臺灣博碩士論文加值系統

為了了解細胞核運送訊息序列(Nuclear Localization Signal; NLS)以及細胞核仁運送訊息序列(Nucleolar Localization Signal; NoLS)對蛋白質分子進入細胞核及細胞核仁的影響，我們選擇核醣體蛋白質L7作為進入細胞核的實驗模式。已知L7氨基端第1-54個氨基酸本身即具有進入細胞核的能力，在此氨基端中，經序列比較發現它含有四個類似SV 40之細胞核運送訊息序列的鹼性氨基酸群(basic amino acid cluster)，分別命名為N1、N2、N3和N4，因此本研究以三倍綠色螢光蛋白((EGPF)3)做為報導蛋白，建構不同數目鹼性氨基酸群的L7變異蛋白質，觀察此四個鹼性氨基酸群是否具有細胞核以及細胞核仁運送訊息序列的能力，發現N2、N3和N4均具有細胞核運送序列之能力，但是在效率上有所差異；而N1、N2、N3和N4必須同時存在，才具有細胞核仁運送訊息序列的能力。

To understand the effect of the nuclear localization signal (NLS) and the nucleolar localization signal (NoLS) within protein structure to the nuclear trafficking, the NH2-terminal region of human ribosomal protein L7 was chosen as the study model, because the NH2 terminus of L7 is capable of entering the nucleus and the nucleolus. The NH2 terminus can be divided into four motifs, N1, N2, N3 and N4, according to the knowledge of the SV 40 T antigen NLS. Each motif was separately fused to the NH2 terminus of 3 copies of enhanced green fluorescence protein ((EGFP)3) to investigate their NLS ability. These constructs were transfected into HeLa cell. The localization of transiently expressed proteins in cells were observed using confocal microscope. Among these motifs, N2, N3 and N4, but not N1, function as NLSs, however, none of them can make (EGFP)3 entering the nucleoli. By making combinations of different motifs with (EGFP)3, the nucleolus entry was examined. The results found that (EGFP)3 get into the nucleolus only when the entire sequence of N1, N2, N3 and N4 exist.

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