Yamada Kazuya, Kawata Hiroko, Shou Zhangfei, Hirano Satoko, Mizutani Tetsuya, Yazawa Takashi, Sekiguchi Toshio, Yoshino Miki, Kajitani Takashi, Miyamoto Kaoru
Department of Biochemistry, Fukui Medical University, and Japan and CREST, Japan Science and Technology, Fukui 910-1193, Japan.
Biochem J. 2003 Jul 1;373(Pt 1):167-78. doi: 10.1042/BJ20021866.
Human zinc-fingers and homeoboxes (ZHX) 1, a transcriptional repressor, was originally cloned as an interacting protein with the activation domain of the A subunit of nuclear factor-Y (NF-YA). As the first step in investigating the mechanism by which ZHX1 acts as a transcriptional repressor, we conducted a search of ZHX1-interacting proteins using a yeast two-hybrid system. Nuclear proteins such as ZHX1, transcriptional co-factors and DNA-binding proteins, zyxin, androgen-induced aldose reductase and eleven-nineteen lysine-rich leukaemia gene, as well as some unknown proteins, were cloned. Molecular cloning and determination of the nucleotide sequence of the full-length cDNA encoding a novel protein revealed that it consists of 956 amino acid residues and contains two zinc-finger (Znf) motifs and five homeodomains (HDs) as well as ZHX1. We concluded that the protein forms the ZHX family with ZHX1 and denoted it ZHX3. ZHX3 not only dimerizes with both ZHX1 and ZHX3, but also interacts with the activation domain of the NF-YA. Further analysis revealed that ZHX3 is a ubiquitous transcriptional repressor that is localized in nuclei and functions as a dimer. Lastly, the dimerization domain, the interaction domain with NF-YA, and the repressor domain are mapped to a region including the HD1 region, and two nuclear localization signals are mapped to the N-terminal through Znf1 and the HD2 region, respectively.
人类锌指和同源框（ZHX）1是一种转录抑制因子，最初作为与核因子-Y（NF-YA）A亚基激活域相互作用的蛋白被克隆出来。作为研究ZHX1作为转录抑制因子作用机制的第一步，我们利用酵母双杂交系统搜索与ZHX1相互作用的蛋白。克隆出了诸如ZHX1、转录辅因子和DNA结合蛋白、斑联蛋白、雄激素诱导的醛糖还原酶和富含11-19位赖氨酸的白血病基因等核蛋白，以及一些未知蛋白。对编码一种新蛋白的全长cDNA进行分子克隆和核苷酸序列测定，结果显示它由956个氨基酸残基组成，包含两个锌指（Znf）基序、五个同源结构域（HDs）以及ZHX1。我们得出结论，该蛋白与ZHX1构成ZHX家族，并将其命名为ZHX3。ZHX3不仅能与ZHX1和ZHX3自身形成二聚体，还能与NF-YA的激活域相互作用。进一步分析表明，ZHX3是一种广泛存在的转录抑制因子，定位于细胞核且以二聚体形式发挥作用。最后，二聚化结构域、与NF-YA的相互作用结构域以及抑制结构域被定位到包括HD1区域的一个区域，两个核定位信号分别通过Znf1和HD2区域定位到N端。
