Caspase-3细胞定位信号的检测与分析

Identification and Analysis of Subcellular Localization Signal of Caspase-3

Caspase-3是调节细胞凋亡的关键蛋白质.凋亡过程中,胞质定位的caspase-3被酶解激活,进入细胞核中执行功能.这一定位变化的分子机制至今仍不清楚.分析caspase-3分子中所含的细胞定位信号,可以为深入了解其移位机制提供重要的线索.构建一系列含caspase-3不同区段的截短突变体,与GFP融合表达,观察它们在细胞中的定位,以鉴定caspase-3分子中所含的核输出信号（nuclear export signal,NES）和核定位信号NLS（nuclear localization signal,NLS）.结果发现,caspase-3分子中不存在明显的NLS,但存在一个明显的NES,该NES定位在caspase-3小亚基的C端,包括220-245位氨基酸残基.

Caspase-3 is a key mediator of apoptosis.During apoptosis,caspase-3 is cleaved and activated by the protease,and enters into the nucleus,resulting in biochemical and morphological changes in apoptosis.However,the molecular mechanism of nucleus-entering of active caspase-3 is still unknown.Identifying the subcellular localization of caspase-3 molecule is important for understanding the process.In this study,we constructed various truncated caspase-3 mutant constructs that were fused with GFP,observed the cellular localization of these mutant proteins,and determined the subcellular localization of caspase-3 molecule.The results show that caspase-3 lacks obvious nuclear localization signal（NLS）,but bears an obvious nuclear export signal（NES）,which is located at the C-terminus of its small subunit including residues 220～245.