Drosophila hyperplastic discs encodes and E6-AP type ubiquitin protein ligase involved in cell proliferation control.

果蝇增生盘（byd）基因的产物HIT是调节想象盘细胞增殖和模式形成所必需的。序列比较表明，HYD含有一个类似于E6-AP的推定催化结构域的区域，E6-E6-P是一种与人乳头瘤病毒蛋白E6-P相关的细胞蛋白，E6-E6-P具有泛素蛋白连接酶活性。为了证明HYD在功能上与E6-P相似，我们发现HYD与果蝇泛素结合酶结合，该酶由混合基因编码，HYD与泛素结合酶在依赖于该E2酶的反应中形成硫酯。编码泛素激活酶的基因突变，以及编码蛋白酶体成分的基因突变，增强了杂交突变的表型，这表明这些基因的产物共同作用，控制泛素化和随后的蛋白质降解，这些蛋白质降解是果蝇想象盘细胞增殖和模式形成所必需的。

The product of the hyperplastic discs (byd) gene of Drosophila, HIT, is required for regulating imaginal disc cell proliferation and pattern formation. Sequence comparisons revealed that HYD contains a region similar to the putative catalytic domain of E6-AP, a cellular protein that associates with a human papillomavirus protein of E6-P, E6-E6-P has ubiquitin-protein ligase activity. As evidence that HYD is functionally similar to E6-P, we show that HYD associates with a Drosophila ubiquitin conjugating enzyme encoded by the bendless gene and that HYD forms a thioester with ubiquitin in a reaction dependent on this E2 enzyme. Mutation in the gene encoding an ubiquitin activating enzyme, in bendless, and in a gene encoding a proteasome component fins26, enhance the phenotype of hyd mutations suggesting that the products of these genes work together to control ubiquitinatin and subsequent degradation of proteins required for cell proliferation and pattern formation in Drosophila imaginal discs.