DNA Recognition by Eucaryotic Transcription
Factors
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
-
helix-loop-helix
-
zinc finger
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