Enhancer and silencer sequences

[motornoob101]

In all the stuff I read, enhancer only binds activators while silencer sequences on DNA binds repressors. However, in my biology's slides.. my professor is saying that repressors can bind to both silencers and enhancers.. can anyone confirm this? This is very fishy as I have never read this before and it would kind of defeat the purpose of enhancer sequences no? Thanks!

 

[JonMoulton]

There is no "purpose of enhancer sequences", these are just nucleotide sequences. They can be bound by whatever protein evolves to recognize them. A protein can enhance or repress gene expression depending on how it interacts with other macromolecules when bound to the nucleotide sequence for which it has affinity. Don't let your thinking about the system be restricted by the nomenclature, the proteins determine what happens.