Multiple nuclear localization sequences allow modulation of 5-lipoxygenase nuclear import
Multiple nuclear localization sequences allow modulation of 5-lipoxygenase nuclear import
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DOI：
10.1111/j.1600-0854.2004.00227.x
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发表时间：
2004-11-01
期刊：
影响因子：
4.5
通讯作者：
Brock, TG
中科院分区：
文献类型：
--
作者：
Luo, M;Pang, CWM;Brock, TG
蛋白质的核输入通常需要核定位序列（NLS）的存在。有些蛋白质有一个以上的NLS，但具有多个NLS的意义尚不清楚。酶5-脂氧合酶（5-LO）具有三个NLSs，与经典SV40大T抗原NLS的紧密基残基簇不同，它们含有分散的基残基。当附着绿色荧光蛋白（GFP）时，个体5-LO NLS在定量和统计上的重要性低于SV40 NLS。合并后的5-LO NLS生产的核进口量与SV40 NLS相当。正如预期的那样，GFP/NLS蛋白在所有细胞中表现出相对均匀的输入。然而，GFP与5-LO蛋白的融合蛋白被修饰为只含有一个功能性NLS，产生了一些有输入的细胞和一些没有输入的细胞。含有两个功能性NLSs的GFP/5-LO融合蛋白产生四个可识别的核输入水平。对表达完整GFP/5-LO蛋白的细胞群体进行定量和视觉分析，发现有三个完整的NLSs，表明有五个水平的核输入。这表明5-LO在机体正常细胞中的亚细胞分布可能有很大差异。与此一致的是，肺切片的免疫组织化学染色发现单个巨噬细胞原位显示细胞特异性的5-LO输入水平。由于已知核积累会影响5-LO活性，多个NLSs可以通过控制进口来分级调节活性。其他蛋白质上的多个NLSs同样可以通过调节进口水平来精细控制蛋白质的作用。
The nuclear import of proteins typically requires the presence of a nuclear localization sequence (NLS). Some proteins have more than one NLS, but the significance of having multiple NLSs is unclear. The enzyme 5-lipoxygenase (5-LO) has three NLSs that, unlike the tight cluster of basic residues of the classical SV40 large T antigen NLS, contain dispersed basic residues. When attached to green fluorescent protein (GFP), individual 5-LO NLSs caused quantitatively and statistically less import than the SV40 NLS. Combined 5-LO NLSs produced nuclear import that was comparable to that of the SV40 NLS. As expected, GFP/NLS proteins displayed relatively uniform import in all cells. However, a fusion protein of GFP plus the 5-LO protein, modified to contain only one functional NLS, produced some cells with import and some cells without import. A GFP/5-LO fusion protein containing two functional NLSs produced four identifiable levels of nuclear import. Quantitative and visual analysis of a population of cells expressing the intact GFP/5-LO protein, with three intact NLSs, indicated five levels of nuclear import. This suggested that the subcellular distribution of 5-LO may vary widely in normal cells of the body. Consistent with this, immunohistochemical staining of lung sections found that individual macrophages, in situ, displayed cell-specific levels of import of 5-LO. Since nuclear accumulation is known to affect 5-LO activity, multiple NLSs may allow graded regulation of activity via controlled import. Multiple NLSs on other proteins may likewise allow fine control of protein action through modulation of the level of import.