Chromatin Boundaries and Chromatin Domains
This extract was created in the absence of an abstract.
Excerpt
Insulator elements were first described in Drosophila,but subsequent studies have shown that they are presentin vertebrates as well (for review, see West et al. 2002).Over the past several years we have focused our attentionon the properties of an insulator at the 5′ end of thechicken β-globin locus that has begun to provide an understanding of how such elements function. This work, aswell as studies in other laboratories, has revealed thatthere are two distinct kinds of insulator activities, whichare different in their function. The first of these is the enhancer-blocking activity, which can prevent interactionbetween a distal enhancer and a promoter when placedbetween them (Fig. 1A). This has the effect of preventingan incorrect interaction between regulatory elements inadjacent, but separately regulated, gene systems. The second insulator function is connected with barrier activity,which prevents condensed heterochromatin from extending into adjacent chromatin domains carrying transcriptionally active genes (Fig. 1B)...
