Targeting and processing of glycophorins in murine erythroleukemia cells: use of brefeldin A as a perturbant of intracellular traffic.
Targeting and processing of glycophorins in murine erythroleukemia cells: use of brefeldin A as a perturbant of intracellular traffic.
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DOI：
10.1073/pnas.86.18.6992
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发表时间：
1989-09
影响因子：
11.1
通讯作者：
Jeffrey B. Ulmer;G. Palade
中科院分区：
文献类型：
--
作者：
Jeffrey B. Ulmer;G. Palade
我们以前表明，血型糖蛋白在病毒转化的小鼠红白血病细胞中表达;我们检测到四个血型糖蛋白前体（比正常成红细胞多两个），并发现其中两个不能易位或不能有效地易位穿过内质网（ER）膜。通过使用药物布雷菲德菌素A来阻断蛋白质从ER到高尔基复合体的细胞内转运，易位的前体被证明在ER中积累，而未易位的形式被迅速降解，细胞内半衰期约为20分钟。布雷菲德菌素A不抑制前体脂肪酰化的合成，但大大延迟了它们获得O-连接的寡糖，这表明鼠血型糖蛋白在ER中是脂肪酰化的，在高尔基复合体中是O-糖基化的。即使在布雷菲德菌素A中6小时后，血型糖蛋白也仅部分糖基化，导致明显唾液酸化但表观分子量低于成熟血型糖蛋白的糖蛋白积累。完全血型糖蛋白加工仅在移除药物后恢复。在小鼠红白血病细胞中，布雷菲德菌素A引起整个高尔基复合体的快速和广泛的解体，伴随着在与ER过渡元素密切相关的ER的一部分中膜的积累。这些发现扩展了最近发表的结果[Lippincott-Schwartz，J.，元湖，澳-地C.的方法，博尼法西诺<英>来华传教士。& Klausner，R. D.（1989）Cell 56，801-813]，并表明布雷菲德菌素A诱导从整个高尔基复合体到ER的净膜流动。
We previously showed that glycophorins are expressed in virus-transformed, murine erythroleukemia cells; we detected four glycophorin precursors (two more than in normal erythroblasts) and found that two of them are not translocated or are inefficiently translocated across the endoplasmic reticulum (ER) membrane. By using the drug brefeldin A to block intracellular transport of proteins from the ER to the Golgi complex, the translocated precursors were shown to accumulate in the ER, while the untranslocated forms were rapidly degraded with an intracellular half-life of approximately 20 min. Brefeldin A did not inhibit the synthesis of fatty acylation of the precursors but substantially delayed their acquisition of O-linked oligosaccharides, which indicates that murine glycophorins are fatty acylated in the ER and O-glycosylated in the Golgi complex. Even after 6 hr in brefeldin A, glycophorins were only partially glycosylated, resulting in the accumulation of glycoproteins apparently sialylated but lower in apparent molecular mass than mature glycophorins. Complete glycophorin processing resumed only after removal of the drug. In murine erythroleukemia cells, brefeldin A caused a rapid and extensive disorganization of the entire Golgi complex accompanied by the accumulation of membranes in a part of the ER closely associated with ER transitional elements. These findings extend recently published results [Lippincott-Schwartz, J., Yuan, L. C., Bonifacino, J. S. & Klausner, R. D. (1989) Cell 56, 801-813] and suggest that brefeldin A induces net membrane flow from the entire Golgi complex to the ER.