5′ flanking region

In eukaryotes, the 5′ flanking region has a complex set of regulatory elements such as enhancers, silencers, and promoters.

[1] Enhancers are DNA sequences found in 5′ flanking regions of eukaryotic genes that affect transcription.

[3] When repressors bind silencers, they act in a similar fashion as enhancers and bend over to prevent the interaction of RNA polymerase with promoters.

This is followed by binding of transcription factor TFIID, which then recruits TFIIB, TFIIF, RNA polymerase II and TFIIH (in that order) to form an initiation complex.

A 12 base pair insertion in the 5′ flanking region of the Cystatin B gene has been linked to some individuals with Unverricht-Lundborg disease.

[6] Polymorphisms in the 5′ flanking region of the DRD4 gene have been linked to ADHD, schizophrenia and methamphetamine abuse.

[7] Insertions and deletions in the 5′ flanking region of the insulin gene have been associated with type 2 diabetes.

Structure of a eukaryotic gene. 5′ flanking region is shown in yellow on the left of the DNA strand. Since it is not transcribed, it is no longer present in the RNA or protein form.