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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] A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase.
RNA polymerase II holoenzyme. 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 molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that catalyzes the chemical reactions that synthesize RNA from a DNA template. Using the enzyme helicase, RNAP locally opens the double-stranded DNA so that one strand of the exposed nucleotides can ...
Sigma factor. A sigma factor (σ factor or specificity factor) is a protein needed for initiation of transcription in bacteria. [1][2] It is a bacterial transcription initiation factor that enables specific binding of RNA polymerase (RNAP) to gene promoters. It is homologous to archaeal transcription factor B and to eukaryotic factor TFIIB. [3]
A transcription factor is a protein that binds to specific DNA sequences (enhancer or promoter), either alone or with other proteins in a complex, to control the rate of transcription of genetic information from DNA to messenger RNA by promoting (serving as an activator) or blocking (serving as a repressor) the recruitment of RNA polymerase. [3 ...
RNA polymerase core enzyme binds to the bacterial general transcription (sigma) factor to form RNA polymerase holoenzyme and then binds to a promoter. [6] (RNA polymerase is called a holoenzyme when sigma subunit is attached to the core enzyme which is consist of 2 α subunits, 1 β subunit, 1 β' subunit only).
The quaternary structure refers to the number and arrangement of the protein subunits with respect to one another. [2] Examples of proteins with quaternary structure include hemoglobin, DNA polymerase, ribosomes, antibodies, and ion channels. Enzymes composed of subunits with diverse functions are sometimes called holoenzymes, in which some ...
DNA polymerase III holoenzyme. Schematic picture of DNA polymerase III* (with subunits). This is the old textbook "trombone model" with two units of Pol III. DNA polymerase III holoenzyme is the primary enzyme complex involved in prokaryotic DNA replication. It was discovered by Thomas Kornberg (son of Arthur Kornberg) and Malcolm Gefter in 1970.