DeCamillis M, Cheng N S, Pierre D, Brock H W
Department of Zoology, University of British Columbia, Vancouver, Canada.
Genes Dev. 1992 Feb;6(2):223-32. doi: 10.1101/gad.6.2.223.
The Polycomb group (PcG) genes in Drosophila melanogaster are required for maintenance of correct spatial expression of homeotic genes, and their products are thought to form either a regulatory network or act as a multimeric complex. Recently, it has been suggested that because of homology between Polycomb (Pc) and Su(var)205, PcG genes encode chromatin proteins required for the maintenance of a determined state in chromatin. The polyhomeotic (ph) gene is a member of the PcG of genes. We present DNA sequence of a ph cDNA, which encodes a 169-kD protein with a single putative zinc finger, a serine/threonine-rich region, and has glutamine repeats, suggesting that ph is a DNA-binding protein. Polyclonal antisera directed against ph protein bind to approximately 80 sites on polytene chromosomes. Most of these sites appear to be the same as those recognized by antibodies to Pc protein. ph protein binds to insertion sites of constructs containing DNA from the bithoraxoid (bxd) region of the Bithorax complex, showing that ph binding to chromatin is DNA dependent. The same bxd constructs are recognized by Pc protein, strongly supporting the hypothesis that ph and Pc interact directly.
果蝇中的多梳蛋白组（PcG）基因对于维持同源异型基因正确的空间表达是必需的，并且其产物被认为要么形成一个调控网络，要么作为一个多聚体复合物发挥作用。最近，有人提出，由于多梳蛋白（Pc）与Su(var)205之间存在同源性，PcG基因编码维持染色质特定状态所需的染色质蛋白。多同源异型（ph）基因是PcG基因家族的成员。我们给出了一个ph cDNA的DNA序列，它编码一个169-kD的蛋白，该蛋白具有一个假定的锌指、一个富含丝氨酸/苏氨酸的区域并且有谷氨酰胺重复序列，这表明ph是一种DNA结合蛋白。针对ph蛋白的多克隆抗血清与多线染色体上大约80个位点结合。这些位点中的大多数似乎与Pc蛋白抗体识别的位点相同。ph蛋白与含有来自双胸复合体双胸样（bxd）区域DNA的构建体的插入位点结合，表明ph与染色质的结合是依赖于DNA的。相同的bxd构建体也被Pc蛋白识别，这有力地支持了ph和Pc直接相互作用的假说。
