Specificity factor
Encyclopedia
Specific Transcription Factors -Eukaryotic transcription begins with the formation of a pre initiation complex formed by the fusion of a group of general transcription factors. Proteins that maintain control over transcription at specific promoters are the specific transcription factors.
These proteins generally have two domains, a domain that recognizes a specific DNA sequence and a domain that recognizes another protein like the pre initiation complex.A majority of specific transcription factors act by recruiting the components of the RNA polymerase holoenzyme.
Thus, the binding of a specific transcription factor at a promoter is the first step in the formation of a pre-initiation complex at the promoter of a gene, e.g. dorsal wing development in drosophila.
Bacterial specific factor
the sigma subunit of the E.coli RNA polymerase holoenzymeis the specificity factor that mediate the promoter recognization & binding σ subunit(Mr 70,000).
under some condition , some of the σ(Mr 70,000)subunit are replaced by one of the other specific factor.
when the bacteria are subjected to heat stress,leading to the replacement of σ(Mr 70,000) by a σ(Mr 32,000),when bound to σ32,RNA polymerase is directed to a specialized set of promoter with a different consensus sequence.
These proteins generally have two domains, a domain that recognizes a specific DNA sequence and a domain that recognizes another protein like the pre initiation complex.A majority of specific transcription factors act by recruiting the components of the RNA polymerase holoenzyme.
Thus, the binding of a specific transcription factor at a promoter is the first step in the formation of a pre-initiation complex at the promoter of a gene, e.g. dorsal wing development in drosophila.
Bacterial specific factor
the sigma subunit of the E.coli RNA polymerase holoenzymeis the specificity factor that mediate the promoter recognization & binding σ subunit(Mr 70,000).
under some condition , some of the σ(Mr 70,000)subunit are replaced by one of the other specific factor.
when the bacteria are subjected to heat stress,leading to the replacement of σ(Mr 70,000) by a σ(Mr 32,000),when bound to σ32,RNA polymerase is directed to a specialized set of promoter with a different consensus sequence.