A minimal RNA polymerase II (pol II) transcription system comprises the polymerase and five general transcription factors (GTFs) TFIIB, -D, -E, -F, and -H . The addition of Mediator enables a response to regulatory factors. The GTFs are required for promoter recognition and the initiation of transcription.
Which of the following types of RNA are transcribed by RNA polymerase II?
Eukaryotic cells contain three distinct nuclear RNA polymerases that transcribe different classes of genes (Table 6.1). Protein-coding genes are transcribed by RNA polymerase II to yield mRNAs ; ribosomal RNAs (rRNAs) and transfer RNAs (tRNAs) are transcribed by RNA polymerases I and III.
What is produced by RNA polymerase II?
RNA polymerase II catalyzes the synthesis of precursor mRNA . In eukaryotes, this RNA is generally longer than the final or “mature” mRNA, whose molecule is used as a template for protein synthesis.
Which way does RNA polymerase II transcribe?
Transcription of two genes. (a) RNA polymerase moves from the 3′ end of the template strand, creating an RNA strand that grows in a 5′ → 3′ direction (because it must be antiparallel to the template strand).
What is the function of RNA polymerase 2?
RNA polymerase II catalyzes the synthesis of precursor mRNA . In eukaryotes, this RNA is generally longer than the final or “mature” mRNA, whose molecule is used as a template for protein synthesis. Promoter. The promoter comprises three sites.
What is the difference between RNA polymerase 1 and 2?
The main difference between RNA Polymerase 1, 2 and 3 is that the RNA polymerase 1 (Pol 1) transcribes rRNA genes and, the RNA polymerase 2 (Pol 2) mainly transcribes mRNA genes while the RNA polymerase 3 (Pol 3) mainly transcribes tRNA genes.
What are different types of RNA polymerase?
All eukaryotes have three different RNA polymerases (RNAPs) which transcribe different types of genes. RNA polymerase I transcribes rRNA genes, RNA polymerase II transcribes mRNA, miRNA, snRNA, and snoRNA genes , and RNA polymerase III transcribes tRNA and 5S rRNA genes.
Is RNA polymerase II in prokaryotes?
Prokaryotes utilize one RNA polymerase for all transcription of types of RNA. In contrast, eukaryotes utilize three slightly different RNA polymerases: RNA polymerase I, RNA polymerase II, and RNA polymerase III (8). Each of the three RNA polymerases in eukaryotes is responsible for transcribing a unique type of RNA.
What happens to RNA polymerase II after it?
What happens to RNA polymerase II after it has completed transcription of a gene? The enzyme is free to transcribe other genes in the cell . ... RNA polymerase releases the completed RNA and detaches from the DNA.
Is RNA polymerase a protein?
As complex molecule composed of protein subunits , RNA polymerase controls the process of transcription, during which the information stored in a molecule of DNA is copied into a new molecule of messenger RNA.
What is CTD RNA polymerase II?
The C-terminal repeat domain (CTD), an unusual extension appended to the C terminus of the largest subunit of RNA polymerase II, serves as a flexible binding scaffold for numerous nuclear factors; which factors bind is determined by the phosphorylation patterns on the CTD repeats.
Is RNA polymerase 2 a transcription factor?
Like RNA polymerases I and III, polymerase II cannot act alone . Instead, general initiation factors [transcription factor (TF) IIB, TFIID, TFIIE, TFIIF, and TFIIH] assemble on promoter DNA with polymerase II, creating a large multiprotein–DNA complex that supports accurate initiation.
Where is the RNA polymerase II phosphorylated?
Unphosphorylated RNA Pol II assembles within the initiation complex at the promoter . At this stage, the CTD may interact with factors important for regulation of transcription initiation. The CTD is then phosphorylated at Ser 5 by the TFIIH kinase subunit.
What is the function of RNA polymerase 3?
In eukaryote cells, RNA polymerase III (also called Pol III) transcribes DNA to synthesize ribosomal 5S rRNA, 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.
How is RNA polymerase activated?
In all species, transcription begins with the binding of the RNA polymerase complex (or holoenzyme) to a special DNA sequence at the beginning of the gene known as the promoter . Activation of the RNA polymerase complex enables transcription initiation, and this is followed by elongation of the transcript.
Is RNA polymerase II a ribozyme?
The RNA polymerase II system is the system that is normally used for the expression of proteins in cells . Numerous constructs have been designed that use this system for the efficient production of proteins and this type of expression system was adopted in early experiments for the expression of ribozymes.
