Higgins J A, Fieldsend J K
J Lipid Res. 1987 Mar;28(3):268-78.
Phosphatidylcholine, the major phospholipid of very low density lipoproteins, is packaged with triglyceride in the Golgi cisternae. CTP-phosphocholine cytidyltransferase and CDP-choline phosphotransferase activities of Golgi subfractions were higher than those of rough or smooth microsomes measured under the same conditions, indicating that phosphatidylcholine synthesis can occur in Golgi membranes. Consistent with this, the specific activity of phosphatidylcholine of Golgi membranes rose more rapidly than that of rough and smooth microsomes after injection of [14C]choline in vivo. The specific activity of the Golgi content phosphatidylcholine (non-membrane fraction) remained low. The S-adenosylmethionine phosphatidylethanolamine methyltransferase activity of Golgi subfractions was also higher than that of rough or smooth microsomes. After injection of [3H]methyl-labeled methionine in vivo, the specific activity of phosphatidylcholine of the Golgi membranes rose in parallel with that of the rough and smooth microsomes. The specific activity of the Golgi content phosphatidylcholine rose above that of the Golgi membranes and exhibited a different pattern, suggesting that this pathway may selectively label phosphatidylcholine which is secreted as lipoproteins. These observations indicate that the Golgi membranes have the enzymes necessary for synthesis of phosphatidylcholine, and incorporation of lipid precursors indicates that synthesis of phosphatidylcholine by Golgi membranes occurs in vivo.
磷脂酰胆碱是极低密度脂蛋白的主要磷脂，它与甘油三酯一起在高尔基池内被包裹。在相同条件下测定，高尔基亚组分的CTP - 磷酸胆碱胞苷转移酶和CDP - 胆碱磷酸转移酶活性高于粗面或滑面微粒体，这表明磷脂酰胆碱的合成可在高尔基膜中发生。与此一致的是，在体内注射[14C]胆碱后，高尔基膜中磷脂酰胆碱的比活性比粗面和滑面微粒体上升得更快。高尔基含量磷脂酰胆碱（非膜组分）的比活性保持较低。高尔基亚组分的S - 腺苷甲硫氨酸磷脂酰乙醇胺甲基转移酶活性也高于粗面或滑面微粒体。在体内注射[3H]甲基标记的甲硫氨酸后，高尔基膜中磷脂酰胆碱的比活性与粗面和滑面微粒体的比活性平行上升。高尔基含量磷脂酰胆碱的比活性上升超过高尔基膜，并呈现出不同的模式，这表明该途径可能选择性地标记作为脂蛋白分泌的磷脂酰胆碱。这些观察结果表明，高尔基膜具有合成磷脂酰胆碱所需的酶，并且脂质前体的掺入表明高尔基膜在体内可合成磷脂酰胆碱。
