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RNA polymerase II (RNAP II and Pol II) is a multiprotein complex that transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. [ 1 ] [ 2 ] It is one of the three RNAP enzymes found in the nucleus of eukaryotic cells. [ 3 ]
RNA polymerase II (also called RNAP II and Pol II) is an enzyme found in eukaryotic cells. It catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA . [ 3 ] [ 4 ] In humans, RNAP II consists of seventeen protein molecules (gene products encoded by POLR2A-L, where the proteins synthesized from POLR2C ...
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.
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.
The initiation of the transcription is a multistep sequential process that involves several mechanisms: promoter location, initial reversible binding of RNA polymerase, conformational changes in RNA polymerase, conformational changes in DNA, binding of nucleoside triphosphate (NTP) to the functional RNA polymerase-promoter complex, and ...
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. [2]
Figure 2. Mechanism for transcription initiation at the TATA box. Transcription factors, TATA binding protein (TBP), and RNA polymerase II are all recruited to begin transcription. The TATA box is a component of the eukaryotic core promoter and generally contains the consensus sequence 5'-TATA(A/T)A(A/T)-3'. [3]
The added complexity of generating a eukaryotic cell carries with it an increase in the complexity of transcriptional regulation. Eukaryotes have three RNA polymerases, known as Pol I, Pol II, and Pol III. Each polymerase has specific targets and activities, and is regulated by independent mechanisms.