期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1997
卷号：94
期号：2
页码：575-580
DOI：10.1073/pnas.94.2.575
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Insulators, first identified in Drosophila, are DNA sequence elements that shield a promoter from nearby regulatory elements. We have previously reported that a DNA sequence at the 5' end of the chicken {beta}-globin locus can function as an insulator. It is capable of shielding a reporter gene from the activating effects of a nearby mouse {beta}-globin locus control region element in the human erythroleukemic cell line K562. In this report, we show that most of the insulating activity lies in a 250-bp CpG island (core element), which contains the constitutive DNase I-hypersensitive site (5'HS4). DNA binding assays with the core sequence reveal a complex protein binding pattern. The insulating activity of the core element is multiplied when tandem copies are used. Although CpG islands are often associated with promoters of housekeeping genes, we find little evidence that the core element is a promoter. Furthermore, the insulator differs from a promoter in its ability to block the locus control region effect directionally.
