【摘 要】
:
天冬酰胺糖基化(Asparagine-linked glycosylation)是真核细胞中一种重要的蛋白翻译后修饰过程。随着在内质网膜上合成的寡糖结构被转移到新生肽链的糖基化位点(NXS/T,N为天冬酰胺,X为除脯氨酸之外任意氨基酸,S/T为丝氨酸/苏氨酸)的天冬酰胺残基上,糖原(N-glycan)会被快速剪切形成特殊的带有单葡萄糖的结构参与分子伴侣对多肽的识别及折叠过程。另一方面,不能形成正确
【机 构】
:
南京大学医药生物技术国家重点实验室,生命科学学院南京210023
【出 处】
:
江苏省植物生理学会2016年学术年会
论文部分内容阅读
天冬酰胺糖基化(Asparagine-linked glycosylation)是真核细胞中一种重要的蛋白翻译后修饰过程。随着在内质网膜上合成的寡糖结构被转移到新生肽链的糖基化位点(NXS/T,N为天冬酰胺,X为除脯氨酸之外任意氨基酸,S/T为丝氨酸/苏氨酸)的天冬酰胺残基上,糖原(N-glycan)会被快速剪切形成特殊的带有单葡萄糖的结构参与分子伴侣对多肽的识别及折叠过程。另一方面,不能形成正确构象的多肽其携带的N-glycan在糖苷酶的作用下被剪切,暴露出一个α1,6键连接的甘露糖结构,成为引导蛋白进入降解途径的信号。因此,N-glycan的正确剪切对维持内质网内蛋白合成内环境的稳定至关重要。在动植物细胞中,随着蛋白由内质网分泌进入高尔基体,蛋白所携带的N-glycan会被继续剪切、加工形成复杂糖原。尽管复杂糖原修饰过程出现紊乱会引起人类Ⅱ型CDG疾病以及植物对盐敏感的根表型,但目前有关N-glycan需要进行复杂修饰的生物学意义还所知甚少。本研究中,我们通过比较影响N-glycan复杂化的两种不同突变体对外界非生物胁迫的响应,发现高尔基体内的N-glycan剪切紊乱会引起植株对盐胁迫更为敏感的表型。通过遗传杂交实验,我们发现高尔基体内的N-glycan的剪切是一个重要的调节信号,调节底物分泌蛋白顺利被运输到最终的功能位点。以上研究结果说明了细胞内存在以N-glycan不同结构作为调节信号精密调节分泌蛋白折叠和分泌的分子机制。
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