OCH1 ENCODES A NOVEL MEMBRANE-BOUND MANNOSYLTRANSFERASE - OUTER CHAIN ELONGATION OF ASPARAGINE-LINKED OLIGOSACCHARIDES
OCH1 ENCODES A NOVEL MEMBRANE-BOUND MANNOSYLTRANSFERASE - OUTER CHAIN ELONGATION OF ASPARAGINE-LINKED OLIGOSACCHARIDES
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DOI：
10.1002/j.1460-2075.1992.tb05316.x
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发表时间：
1992-07-01
期刊：
影响因子：
11.4
通讯作者：
JIGAMI, Y
中科院分区：
文献类型：
--
作者：
NAKAYAMA, K;NAGASU, T;JIGAMI, Y
酿酒酵母och1突变体在非允许温度下甘露糖外链伸长不足。我们通过对温度敏感表型的互补克隆了OCH1基因用于生长。酵母染色体上的OCH1基因整合体可以对其ts表型进行互补，并显示出与OCH1突变基因相同的定位，表明克隆的基因是真正的突变基因。OCH1基因干扰物不是致命的，但对细胞生长有影响，并且缺乏甘露糖外链。OCH1基因序列预测一个55 kDa的蛋白质由480个氨基酸组成。它含有四个潜在的天冬酰胺连接（n -连接）糖基化位点和靠近n端的单个跨膜区域。体外翻译/易位分析显示，OCH1蛋白的大c端位于微粒体膜的管腔侧，并进行了一些糖修饰，表明其为II型膜拓扑结构。在酵母膜组分中检测到OCH1蛋白为58-66 kDa的四种形式，其大小与内质网（ER）中形成的含有四条n链糖链的糖蛋白的长度几乎相同或略大于内核（Man8GlcNAc2）。最后，我们发现OCH1基因编码了一种新的甘露糖基转移酶，它能特异性地将[C-14]甘露糖转移到独特的受体上，即在OCH1干扰物中积累的细胞壁甘露糖的核状低聚糖。
The Saccharomyces cerevisiae och1 mutant shows a deficiency in the mannose outer chain elongation at the non-permissive temperature. We have cloned the OCH1 gene by complementation of temperature sensitive (ts) phenotype for growth. The integrant of OCH1 gene in the yeast chromosome can complement the ts phenotype and shows the same mapping position as that of the och1 mutation, indicating that the cloned gene is the true gene for mutation. The OCH1 gene disruptant is not lethal but ts for cell growth, and lacks mannose outer chains. The OCH1 gene sequence predicts a 55 kDa protein consisting of 480 amino acids. It contains four potential asparagine-linked (N-linked) glycosylation sites and a single transmembrane region near the N-terminus. In vitro translation/translocation analysis revealed that the large C-terminal region of the OCH1 protein is located at the lumenal side of microsomal membranes with some sugar modification, indicating a type II membrane topology. The OCH1 protein was detected in yeast membrane fractions as four forms of 58-66 kDa, which correspond to the size of a glycoprotein containing four N-linked sugar chains the length of which is almost the same or slightly larger than the inner core (Man8GlcNAc2) formed in the endoplasmic reticulum (ER). Finally, the OCH1 gene was found to encode a novel mannosyltransferase which specifically transfers [C-14]mannose to the unique acceptor, the core-like oligosaccharide of cell wall mannan accumulated in the och1 disruptant.