An insulator is a DNA sequence that can act as a barrier to the influences of neighboring cis-acting elements, preventing gene activation, for example, when located between an enhancer and a promoter. We have identified a 42 bp fragment of the chicken beta-globin insulator that is both necessary and sufficient for enhancer blocking activity in human cells. We show that this sequence is the binding site for CTCF, a previously identified eleven-zinc finger DNA-binding protein that is highly conserved in vertebrates. CTCF sites are present in all of the vertebrate enhancer-blocking elements we have examined. We suggest that directional enhancer blocking by CTCF is a conserved component of gene regulation in vertebrates.
Pubmed ID: 10458613 RIS Download
Mesh terms: Amino Acid Sequence | Animals | Base Sequence | Binding Sites | Cell Nucleus | Chickens | Conserved Sequence | DNA-Binding Proteins | Deoxyribonuclease I | Enhancer Elements, Genetic | Genetic Variation | Globins | Humans | K562 Cells | Molecular Sequence Data | Oligodeoxyribonucleotides | Protein Biosynthesis | Repressor Proteins | Transcription Factors | Vertebrates | Zinc Fingers
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