加拿大和美國(guó)科學(xué)家聯(lián)合研究小組開(kāi)發(fā)出一種應(yīng)用熒光光譜技術(shù)觀察研究單個(gè)膜蛋白運(yùn)動(dòng)的新方法。膜蛋白的主要功能是控制細(xì)胞與其周邊環(huán)境的離子交換,。專家認(rèn)為,，該項(xiàng)研究成果有助于人們?cè)鰪?qiáng)對(duì)離子通道的認(rèn)識(shí)和了解,。相關(guān)研究文章發(fā)表在最新出版的《美國(guó)國(guó)家科學(xué)院院報(bào)》上。
離子通道類(lèi)似于一臺(tái)小型納米機(jī)器或納米閥門(mén),，如果這些微小閥門(mén)運(yùn)轉(zhuǎn)失靈,，將引發(fā)人體肌肉、中樞神經(jīng)系統(tǒng)和心臟等發(fā)生各種遺傳疾病,。
與照相機(jī)的光圈原理相似,，這些膜蛋白通過(guò)開(kāi)啟和關(guān)閉動(dòng)作來(lái)控制細(xì)胞與其周邊環(huán)境的離子交換運(yùn)動(dòng)，這種離子交換運(yùn)動(dòng)促成了沿著我們神經(jīng)細(xì)胞的電信號(hào)的傳輸,。這些細(xì)微閥門(mén)的尺寸大約是人眼瞳孔大小的百萬(wàn)分之一,。加美科學(xué)家所采用的新技術(shù)可測(cè)量到單離子通道，并可研究離子通道內(nèi)部不同部分之間如何進(jìn)行信息溝通,。
由加拿大蒙特利爾大學(xué)物理系教授里卡德·布朗克牽頭的聯(lián)合小組對(duì)基于4個(gè)同樣的亞單元建立的鉀離子通道進(jìn)行了研究,，這種鉀離子通道形成了可以穿過(guò)膜的微細(xì)小孔，小孔能夠打開(kāi)和關(guān)閉以開(kāi)通或阻斷離子傳導(dǎo),。
科學(xué)家使用新開(kāi)發(fā)出的熒光光譜技術(shù)，區(qū)分出4個(gè)亞單元,，首次實(shí)現(xiàn)了對(duì)4個(gè)亞單元的運(yùn)動(dòng)分別進(jìn)行跟蹤研究,。他們發(fā)現(xiàn)，4個(gè)亞單元分子是協(xié)同發(fā)揮作用的,，從而解釋了為何在電生理學(xué)實(shí)驗(yàn)中沒(méi)有在電流中發(fā)現(xiàn)中間級(jí),。該項(xiàng)研究成果解決了在該領(lǐng)域存在的長(zhǎng)期爭(zhēng)論：一個(gè)鉀離子的4個(gè)亞單元究竟是各自獨(dú)立發(fā)揮作用還是協(xié)同發(fā)揮作用。
布朗克博士表示,，該項(xiàng)發(fā)現(xiàn)有助于增強(qiáng)人們對(duì)離子通道的認(rèn)識(shí)和了解,。其重要性在于，膜蛋白在人體中發(fā)揮著重要的作用,，而且其基因突變會(huì)引發(fā)許多嚴(yán)重的遺傳疾病,，也因此它們是重要的藥物標(biāo)靶。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS December 11, 2008, doi: 10.1073/pnas.0807056106
Fluorescence detection of the movement of single KcsA subunits reveals cooperativity
Rikard Bluncka,1, Hugo McGuirea, H. Clark Hydeb, and Francisco Bezanillab
aDépartement de Physique and GéPROM, Université de Montréal, Montréal, QC, Canada H3C 3J7; and
bDepartment of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
The prokaryotic KcsA channel is gated at the helical bundle crossing by intracellular protons and inactivates at the extracellular selectivity filter. The C-terminal transmembrane helix has to undergo a conformational change for potassium ions to access the central cavity. Whereas a partial opening of the tetrameric channel is suggested to be responsible for subconductance levels of ion channels, including KcsA, a cooperative opening of the 4 subunits is postulated as the final opening step. In this study, we used single-channel fluorescence spectroscopy of KcsA to directly observe the movement of each subunit and the temporal correlation between subunits. Purified KcsA channels labeled at the C terminus near the bundle crossing have been inserted into supported lipid bilayer, and the fluorescence traces analyzed by means of a cooperative or independent Markov model. The analysis revealed that the 4 subunits do not move fully independently but instead showed a certain degree of cooperativity. However, the 4 subunits do not simply open in 1 concerted step.
