The best characterized core promoter element is the TATA box
- a DNA sequence that is rich in A-T base pairs
- located 25 base pairs upatream of the transcription start site.
The TATA box is recognized by one of the basal transcription factors
- TATA box-binding protein, TBP.
- part of a multisubunit complex called TFIID.
- in combination with RNA polymerase II and other transcription
factors ( TFIIA, TFIIB ) form a preinitiation complex.
Transcription is activated by protein-protein interactions The specific transcription factors usually have two different functions
- to bind to a specific DNA sequence.
- to activate transcription.
The DNA binding domains are usually
- short polypeptide chain of around 100 residues.
- bind to short DNA region of less 20 nucleotides.
Four most important families of specific transcription factors
- account for 80% of the known TF- helix-turn-helix
- leucine zipper
- zinc finger
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