For initiation of transcription, the DNA-dependent RNA polymerase must bind to the promoter region of one strand of the DNA template. (PIC). RNA polymerase requires a number of general transcription factors (TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH). TFIID is a complex of a TATA box binding protein (TBP) plus several proteins designated TATA binding protein-associated factors (TAFs).
Many promoters contain a DNA sequence called the TATA box, which is located 25 nucleotides away from the site of initiation of transcription. The TATA box is recognized and bound by transcription factor TFIID, which then enables the adjacent binding of TFIIB. The rest of the general transcription factors plus the RNA polymerase assemble at the promoter.
Find on/off : Find start : Find stop : diagram - initiation of transcription : ball-stick - dna double helix : animation - adenine tyrosine H bonds : animation - cytosine guanine H bonds : animation - start of transcription :
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In general, a consensus sequence is that idealized sequence in which each position represents the base/amino acid most often found when many sequences are compared. A genetic consensus sequence is a sequence of nucleotides that is common to different genes or genomes. There may be some variations but such sequences show considerable similarity. So, a consensus sequence is the prototype sequence that most others approach.
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