Rauskolb C, Peifer M, Wieschaus E
Department of Molecular Biology, Princeton University, New Jersey 08544.
Cell. 1993 Sep 24;74(6):1101-12. doi: 10.1016/0092-8674(93)90731-5.
Mutations in the Drosophila gene extradenticle (exd) cause homeotic transformations by altering the morphological consequences of homeotic selector gene activity. We have cloned and sequenced exd: it encodes a homeodomain protein with extensive identity (71%) to the human proto-oncoprotein Pbx1. exd is expressed during embryogenesis when the selector homeodomain proteins of the Antennapedia and bithorax complexes establish segmental identity. Maternally expressed exd is uniform and can suppress the segmental transformations of embryos lacking zygotic exd. While zygotic exd expression is also at first uniform, later expression is modulated by the homeotic selector genes. These studies support the view that exd acts with the selector homeodomain proteins as a DNA-binding transcription factor, thereby altering their regulation of downstream target genes.
果蝇额外齿基因（exd）的突变通过改变同源异型选择基因活性的形态学结果而导致同源异型转化。我们已经克隆并测序了exd：它编码一种与人类原癌蛋白Pbx1具有广泛同源性（71%）的同源结构域蛋白。exd在胚胎发育期间表达，此时触角足复合体和双胸复合体的选择同源结构域蛋白确立节段身份。母体表达的exd是均匀的，并且可以抑制缺乏合子exd的胚胎的节段转化。虽然合子exd的表达起初也是均匀的，但后来的表达受到同源异型选择基因的调节。这些研究支持这样一种观点，即exd与选择同源结构域蛋白一起作为一种DNA结合转录因子发挥作用，从而改变它们对下游靶基因的调控。
