Promoter Guide, Meaning , Facts, Information and Description
In genetics, a promoter is a DNA sequence that enables a gene to be transcribed. The promoter is recognized by RNA polymerase, which then initiates transcription.The perfect promoter is called a canonical sequence.
| Table of contents |
|
2 Promoter sequences 3 Binding |
Promoter elements
Promoter sequences
Prokaryotic promoters
In prokaryotes, the promoter consists of two short sequences at -10 and -35 position upstream of the gene, that is, prior to the gene in the direction of transcription. The sequence at -10 is called the Pribnow box and usually consists of the six nucleotides TATAAT. The Pribnow box is absolutely essential to start transcription in prokaryotes. The other sequence at -35 usually consists of the six nucleotides TTGACA. Its presence allows a very high transcription rate.
<-- upstream downstream -->
5'-XXXXXXXPPPPPXXXXXXPPPPPXXXXGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGXXXX-3'
-35 -10 Gene to be transcribed
Probability of occurrence of each nucleotide
T A T A A T 77% 76% 60% 61% 56% 82%T T G A C A 69% 79% 61% 56% 54% 54%
Eukaryotic promoters
See Michael Levine and Robert Tjian. "Transcription regulation and animal diversity". Nature 424, 147 - 151 (10 July 2003) [1]
Binding
The binding of a promoter sequence (P) to a sigma factor-RNAP complex (R) is a two step process:
- R+P ↔ RP(closed). K = 10E7
- RP(closed) --> RP(open). K = 10E-2
This is an Article on Promoter. Page Contains Information, Facts Details or Explanation Guide About Promoter