User:Jordan Scott/Sandbox RNA polII: Difference between revisions

RNAP II is responsible for the synthesis of pre-mRNA and snRNs. It is 550 kDa and made of 12 subunits (Rpb1-12) 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 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 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.