Assembly of RNA Assembly of RNA polymerase II polymerase II

preinitiation complexpreinitiation complex

Heather DrillingHeather Drilling

RNA Polymerase II (Poll II)RNA Polymerase II (Poll II) is the is the complex responsible for reading the complex responsible for reading the DNA template and creating a DNA template and creating a complementary mRNA copy. In complementary mRNA copy. In order for Poll II to begin this order for Poll II to begin this process, several general process, several general transcription factors must first help transcription factors must first help to position and activate the Poll II to position and activate the Poll II complex. complex.

TFIID, a general transcription TFIID, a general transcription factor, carries a TBP, TATA box-factor, carries a TBP, TATA box-binding protein, to DNA.binding protein, to DNA.

When the TBP portion of the TFIID When the TBP portion of the TFIID molecule attaches to the TATA-molecule attaches to the TATA-box, its shape causes the DNA to box, its shape causes the DNA to bend. bend.

ElongationElongation is the stage of transcription is the stage of transcription in which the Poll II complex creates a in which the Poll II complex creates a complementary strand of mRNA. Once complementary strand of mRNA. Once the entire transcription unit has been the entire transcription unit has been 'copied', the Poll II must release the 'copied', the Poll II must release the newly finished strand of mRNA. The newly finished strand of mRNA. The general transcription factors involved in general transcription factors involved in the process also release during or at the the process also release during or at the end of this stage of transcription. end of this stage of transcription.

Transcription by RNA Polymerase Transcription by RNA Polymerase II can be initiated by sequential II can be initiated by sequential binding of the following:binding of the following:

TBP, which binds to TATA-box DNATBP, which binds to TATA-box DNA TFIIBTFIIB Pol II complex and TFIIFPol II complex and TFIIF TFIIETFIIE TFIIHTFIIH

ReferencesReferences

http://vcell.ndsu.nodak.edu/~christjo/vcell/animhttp://vcell.ndsu.nodak.edu/~christjo/vcell/animationSite/transcription/poll2.htmationSite/transcription/poll2.htm

Lodish, Harvey, et al. Lodish, Harvey, et al. Molecular Cell Molecular Cell BiologyBiology. 5th ed. New York: W. H. . 5th ed. New York: W. H. Freeman, 2004.Freeman, 2004.