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In molecular biology, a transcription factor
is a protein that binds DNA at a specific
promoter or enhancer region or site,
where it regulates transcription. Transcription
factors can be selectively activated or deactivated by other proteins, often as the final step in signal transduction.
Classes
There are three classes of transcription factors:
- General transcription factors are involved in the formation of a preinitiantion
complex.
- Upstream transcription factors are unregulated proteins that bind somewhere upstream of the
initiation site to stimulate or repress transcription.
- Inducible transcription factors are similar to upstream transcription factors but require
activation or inhibition.
Motifs found in transcription factors
- Zinc fingers function as structural platforms for DNA binding.
- Leu zippers function in
associating the transcription factors with eachother.
See also
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