RNA polymerase II catalyzes the transcription of DNA into precursors of mRNA, snRNA, and microRNA. The initiation of transcription involves transcription factors assembling with RNA polymerase II at the promoter region of DNA. Termination of transcription does not involve specific signals, and RNA polymerase II can continue transcribing thousands of base pairs past the gene end. However, the transcript is cleaved before transcription is fully completed. RNA polymerase II has 10-12 subunits that perform various functions like maintaining contact with DNA and regulating polymerase function.

1. RNA POL II
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2. RNA POL II
Catalyzes the
transcription of DNA to
synthesize precursors
of mRNA and most
snRNA and microRNA.
RNA POLYMERASE II
TRANSCRIPTION INITIATION
initiation factors
[transcription factor (TF) IIB,
TFIID, TFIIE, TFIIF, and TFIIH]
assemble on promoter
(TATA box) DNA with pol II
(transcription initiation
complex), creating a large
multi protein–DNA complex
that supports accurate
initiation.
RNA POLYMERASE II
TRANSCRIPTION TERMINATION
Pol II lack any specific signals or
sequences that diret RNA Pol II
to terminate at specific
locations. RNA Pol II can
continue to transcribe RNA
anywhere from a few bp to
thousands of bp past the actual
end of the gene. However, the
transcript is cleaved at an
internal site before RNA
Polymerase II finishes
transcribing (upstream AAUAAA
sequence and a downstream GU-
rich sequence separated by
about 40-60 nucleotides in the
emerging RNA)
For his work on the
mechanisms of ‘eukaryotic
transcription’, Roger D.
Kornberg
received the Nobel Prize in
Chemistry in 2006.

3. NO SUBUNIT FUNCTION
1 DNA-directed RNA polymerase II subunit RPB1 Forms the DNA binding domain. (CTD)- capping, splicing, and 3′
processing of mRNA precursors
2 RPB2 (POLR2B) Maintains contact
3 RPB3 (POLR2C) a core subassembly
4 RNA polymerase II subunit B4 (RPB4) Stress protective role
5 RPB5 Strongly interacts with RPB1, RPB3, and RPB6
6 RPB6 (POLR2F) Stabilizes the transcribing Pol on the DNA template
7 RPB7 Regulating polymerase function
8 RPB8 (POLR2H) Interacts with subunits RPB1-3, 5&7
9 RPB9 The groove formation
10 RPB10 Interacts with RPB1-3 and 5&strongly with RPB3
11 RPB11 Composed of three subunits
12 RPB12 Interacts with RPB3 is RPB12
THE PURIFIED ENZYME HAS TYPICALLY 10-12 SUBUNITS

4. SUBUNITS of RNA POL II
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