(85)
2. Beskrive hvordan kromatin struktur over store afstande kan regulere genekspression
Devlin, s.347-9
Devlin, s.214-5
Stryer, s.876-8

The chromatin structure can regulate the gene expression over large distance thru enhancers.

Enhancers are DNA-sequences, 20-30 nuleotides that can be placed thousands bp upstream or downstream the gene of interest, on the same or the complementary strand of DNA or even in the middle of the gene.

Enhancers have no promoter activity of their own, but greatly increase the activity of many promoters, by serving as binding sites for specific regulatory proteins. This DNA-protein interaction perturbs the local chromatin structure and exposes the promoter or the gene of interest, so it is available for transcription.

Basically, enhancers need to be made of euchromatine (acetylated histones which have weaker electrostatic interactions with the DNA and therefore a looser structure). Their major groove also needs to be available for protein interactions (maybe A=T rich region).

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