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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