van Dijk M A, Murre C
Department of Biology, University of California, San Diego, La Jolla 92093.
Cell. 1994 Aug 26;78(4):617-24. doi: 10.1016/0092-8674(94)90526-6.
Recently, a Drosophila gene has been identified, extradenticle, whose product modulates the morphological consequences of homeotic selector genes. We show here that extradenticle protein raises the DNA binding specificity of Ultrabithorax and abdominal-A but not that of Abdominal-B. We further show that extradenticle modulates the DNA binding activity of engrailed to a different target site. While a region N-terminal of the extradenticle homeodomain is required for Ultrabithorax and abdominal-A cooperativity, engrailed requires a domain C-terminal of the extradenticle homeobox. These studies show directly how the DNA binding specificity of selector gene products can be raised by extradenticle and provides a mechanism, cooperative DNA binding, that allows selector gene products to achieve some of their biological specificity.
最近，一种果蝇基因——额外齿（extradenticle）已被鉴定出来，其产物可调节同源异型选择基因的形态学效应。我们在此表明，额外齿蛋白提高了超双胸（Ultrabithorax）和腹部A（abdominal-A）的DNA结合特异性，但未提高腹部B（Abdominal-B）的DNA结合特异性。我们进一步表明，额外齿可调节成对控制基因（engrailed）对不同靶位点的DNA结合活性。虽然额外齿同源域N端的一个区域是超双胸和腹部A协同作用所必需的，但成对控制基因需要额外齿同源框C端的一个结构域。这些研究直接表明额外齿如何提高选择基因产物的DNA结合特异性，并提供了一种机制——协同DNA结合，使选择基因产物能够实现其一些生物学特异性。
