Ramírez-Parra E, Xie Q, Boniotti M B, Gutierrez C
Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Nucleic Acids Res. 1999 Sep 1;27(17):3527-33. doi: 10.1093/nar/27.17.3527.
Association of the retinoblastoma (Rb) protein with E2F transcription factors is central to cell cycle-specific gene expression and growth in animal cells. Whether Rb-E2F complexes are also involved in plant cell growth and differentiation is still unknown since E2F proteins have not yet been identified in plants. Here we report the isolation and characterisation of a wheat E2F (TmE2F) cDNA clone. Interestingly, the overall domain organisation of plant E2F is related to the human E2F-1/2/3 subset but its primary sequence is slightly more related to the E2F-4/5 subset. TmE2F-Rb binding depends on residues, located at the C-terminus, which are different from those of animal E2Fs. However, the acidic or hydrophobic nature of certain residues is maintained, strongly suggesting that they may have a crucial role in E2F activities. Plant E2F is expressed in proliferating cultured cells and in differentiated tissues and is up-regulated early in S phase. Our studies reinforce the idea that G(1)/S regulators in plants are unrelated to those of yeast cells but similar to those of animal cells and provide new tools to analyse the links between cell cycle regulators, plant growth and developmental signals.
视网膜母细胞瘤（Rb）蛋白与E2F转录因子的结合对于动物细胞中细胞周期特异性基因表达和生长至关重要。由于尚未在植物中鉴定出E2F蛋白，Rb-E2F复合物是否也参与植物细胞生长和分化仍不清楚。在此，我们报道了一个小麦E2F（TmE2F）cDNA克隆的分离和鉴定。有趣的是，植物E2F的整体结构域组织与人类E2F-1/2/3亚组相关，但其一级序列与E2F-4/5亚组的关系更为密切。TmE2F与Rb的结合取决于位于C末端的残基，这些残基与动物E2F的不同。然而，某些残基的酸性或疏水性得以保留，这强烈表明它们可能在E2F活性中起关键作用。植物E2F在增殖的培养细胞和分化组织中表达，并在S期早期上调。我们的研究强化了这样一种观点，即植物中的G(1)/S调节因子与酵母细胞的不同，但与动物细胞的相似，并为分析细胞周期调节因子、植物生长和发育信号之间的联系提供了新工具。
