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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.
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.
T7 RNA polymerase binds to the promoter region on the double strand. Since T7 RNA polymerase can only transcribe in the 3' to 5' direction [15] the sense DNA is transcribed and an anti-sense RNA is produced. This is repeated, and the polymerase continuously produces complementary RNA strands of this template which results in amplification.
Synthesis of RNA typically occurs in the cell nucleus and is usually catalyzed by an enzyme—RNA polymerase—using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found "upstream" of a gene).
This allows the RNA polymerase to bind to the mal promoter (#3). Transcription of malE, malF, and malG genes then proceeds (#4) as maltose activator protein and RNA polymerase moves down the DNA. [1] malE encodes for maltose-binding periplasmic protein and helps maltose transport across the cell membrane.
The movement of the RNA-DNA complex is essential for the catalytic mechanism of RNA polymerase. Additionally, RNA polymerase increases the overall stability of this process by acting as a link between the RNA and DNA strands. [18] New nucleotides that are complementary to the DNA template strand are added to the 3' end of the RNA strand. [4]
RNA polymerase 1 (also known as Pol I) is, in higher eukaryotes, the polymerase that only transcribes ribosomal RNA (but not 5S rRNA, which is synthesized by RNA polymerase III), a type of RNA that accounts for over 50% of the total RNA synthesized in a cell.
In eukaryote cells, RNA polymerase III (also called Pol III) is a protein that transcribes DNA to synthesize 5S ribosomal RNA, tRNA, and other small RNAs. The genes transcribed by RNA Pol III fall in the category of "housekeeping" genes whose expression is required in all cell types and most environmental conditions.