The su(Hw) insulator can disrupt enhancer-promoter interactions when located more than 20 kilobases away from the Drosophila achaete-scute complex.

Here we report that the su(Hw) insulator may not necessarily separate promoters from enhancers to allow inhibition of transcription by the su(Hw) protein. For this purpose we used the strains of Drosophila melanogaster which carry inversion of the region containing the yellow gene and the achaete-scute complex (AS-C). Despite the reverse orientation of the region, the AS-C enhancers continue to activate achaete and scute gene expression. The su(Hw) insulator, located more than 20 kb away from the inversion, facilitates strong suppression of achaete and scute gene expression, although is does not separate the promoters from the AS-C enhancers.