Insulator

Updated by Hongjiang on 10/21/2022

Human insulators bind a protein called CTCF(CCCCTC-binding factor). Connections between CTCF proteins bound to different insulators facilitate the formation of DNA loops. A promoter and an enhancer will be in separate loops and cannot interact with each other if an insulator lies between them.

CTCF

CCCTC-binding factor (CTCF) is a highly conserved zinc finger, which can act as a transcriptional activator, repressor or insulator protein, blocking the communication between enhancers and promoters. CTCF can also recruit other transcription factors while binding to chromatin domain boundaries.

The 3D organization of the eukaryotic genome determines its function, and CTCF is one of the core structural proteins that help establish this organization. The mapping results of CTCF binding sites in a large number of different species show that the genome is covered by CTCF binding sites.

H19和Igf2基因表达由ICR处的CTCF结合控制。CTCF无法与甲基化的ICR(父本)(paternal)结合，在这种情况下，增强子(E)可以诱导Igf2基因表达。

CTCF可与未甲基化的ICR(母本)(maternal)结合充当Igf2基因和增强子之间的障碍，激活 H19 基因表达。

CTCF as a multifunctional protein in genome regulation and gene expression