Combinatorial control of prion protein biogenesis by the signal sequence and transmembrane domain
Combinatorial control of prion protein biogenesis by the signal sequence and transmembrane domain
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DOI：
10.1074/jbc.m101638200
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发表时间：
2001-07-13
影响因子：
4.8
通讯作者：
Hegde, RS
中科院分区：
文献类型：
--
作者：
Kim, SJ;Rahbar, R;Hegde, RS
朊病毒蛋白（PrP）在内质网中以三种拓扑形式合成，（PrP）-Pr-sec完全移位到内质网腔中，而（NPrP）-Pr-tm和（PrP）-Pr-Ctm是相反方向的单跨膜蛋白。在转基因小鼠或人类中（PrP）-Pr-Ctm的产生增加与神经退行性疾病的发展相关。为了研究PrP可以实现三种拓扑结果的机制，我们分析了包含引入PrP的N-末端信号序列或潜在跨膜结构域（TMD）的突变的蛋白质的易位。尽管发现任一结构域中的突变影响PrP拓扑发生，它们以不同的方式实现了这一点。除了其在介导蛋白质靶向中的传统作用之外，发现该信号在确定PrP N末端的取向中发挥令人惊讶的作用。相比之下，TMD被发现影响膜整合。各种信号和TMD双突变体的分析表明，TMD行动的拓扑后果是直接依赖于以前的，信号介导的步骤。总之，这些结果表明，PrP拓扑控制在两个离散的步骤，在其易位，并提供了一个框架，了解这些步骤如何协调行动，以确定最终的拓扑结构实现的PrP。
The prion protein (PrP) is synthesized in three topologic forms at the endoplasmic reticulum, (PrP)-Pr-sec is fully translocated into the endoplasmic reticulum lumen, whereas (NPrP)-Pr-tm and (PrP)-Pr-Ctm are single-spanning membrane proteins of opposite orientation. Increased generation of (PrP)-Pr-Ctm in either transgenic mice or humans is associated with the development of neurodegenerative disease, To study the mechanisms by which PrP can achieve three topologic outcomes, we analyzed the translocation of proteins containing mutations introduced into either the N-terminal signal sequence or potential transmembrane domain (TMD) of PrP, Although mutations in either domain were found to affect PrP topogenesis, they did so in qualitatively different ways. In addition to its traditional role in mediating protein targeting, the signal was found to play a surprising role in determining orientation of the PrP N terminus. By contrast, the TMD was found to influence membrane integration. Analysis of various signal and TMD double mutants demonstrated that the topologic consequence of TMD action was directly dependent on the previous, signal-mediated step. Together, these results reveal that PrP topogenesis is controlled at two discrete steps during its translocation and provide a framework for understanding how these steps act coordinately to determine the final topology achieved by PrP.