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[5] [6] The core RNA polymerase complex forms a "crab claw" or "clamp-jaw" structure with an internal channel running along the full length. [7] Eukaryotic and archaeal RNA polymerases have a similar core structure and work in a similar manner, although they have many extra subunits.
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.
RNA polymerase III (Pol III) transcribes small non-coding RNAs, including tRNAs, 5S rRNA, U6 snRNA, SRP RNA, and other stable short RNAs such as ribonuclease P RNA. [7] Structure of eukaryotic RNA polymerase II (light blue) in complex with α-amanitin (red), a strong poison found in death cap mushrooms that targets this vital enzyme
RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template.
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.
RNA can also act as a hereditary molecule, which encouraged Walter Gilbert to propose that in the distant past, the cell used RNA as both the genetic material and the structural and catalytic molecule rather than dividing these functions between DNA and protein as they are today; this hypothesis is known as the "RNA world hypothesis" of the ...
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).
Pol I is a 590 kDa enzyme that consists of 14 protein subunits (polypeptides), and its crystal structure in the yeast Saccharomyces cerevisiae was solved at 2.8Å resolution in 2013. [2] Twelve of its subunits have identical or related counterparts in RNA polymerase II (Pol II) and RNA polymerase III (Pol III). The other two subunits are ...