Imoto I, Sonoda I, Yuki Y, Inazawa J
Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, 113-8510 Tokyo, Japan.
Biochem Biophys Res Commun. 2001 Sep 14;287(1):270-6. doi: 10.1006/bbrc.2001.5578.
The three-amino-acid loop extension (TALE) homeodomain proteins are highly conserved transcription regulators. Since cooperative function among members of this growing family is critical for regulating transcription, we have tried to explore novel members to understand their regulatory mechanisms in cellular proliferation and differentiation. Here we report identification of PKNOX2, a novel TALE homeodomain protein that shows distinct homology with PKNOX1, a stable partner of PBX proteins. PKNOX2 is composed of 460 amino acids and contains HR1, HR2, and homeodomain, which are highly similar to PKNOX1, suggesting that PKNOX2 may also interact with PBX proteins as well as the same DNA sequence as PKNOX1. Genomic organization of PKNOX2 also showed high similarity to PKNOX1, though PKNOX2 lies on a different chromosomal region, 11q24. Unlike PKNOX1, which was broadly expressed in many tissues, PKNOX2 showed a more restricted pattern of mRNA expression. Nuclear localization of PKNOX2 was confirmed by transfection of epitope-tagged cDNA. Taken together, these data indicate that PKNOX2 is a novel PKNOX-related protein and may interact with PBX proteins and play a tissue-specific regulation of transcription.
三氨基酸环延伸（TALE）同源结构域蛋白是高度保守的转录调节因子。由于这个不断扩大的家族成员之间的协同功能对于调节转录至关重要，我们试图探索新的成员以了解它们在细胞增殖和分化中的调节机制。在此，我们报告了PKNOX2的鉴定，它是一种新型的TALE同源结构域蛋白，与PBX蛋白的稳定伴侣PKNOX1具有明显的同源性。PKNOX2由460个氨基酸组成，包含HR1、HR2和同源结构域，这些与PKNOX1高度相似，表明PKNOX2可能也与PBX蛋白相互作用，并与PKNOX1结合相同的DNA序列。PKNOX2的基因组结构也显示出与PKNOX1高度相似，尽管PKNOX2位于不同的染色体区域11q24。与在许多组织中广泛表达的PKNOX1不同，PKNOX2显示出更局限的mRNA表达模式。通过转染表位标记的cDNA证实了PKNOX2的核定位。综上所述，这些数据表明PKNOX2是一种新型的PKNOX相关蛋白，可能与PBX蛋白相互作用并在转录中发挥组织特异性调节作用。
