In mammals, a C2H2 zinc finger (C2H2) protein, CTCF, acts as the master regulator of chromosomal architecture and of the expression of Hox gene clusters. Like mammalian CTCF, the Drosophila homolog, dCTCF, localizes to boundaries in the bithorax complex (BX-C). Here, we have determined the minimal requirements for the assembly of a functional boundary by dCTCF and two other C2H2 zinc finger proteins, Pita and Su(Hw). Although binding sites for these proteins are essential for the insulator activity of BX-C boundaries, these binding sites alone are insufficient to create a functional boundary. dCTCF cannot effectively bind to a single recognition sequence in chromatin or generate a functional insulator without the help of additional proteins. In addition, for boundary elements in BX-C at least four binding sites for dCTCF or the presence of additional DNA binding factors is required to generate a functional insulator.

在哺乳动物中，C2H2锌指（C2H2）蛋白CTCF充当染色体结构和Hox基因簇表达的主要调节剂。像哺乳动物的CTCF，果蝇同源物dCTCF定位于Bithorax复合体（BX-C）的边界。在这里，我们已经确定了由dCTCF和另外两个C2H2锌指蛋白Pita和Su（Hw）组装功能边界的最低要求。尽管这些蛋白质的结合位点对于BX-C边界的绝缘子活性至关重要，但仅这些结合位点不足以形成功能性边界。没有其他蛋白质的帮助，dCTCF无法有效结合染色质中的单个识别序列或生成功能性绝缘子。此外，对于BX-C中的边界元素，需要至少四个dCTCF的结合位点或存在其他DNA结合因子来生成功能性绝缘子。