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The RNA polymerase core associates with the sigma factor to form RNA polymerase holoenzyme. Sigma factor reduces the affinity of RNA polymerase for nonspecific DNA while increasing specificity for promoters, allowing transcription to initiate at correct sites. The core enzyme of RNA polymerase has five subunits (protein subunits) (~400 kDa). [14]
Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames will be "open" (the "reading", however, refers to the RNA produced by transcription of the DNA and its subsequent interaction with the ribosome in translation).
The Inr element for core promoters was found to be more prevalent than the TATA box in eukaryotic promoter domains. [11] In a study of 1800+ distinct human promoter sequences it was found that 49% contain the Inr element while 21.8% contain the TATA box. [11] Out of those sequences with the TATA box, 62% contained the Inr element as well.
RNA polymerase, assisted by one or more general transcription factors, then unwinds approximately 14 base pairs of DNA to form an RNA polymerase-promoter open complex. In the open complex, the promoter DNA is partly unwound and single-stranded. The exposed, single-stranded DNA is referred to as the "transcription bubble". [6]
In genetics, a promoter is a sequence of DNA to which proteins bind to initiate transcription of a single RNA transcript from the DNA downstream of the promoter. The RNA transcript may encode a protein , or can have a function in and of itself, such as tRNA or rRNA.
Promoter activity of the P-RM and P-R promoters vs RNA polymerase concentration in the enterobacteriophage lambda [1]. Promoter activity is a term that encompasses several meanings around the process of gene expression from regulatory sequences —promoters [2] and enhancers. [3]
Eukaryotic Transcription. Eukaryotic transcription is the elaborate process that eukaryotic cells use to copy genetic information stored in DNA into units of transportable complementary RNA replica. [1] Gene transcription occurs in both eukaryotic and prokaryotic cells. Unlike prokaryotic RNA polymerase that initiates the transcription of all ...
RNA polymerase II holoenzyme is a form of eukaryotic RNA polymerase II that is recruited to the promoters of protein-coding genes in living cells. [ 1 ] [ 2 ] It consists of RNA polymerase II , a subset of general transcription factors , and regulatory proteins known as SRB proteins [ clarification needed ] .