Lin L, McGinnis W
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511.
Genes Dev. 1992 Jun;6(6):1071-81. doi: 10.1101/gad.6.6.1071.
To define homeo domain subregions that are important for embryonic targeting specificity of homeotic proteins, we generated a series of Deformed/Ultrabithorax chimeric genes in which parts of the Deformed homeo box region were substituted with Ultrabithorax sequences. Chimeric coding regions were attached to heat shock promoters and introduced into the Drosophila genome by P-element transformation. After heat-induced ectopic expression in embryos, we examined the cuticular phenotypes induced by the resulting chimeric proteins. We also tested the ability of the chimeric proteins to regulate transcription units that are normal targets of Deformed and Ultrabithorax. Our results indicate that specific amino acid residues at the amino end of the Ultrabithorax homeo domain are required to specifically regulate Antennapedia transcription; and in the context of a Deformed protein, these amino-end residues are sufficient to switch from Deformed- to Ultrabithorax-like targeting specificity. Although residues in the amino end of the homeo domain are also important in determining a Deformed-like targeting specificity, other regions of the Deformed homeo domain are also required for full activity.
为了确定对同源异型蛋白胚胎靶向特异性至关重要的同源结构域亚区域，我们构建了一系列变形/超双胸嵌合基因，其中变形同源框区域的部分被超双胸序列取代。嵌合编码区连接到热休克启动子上，并通过P因子转化引入果蝇基因组。在胚胎中热诱导异位表达后，我们检查了所得嵌合蛋白诱导的表皮表型。我们还测试了嵌合蛋白调节变形和超双胸正常靶标的转录单位的能力。我们的结果表明，超双胸同源结构域氨基端的特定氨基酸残基是特异性调节触角足转录所必需的；并且在变形蛋白的背景下，这些氨基端残基足以从变形样靶向特异性转变为超双胸样靶向特异性。尽管同源结构域氨基端的残基在确定变形样靶向特异性方面也很重要，但变形同源结构域的其他区域对于完全活性也是必需的。
