Krebs J E, Dunaway M
Department of Molecular and Cell Biology, University of California, Berkeley 94720-3202, USA.
Mol Cell. 1998 Jan;1(2):301-8. doi: 10.1016/s1097-2765(00)80030-1.
The Xenopus rRNA enhancer activates its cognate promoter when the two elements are placed on opposite rings of dimeric catenanes. Here we show that when scs elements flank either the enhancer or promoter in catenanes, the enhancer cannot activate the promoter on the ring in trans. A series of catenanes containing different permutations of the insulators, enhancer, and promoters shows that when insulators are present, the enhancer is permitted to a activate the promoter only when both elements are on the same piece of DNA with no intervening insulator. These results suggest that insulators have the potential to block enhancer-promoter interactions between chromosomes and between independent topological domains within a chromosome.
当非洲爪蟾核糖体RNA（rRNA）增强子和其同源启动子位于二聚连环体的相对环上时，增强子可激活启动子。在此我们表明，当隔离子元件位于连环体中增强子或启动子的侧翼时，增强子无法反式激活环上的启动子。一系列包含绝缘子、增强子和启动子不同排列组合的连环体显示，当存在绝缘子时，只有当增强子和启动子位于同一段无间隔绝缘子的DNA上时，增强子才能够激活启动子。这些结果表明，隔离子有可能阻断染色体之间以及染色体内独立拓扑结构域之间的增强子-启动子相互作用。
