植物生長素調控植物生長、發育，包括向性、開花、結果、細胞分裂分化等。存在於植物中最多的生長素為吲哚乙酸 (Indole-3-actic acid，IAA)，當它在頂芽或根部的分生組織合成後，會運送到植物基部被需要的細胞利用，這個過程稱之為生長素的極性運輸 (Polar auxin transport)。細胞膜鑲嵌的生長素轉運蛋白1 (AUX1 transporter) 在極性運輸的時候，可以藉由氫離子梯度差，被動地將細胞外的吲哚乙酸運送到細胞內。485個胺基酸的AUX1預測擁有11個穿膜區域，其大小為56.8 kDa。目前AUX1的生理研究尚稱充裕，惟缺少由結構生物學、生化學的角度剖析吲哚乙酸藉由AUX1進入細胞的途徑與結合的關係。因此，本研究利用大腸桿菌 (Escherichia coli) 異體表現阿拉伯芥 (Arabidopsis thaliana) 的AUX1，檢測AUX1在大腸桿菌中的表現量並分析有AUX1表現的大腸桿菌細胞攝入吲哚乙酸的情形。用有AUX1在大腸桿菌表現的細胞測試不同溫度、作用時間、pH值、及溶液中吲哚乙酸的濃度，與運送到細胞內吲哚乙酸量的關係，並加入化學抑制劑N-乙基馬來醯亞胺 (N-ethylmaleimide) 抑制有AUX1表現的大腸桿菌細胞，證明AUX1可在大腸桿菌系統中表現及分析其功能。此結果可供未來進一步研究AUX1上胺基酸與其交互作用穩定結構間的關係之分析。

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