Eucharyothic Gene Transcription

Fig. 1. This picture shows the basic steps from DNA to protein.

Transcription Start

1: The promoter region has aTATA box, a DNA sequence located 25 nucleotides upstream from the transcription start point
2: TATA box is recogniced by the transcription factor TFIID, which binds TATAbox making easier the binding of TFIIB.
3: RNA polimeraseII and the rest of the factors binds the building complex.
4: FIIH induces a conformational change of RNA polimerasa,which will release the complex allowing the transcription begining.
5: Transcription Starts

The basal promoter
The basal promoter contains a sequence of 7 bases (TATAAAA) called the TATA box. It is bound by Transcription Factor IID (TFIID) which is a complex of some 10 different proteins including
TATA-binding protein (TBP), which recognizes and binds to the TATA box
other protein factors which bind to TBP - and each other - but not to the DNA.

The basal or core promoter is found in all protein-encoding genes. This is in sharp contrast to the upstream promoter whose structure and associated binding factors differ from gene to gene.

Although the figure is drawn as a straight line, the binding of transcription factors to each other probably draws the DNA of the promoter into a loop.

Many different genes and many different types of cells share the same transcription factors - not only those that bind at the basal promoter but even some of those that bind upstream. What turns on a particular gene in a particular cell is probably the unique combination of promoter sites and the transcription factors that are chosen.

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