细胞如何控制离子的进出
文章来源:未知 文章作者:enread 发布时间:2014-10-30 06:29 字体: [ ]  进入论坛
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A common protein plays a different role than previously1 thought in the opening and closing of channels that let ions flow in and out of our cells, researchers at Johns Hopkins report. Those channels are critical to life, as having the right concentrations of sodium2 and calcium3 ions in cells enables healthy brain communication, heart contraction4 and many other processes. The new study reveals that a form of calmodulin long thought to be dormant5 actually opens these channels wide. The finding is likely to bring new insight into disorders6 caused by faulty control of these channels, such as cardiac arrhythmias, epilepsy and Parkinson's disease, the researchers say. A report on the finding appears in the Oct. 23 issue of the journal Cell.
 
In the current model, explains David Yue, M.D., Ph.D. , a professor of biomedical engineering and neuroscience at the Johns Hopkins University School of Medicine, calmodulin can do little until it binds8 to calcium, which changes its shape and snaps it into action. The activated9 calmodulin can then bind7 to a specialized10 control lever inside calcium and sodium channels, which closes the channels.
 
The new study revises this viewpoint by devising ways to deliver surges of calcium-free calmodulin to channels. In so doing, "it can be seen that calcium-free calmodulin is in no way dormant, but instead markedly boosts the opening of calcium and sodium channels to begin with," Yue says. When calcium binds to the "resident" calcium-free calmodulin on channels, this initial enhancement dissipates. "The two forms of calmodulin are both powerful, each imposing11 opposing actions that together maintain exquisite12 control, akin13 to the 'yin-yang' balance in Chinese philosophy," Yue says. "This insight into how the calmodulin-controlled lever works could ultimately help in finding treatments for a plethora14 of conditions that stem from faulty ion channels."


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1 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
2 sodium Hrpyc     
n.(化)钠
参考例句:
  • Out over the town the sodium lights were lit.在外面,全城的钠光灯都亮了。
  • Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。
3 calcium sNdzY     
n.钙(化学符号Ca)
参考例句:
  • We need calcium to make bones.我们需要钙来壮骨。
  • Calcium is found most abundantly in milk.奶含钙最丰富。
4 contraction sn6yO     
n.缩略词,缩写式,害病
参考例句:
  • The contraction of this muscle raises the lower arm.肌肉的收缩使前臂抬起。
  • The forces of expansion are balanced by forces of contraction.扩张力和收缩力相互平衡。
5 dormant d8uyk     
adj.暂停活动的;休眠的;潜伏的
参考例句:
  • Many animals are in a dormant state during winter.在冬天许多动物都处于睡眠状态。
  • This dormant volcano suddenly fired up.这座休眠火山突然爆发了。
6 disorders 6e49dcafe3638183c823d3aa5b12b010     
n.混乱( disorder的名词复数 );凌乱;骚乱;(身心、机能)失调
参考例句:
  • Reports of anorexia and other eating disorders are on the increase. 据报告,厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
  • The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》
7 bind Vt8zi     
vt.捆,包扎;装订;约束;使凝固;vi.变硬
参考例句:
  • I will let the waiter bind up the parcel for you.我让服务生帮你把包裹包起来。
  • He wants a shirt that does not bind him.他要一件不使他觉得过紧的衬衫。
8 binds c1d4f6440575ef07da0adc7e8adbb66c     
v.约束( bind的第三人称单数 );装订;捆绑;(用长布条)缠绕
参考例句:
  • Frost binds the soil. 霜使土壤凝结。 来自《简明英汉词典》
  • Stones and cement binds strongly. 石头和水泥凝固得很牢。 来自《简明英汉词典》
9 activated c3905c37f4127686d512a7665206852e     
adj. 激活的 动词activate的过去式和过去分词
参考例句:
  • The canister is filled with activated charcoal.蒸气回收罐中充满了活性炭。
10 specialized Chuzwe     
adj.专门的,专业化的
参考例句:
  • There are many specialized agencies in the United Nations.联合国有许多专门机构。
  • These tools are very specialized.这些是专用工具。
11 imposing 8q9zcB     
adj.使人难忘的,壮丽的,堂皇的,雄伟的
参考例句:
  • The fortress is an imposing building.这座城堡是一座宏伟的建筑。
  • He has lost his imposing appearance.他已失去堂堂仪表。
12 exquisite zhez1     
adj.精美的;敏锐的;剧烈的,感觉强烈的
参考例句:
  • I was admiring the exquisite workmanship in the mosaic.我当时正在欣赏镶嵌画的精致做工。
  • I still remember the exquisite pleasure I experienced in Bali.我依然记得在巴厘岛所经历的那种剧烈的快感。
13 akin uxbz2     
adj.同族的,类似的
参考例句:
  • She painted flowers and birds pictures akin to those of earlier feminine painters.她画一些同早期女画家类似的花鸟画。
  • Listening to his life story is akin to reading a good adventure novel.听他的人生故事犹如阅读一本精彩的冒险小说。
14 plethora 02czH     
n.过量,过剩
参考例句:
  • Java comes with a plethora of ready-made types.Java配套提供了数量众多的现成类型。
  • A plethora of new operators will be allowed to enter the market.大批新的运营商将获准进入该市场。
TAG标签: cells calcium channels
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