inhibited the activitied of choline kinase and CTP:phosphocholine cytidilyltransferabe.These results suggested that not only choline uptake, but abso the conversion of choline-containing compounds for the biosynthesis of phosphatidylcholine were disturbed by monomethylethanolamine.