Transcription in eukaryotes is taken care of by RNA polymerases very similar to those present in prokaryotes. But it is a much more complex process and there are several notable differences :

 - Transcription in eukaryotes is taken care of by 3 RNA polymerases (Pol I, II, and III) very related to those present in prokaryotes.

 - Transcription, unlike translation, takes place at the level of the nucleus.

 - It requires several initiation factors (general transcription factors (FGT: TFII A, TFII B, TFII D (TBP, TAF), TFII E, TFIIH)

 Chromatin remodeling by regulatory proteins and chromatin modification enzymes ---->: conformation change during the opening of the DNA double helix (DNA included in the nucleosomes).

 - In additionto the ciselements (ex: TATABox) there areother sequences or control units in addition to the promoter:

·     OtherActivators: EnhancersEnhancers

·     Fire Extinguishers: Silencers.

Thesesequencescanbe locatedinthe regulatoryregionat 5', upstream ofthe initiationpoint, butalso sometimesinsidethe geneorevenin the 3' region downstreamof the codingsequence

Figure7:The componentsof a eukaryotic promoter.