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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. [11] It consists of RNA polymerase II, a subset of general transcription factors , and regulatory proteins known as SRB proteins.
In most prokaryotes, a single RNA polymerase species transcribes all types of RNA. RNA polymerase "core" from E. coli consists of five subunits: two alpha (α) subunits of 36 kDa, a beta (β) subunit of 150 kDa, a beta prime subunit (β′) of 155 kDa, and a small omega (ω) subunit. A sigma (σ) factor binds to the core, forming the holoenzyme.
This is part of the process that regulates the transcription of RNA to preserve gene expression integrity and are present in both eukaryotes and prokaryotes, although the process in bacteria is more widely understood. [1] The most extensively studied and detailed transcriptional termination factor is the Rho (ρ) protein of E. coli. [2]
There is only one type of bacterial RNA polymerase whereas eukaryotes have 3 types. [2] Bacteria have a σ-factor that detects and binds to promoter sites but eukaryotes do not need a σ-factor. Instead, eukaryotes have transcription factors that allow the recognition and binding of promoter sites.
Unlike prokaryotic RNA polymerase that initiates the transcription of all different types of RNA, RNA polymerase in eukaryotes (including humans) comes in three variations, each translating a different type of gene. A eukaryotic cell has a nucleus that separates the processes of transcription and translation.
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 ] .
In prokaryotes, activators tend to make contact with the RNA polymerase directly in order to help bind it to the promoter. [2] In eukaryotes, activators mostly interact with other proteins, and these proteins will then be the ones to interact with the RNA polymerase.
Transcription preinitiation complex, represented by the central cluster of proteins, causes RNA polymerase to bind to target DNA site. The PIC is able to bind both the promoter sequence near the gene to be transcribed and an enhancer sequence in a different part of the genome, allowing enhancer sequences to regulate a gene distant from it.