BEX2(Brain expressed X-linked protein 2)分子量约为13 kDa, 高表达于人的脑和睾丸中。据报道, 该蛋白在胚胎发育中表达量变化巨大, 提示该蛋白可能在胚胎发育中具有重要作用, 但迄今为止, 其功能知之甚少。文章应用酵母双杂交系统, 以BEX2为“诱饵”蛋白, 筛选发现INI1/hSNF5是BEX2的一个结合蛋白。INI1/hSNF5是SWI/SNF染色质重塑复合体的核心组分, 是“表观遗传”分子机制中的重要成员。文章通过体外GST Pull-down实验验证, BEX2与INI1/hSNF5之间的相互作是直接并且特异的。通过进一步的缺失突变分析, 表明INI1/hSNF5的两个保守的反向重复序列是BEX2的结合区域。该区域是SNF5与多种蛋白相互作用的结构平台。亚细胞定位分析显示BEX2与INI1/hSNF5都主要集中分布于细胞核, 这表明二者之间的相互作用可能参与基因表达调控的过程。文章进一步对此相互作用的功能进行了探讨, 发现BEX2 通过与INI1/hSNF5的相互作用从而影响细胞周期。
BEX2 (Brain expressed X-linked protein 2), a 13 kDa protein, is highly expressed in brain and testis. It is reported that the protein expression of BEX2 dramatically alters during the embryo development, but little is known about its function. By means of yeast two-hybrid screening, we isolated that INI1/hSNF5 was a binding partner for BEX2, a key component of SWI/SNF chromosome remolding complex. GST Pull-down experiment interaction is physical and specific. Further analysis using truncated mutations demonstrated that the two partner for BEX2, a key component of SWI/SNF chromosome remolding complex. GST Pull-down experiment confirmed that BEX2 can interact with INI1/hSNF5 directly and specifically. Truncated mutations analysis further demonstrated that the two conserved reverse repeats sequences within INI1/hSNF5 were necessary for the interaction. Sub-cellular localization showed that both BEX2 and INI1/hSNF5 mainly localized in cell nucleus, which indicated that the interaction may be involved in the regulation of gene expression. Our experiments also showed that co-overexpressing of the two proteins affected cell cycle by increasing the cells in S phase, indicating that BEX2 could regulate cell cycle by interacting with INI1/hSNF5.
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