蛋白質移位至內質網膜的反應機制之研究

CMUR > College of Medicine > Graduate Institute of Medical Science > Research reports > Item 310903500/25287

Please use this identifier to cite or link to this item: http://ir.cmu.edu.tw/ir/handle/310903500/25287

Title:	蛋白質移位至內質網膜的反應機制之研究 A Study on Protein Translocation at the Endoplasmic Reticulum Membrane
Authors:	陳瑞彰
Contributors:	中國醫藥大學醫學研究所
Keywords:	蛋白移位;信號序列;信號認定分子;螢光共振能量轉移;Protein translocation;Signal sequence;Signal recognition particle;FRET
Date:	2006-07
Issue Date:	2010-07-21 16:41:13 (UTC+8)
Abstract:	最近在蛋白質由細胞質移位到內質網膜上的分子過程的研究已經有相當的進展﹐但是由信號序列所引導移位到內質網膜上的分子機制並沒有被完全瞭解﹐部分是由於與糖質體結合的新生蛋白鍊的巨大與組成之複雜性﹐而一部分是因為移位時各個過程須經歷多種不同的環境﹐因此造成在移位過程中對信號序列的結構之研究的困難度。我們之前已利用將螢光或光反應探針放在剛被糖質體所製造出來的新生蛋白鍊中的信號序列來研究新生蛋白移位的反應機制﹐並將完整而且具有功能的移位複合體接上探針加以純化來中做研究﹐以此方法我們已經解決了新生蛋白要從細胞質移位至內質網膜這個過程一些具爭議性的重要問題。現在我們提出的研究計畫要再度利用這個螢光技術以及螢光共振能量轉移的技術來研究有關由信號序列所引導的蛋白移位之下列幾個問題﹕(一) 連接糖質體的信號序列的結構為何? 它的結構在糖質體的通道裡與在暴露在糖質體外時的結構有不同嗎? 這樣的結構若與信號認定分子結合時會改變嗎? 而它進入內質網膜時其結構又為何?(二) 信號序列與信號認定分子結合後其相關幾何位置為何? 信號序列裡的厭水區段會被信號認定分子完全包在裡面嗎? Considerable progress has been made recently in our understanding of proteintranslocation into endoplasmic reticulum. However, the molecular mechanisms that accomplish signal sequence dependent protein translocation across andintegration into the endoplasmic reticulum (ER) membrane has not been clarified,partly because of the huge and complicated composition of the ribosome-associated nascent chain complex and partly because each process must be involved in several different environments. Very little is now known about the environment and conformation of the signal sequence as it is synthesized by the ribosome, associated with the signal recognition particle, and incorporated into the ER membrane. We have previously investigated protein trafficking from the point of view of the signal sequence by incorporating fluorescent dyes into the ribosome-associated nascent chain as it is being synthesized by the ribosome. By examining functional, fully assembled, and intact translocation complexes with probes in the signal sequence, we have elucidated several important molecular mechanistic aspects of these processes. We now propose a project to extend our unique fluorescence and fluorescence resonance energy transfer (FRET) investigation of protein translocation by addressing questions that include: 1. What is the conformation of the signal sequence of a nascent peptide? Are they different in the ribosomal tunnel and exposed to the cytosol? Is the conformation altered as it associated with the signal recognition particle? Does it become alpha helix like conformation when it inserts into ER membrane? 2. What is the topology the signal sequence when it associates with the signal recognition particle? Is the hydrophobic segment of the signal sequence completely buried into M-domain of SRP54 proteins as it binds to SRP?
Appears in Collections:	[Graduate Institute of Medical Science] Research reports

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