User:Jordan Scott/Sandbox RNA polII: Difference between revisions
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RNAP II is responsible for the synthesis of pre-mRNA and snRNs. It is 550 kDa and made of 12 subunits that range from 220-10 kDa. The subunits are highly conserved to the point that mammalian subunits can substitute with yeast subunits are there are little to no defects.(B0) There are two large sub units t and 10 smaller subunits, some of which are shared with RNAPs I and III. While RNAP II is capable of transcription by itself it is non-selective of any particular DNA region. However some mutageneis studies have shown that RNAP II may have some role in selectivity. (A) To properly recognize regions upstream of the gene's transcription start site it requires several general transcription factors that are selective for these regions known as promoters and positions RNAP to accurately begin transcription. (B) These GTF's and other | RNAP II is responsible for the synthesis of pre-mRNA and snRNs. It is 550 kDa and made of 12 subunits that range from 220-10 kDa. The subunits are highly conserved to the point that mammalian subunits can substitute with yeast subunits are there are little to no defects.(B0) There are two large sub units t and 10 smaller subunits, some of which are shared with RNAPs I and III. While RNAP II is capable of transcription by itself it is non-selective of any particular DNA region. However some mutageneis studies have shown that RNAP II may have some role in selectivity. (A) To properly recognize regions upstream of the gene's transcription start site it requires several general transcription factors that are selective for these regions known as promoters and positions RNAP to accurately begin transcription. (B) These GTF's and other accessory proteins called SRBs are necessary for accurate transcription and together with thw RNAP II core enzyme form the RNAP holoenzyme. | ||
'''RNA polymerase II''' (RNAP II) is an enzyme that transcribes protein-encoding genes, and it therefore is responsible for the synthesis of mRNA. There are three RNA polymerase enzymes found in eukaryotic nuclei but RNAP II is the most studied. RNAP II is a 550 kDa multi-protein complex that includes 12 subunits. Several transcription factors are used to bind promoters upstream of the start site and are necessary for joining RNAP II and DNA. Bound RNAP II transcribes DNA into a strand of messenger RNA (mRNA). mRNA is a single stranded RNA molecule that is complementary to the template strand of DNA and matches the coding strand. In prokaryotes the transcript is ready for translation, but in eukaryotes post transcriptional modifications are required. The mRNA stand transports genetic information from DNA to the ribosome,where the code will be translated into an amino acid acid sequence to form proteins. | '''RNA polymerase II''' (RNAP II) is an enzyme that transcribes protein-encoding genes, and it therefore is responsible for the synthesis of mRNA. There are three RNA polymerase enzymes found in eukaryotic nuclei but RNAP II is the most studied. RNAP II is a 550 kDa multi-protein complex that includes 12 subunits. Several transcription factors are used to bind promoters upstream of the start site and are necessary for joining RNAP II and DNA. Bound RNAP II transcribes DNA into a strand of messenger RNA (mRNA). mRNA is a single stranded RNA molecule that is complementary to the template strand of DNA and matches the coding strand. In prokaryotes the transcript is ready for translation, but in eukaryotes post transcriptional modifications are required. The mRNA stand transports genetic information from DNA to the ribosome,where the code will be translated into an amino acid acid sequence to form proteins. | ||
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The Discovery and Isolation of RNA Polymerase by Jerard Hurwitz | The Discovery and Isolation of RNA Polymerase by Jerard Hurwitz | ||
RNA Polymerase was first isolated | RNA Polymerase was first discovered and isolated by Jerard Hurwitz in 1960. Prior to this, there was research in the synthesis of RNA. One enzyme known as polynucleotide phosphorylase was first isolated. It was initially thought to synthesize RNA but it was later discovered to degrade RNA. This spurred Hurwitz to search for RNAP using E.coli extracts. In 1960 he showed reproducible RNA synthesis using his extracts and DNA. He published his findings along with three other labs who had also independently worked with RNAP. | ||
After this discovery, Hurwitz, along with John J. Furth, purified the enzyme from the E.coli extracts. The purified enzyme catalyzed RNA in the presence of rNTPs, DNA, and magnesium or manganese ions. | |||
== Structural Components == | == Structural Components == | ||
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Once the <scene name='82/824648/Pic/3'>PIC</scene> is formed, <scene name='82/824648/Rnap_ii/1'>RNAP II</scene> initiates RNA synthesis and produces a short transcript. When RNAP II becomes phosphorylated, it releases some of the GTFs from the complex and moves away from the promoter. TFIID stays bound to the promoter and can reinitiate transcription and | Once the <scene name='82/824648/Pic/3'>PIC</scene> is formed, <scene name='82/824648/Rnap_ii/1'>RNAP II</scene> initiates RNA synthesis and produces a short transcript. When RNAP II becomes phosphorylated, it releases some of the GTFs from the complex and moves away from the promoter. TFIID stays bound to the promoter and can reinitiate transcription and help with successive transcription. The transcription factors are replaced by a new six-protein complex call the Elongator. TFIIF and TFIIH both remain associated with RNAP II during elongation. | ||
