Ekker S C, von Kessler D P, Beachy P A
Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
EMBO J. 1992 Nov;11(11):4059-72. doi: 10.1002/j.1460-2075.1992.tb05499.x.
The homeotic genes of Drosophila encode transcriptional regulatory proteins that specify distinct segment identities. Previous studies have implicated the homeodomain as a major determinant of biological specificity within these proteins, but have not established the physical basis of this specificity. We show here that the homeodomains encoded by the Ultrabithorax and Deformed homeotic genes bind optimally to distinct DNA sequences and have mapped the determinants responsible for differential recognition. We further show that relative transactivation by these two proteins in a simple in vivo system can differ by nearly two orders of magnitude. Such differences in DNA sequence recognition and target activation provide a biochemical basis for at least part of the biological specificity of homeotic gene action.
果蝇的同源异型基因编码转录调节蛋白，这些蛋白决定了不同体节的特征。先前的研究表明，同源异型结构域是这些蛋白中生物学特异性的主要决定因素，但尚未确定这种特异性的物理基础。我们在此表明，由超双胸和畸形同源异型基因编码的同源异型结构域与不同的DNA序列具有最佳结合，并已确定了负责差异识别的决定因素。我们进一步表明，在一个简单的体内系统中，这两种蛋白的相对反式激活作用可能相差近两个数量级。DNA序列识别和靶标激活方面的这种差异为同源异型基因作用的至少部分生物学特异性提供了生化基础。
