SNAP-tag技術在STED超高分辨率顯微成像中的應用
近十年中，顯微成像技術得到了飛躍的發展，填補光學顯微鏡（~200 nm）到電子顯微鏡（~0.1 nm）分辨率缺口，打破光學衍射極限的超高分辨率顯微鏡也越來越趨于成熟化。其中，德國馬普研究所的Stefan Hell教授憑借其研發的受激發射損耗（Stimulatedemission depletion，STED）技術榮獲2014年的諾貝爾化學獎。STED超高分辨率顯微鏡是架構在共聚焦顯微鏡上，因此其成像速度非常快，可以廣泛的應用于活細胞的超高分辨率成像。除了傳統的YFP等熒光蛋白可以用于STED活細胞超高分辨率成像，SNAP-tag和CLIP-tag可以非常簡便的的將AlexaFluo等有機染料引入活細胞，實現活細胞中多色超高分辨率成像。有機染料具有更好的光穩定性，光譜的選擇也更加靈活，配合SNAP-tag和CLIP-tag標記的特異性和穩定性，可以更優秀的服務于長時間的活細胞超高分辨率顯微成像。Joerg B等科學家用SNAP-tag/BG-94和CLIP-tag/BC-647分別標記了表皮生長因子受體（EGFR）和表皮生長因子（EGF）（圖2），利用STED超高分辨率顯微鏡解析了兩者在活細胞中的相互作用（圖3）[12]。
圖2.SNAP-tag/BG-494和CLIP-tag/BC-647N分別標記EGFR和EGF的示意圖。原則上EGFR和EGF結合后會形成同源二聚體，在這里考慮到示意圖的簡潔清晰性，EGFR仍然以單體的形式表示。
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