Topology of the C-terminal fragment of human presenilin 1.
Topology of the C-terminal fragment of human presenilin 1.
复制标题
人早老素 1 C 末端片段的拓扑结构。
DOI：
10.1021/bi0509494
复制
发表时间：
2005
期刊：
影响因子：
2.9
通讯作者：
Turner,RJames
中科院分区：
文献类型：
--
作者：
Oh,YoungS;Turner,RJames
人类早老素1（PS1）的突变与早发性家族性阿尔茨海默病有遗传联系。PS1含有10个疏水区（HR），其长度足以成为α-螺旋跨膜片段。大多数以前的拓扑学研究都认为PS1的N-末端是胞质的，HRs 1 - 6跨越膜，但HR 7没有。然而，HRs 8和9是否是跨膜片段仍然存在争议。在这里，我们研究的拓扑结构和生物起源的PS1使用报告基因融合的方法，其中部分的PS1序列含有可能的跨膜段融合的报告序列的上游或下游，其易位到内质网可以通过其糖基化监测。我们提供了强有力的证据，在全长PS1的半胱氨酸可及性研究的支持下，HR 8和9确实是跨膜和HR 8到膜的整合是依赖于HR 9的存在。我们还解释了我们的结果如何调和以前显然不同的结论，关于HR 8和9的拓扑结构。
Mutations of human presenilin 1 (PS1) have been genetically linked to early-onset familial Alzheimer's disease. PS1 contains 10 hydrophobic regions (HRs) sufficiently long to be α-helical membrane spanning segments. Most previous topology studies agree that the N-terminus of PS1 is cytosolic and HRs 1−6 span the membrane but HR 7 does not. However, whether HRs 8 and 9 are membrane spanning segments remains controversial. Here we study the topology and biogenesis of this region of PS1 using a reporter gene fusion approach, where portions of the PS1 sequence containing possible membrane spanning segments were fused up- or downstream of a reporter sequence whose translocation into the endoplasmic reticulum could be monitored via its glycosylation. We provide strong evidence, supported by cysteine accessibility studies in full-length PS1, that HRs 8 and 9 are indeed membrane spanning and that the integration of HR 8 into the membrane is dependent on the presence of HR 9. We also explain how our results reconcile previous apparently divergent conclusions regarding the topology of HRs 8 and 9.