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信号肽位于分泌蛋白的氨基端,一般由15~30个氨基酸组成.图一为信号肽序列合成后,被信号识别颗粒(SRP)所识别,蛋白质合成暂停或减缓.SRP将核糖体携带至内质网上,蛋白质合成重新开始.在信号肽的引导下,新合成的蛋白质进入内质网腔.图二为图l的部分放大示意图.请分析回答下列问题:

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    It started as a special day for Wesley Autrey, a 50-year-old construction worker in New York City. It was about 12:45 P.M., and he was waiting on a subway platform (月台) to take his daughters home before he went to work. He suddenly noticed a man nearby have convulsions (抽搐) and fall down suddenly. Mr. Autrey and two women went to help the stranger. The man, Cameron Hollopeter, managed to get to his feet, but then stumbled (绊倒) at the edge of the platform and fell onto the subway tracks. Mr. Autrey looked up and saw the lights of the subway train coming near through the tunnel.

    Mr. Autrey jumped onto the track immediately. He realized that he didn't have time to get Mr. Hollopeter and himself back up on the platform before the train arrived, so he lay on top of the man and pressed down as hard as he could. Although the driver tried to stop the train before it reached them, he couldn't. Five cars passed over them before the train finally stopped. The cars had passed only inches from his head.

    New York loves a hero. Mr. Autrey became an overnight hero and was named the “Subway Superman”. New York City Mayor Michael Bloomberg gave him the Bronze Medallion, the city's highest honor. He was asked to appear on several TV talk shows. He was also rewarded with money and gifts, such as $10,000 from Donald Trump, a $5,000 gift card from the Gap clothing store, a new Jeep, and Beyonce concert tickets.

    How did Autrey react (反应) to all this? He said, “I don't feel like I did anything great; I just saw someone who needed help. I did what I felt was right”.