Maturation of lipoprotein lipase. Expression of full catalytic activity requires glucose trimming but not translocation to the cis-Golgi compartment.
Maturation of lipoprotein lipase. Expression of full catalytic activity requires glucose trimming but not translocation to the cis-Golgi compartment.
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DOI：
10.1016/s0021-9258(18)42684-1
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发表时间：
1992-03
期刊：
影响因子：
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通讯作者：
O. Ben-Zeev;M. Doolittle;Richard C. Davis;John Elovson;M. Schotz
中科院分区：
文献类型：
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作者：
O. Ben-Zeev;M. Doolittle;Richard C. Davis;John Elovson;M. Schotz
脂蛋白脂酶（LPL）的成熟和它的易位从内质网（ER）到高尔基复合体之间的关系，通过测量脂肪分解活性的条件下，防止运输的酶从ER到高尔基室。布雷菲德菌素A的存在下，一种试剂，抑制运动的蛋白质从ER和导致的高尔基复合体的解体，pro-5中国仓鼠卵巢细胞积累催化活性LPL，而分泌的酶被有效地阻止。LPL保留胞内布雷菲德菌素A治疗拥有的寡糖链，加工成复杂的形式，由高尔基体酶重新分配到ER。在16摄氏度，破坏蛋白质转运到顺式高尔基体的条件下，保留的酶再次保持催化活性，尽管寡糖仍以高甘露糖形式存在。最后，将特异性ER滞留信号KDEL（Lys-Asp-Glu-Leu）连接到LPL的羧基末端也导致完全活性的细胞内滞留酶。还确定了低聚糖加工对获得体外LPL催化活性的重要性。LPL是活跃的，分泌时，修剪的甘露糖残基被抑制脱氧mannojirimycin和添加复合糖时被阻止使用中国仓鼠卵巢突变体（lec 1和lec 2），表明这些处理事件是不必要的功能酶的表达。然而，葡萄糖苷酶抑制剂（栗精胺和N-甲基-脱氧野尻霉素）阻断葡萄糖清除导致LPL比活性和分泌显着减少。因此，葡萄糖修剪LPL寡糖是必不可少的酶的激活，然而，进一步的寡糖加工或易位的酶的顺式高尔基体是不需要在体外脂肪分解活性的充分表达。
The relationship between maturation of lipoprotein lipase (LPL) and its translocation from the endoplasmic reticulum (ER) to the Golgi complex was determined by measuring lipolytic activity under conditions preventing transport of the enzyme from the ER to the Golgi compartment. In the presence of brefeldin A, a reagent that inhibits movement of proteins from the ER and causes the disassembly of the Golgi complex, pro-5 Chinese hamster ovary cells accumulated catalytically active LPL, while secretion of the enzyme was effectively blocked. LPL retained intracellularly by brefeldin A treatment possessed oligosaccharide chains that were processed to the complex form by the Golgi enzymes redistributed into the ER. At 16 degrees C, a condition disrupting protein transport to the cis-Golgi, the retained enzyme again remained catalytically active although the oligosaccharides remained in the high mannose form. Lastly, attachment of the specific ER retention signal KDEL (Lys-Asp-Glu-Leu) to the carboxyl terminus of LPL also resulted in intracellularly retained enzyme that was fully active. The importance of oligosaccharide processing for attainment of LPL catalytic activity in vitro was also determined. LPL was active and secreted when trimming of the mannose residues was inhibited by deoxymannojirimycin and when addition of complex sugars was blocked using Chinese hamster ovary mutants (lec1 and lec2), indicating that these processing events are not necessary for the expression of a functional enzyme. However, blocking glucose removal by glucosidase inhibitors (castanospermine and N-methyl-deoxynojirimycin) resulted in a significant reduction in LPL specific activity and secretion. Thus, glucose trimming of LPL oligosaccharides is essential for enzyme activation; however, further oligosaccharide processing or translocation of the enzyme to the cis-Golgi is not required for full expression of lipolytic activity in vitro.