Where is the RNA polymerase II phosphorylated?

8). 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.

Which transcription factor causes the phosphorylation of RNA polymerase 2?

Ser-5 phosphorylation of the RNA polymerase II (Pol II) C-terminal domain by TFIIH kinase has been implicated in critical steps in mRNA synthesis, such as Pol II promoter escape and mRNA 5′-capping.

Why is it useful for RNA polymerase II to be phosphorylated during the transcription cycle?

Hypophosphorylated RNA polymerase II (RNAPIIa) is recruited to promoters and initiates productive transcript elongation once phosphorylated (IIo) in its C-terminal domain (CTD). Cdk7 and Cdk9 phosphorylate the CTD to mediate transition from initiation to elongation, with Cdk9 activity being particularly critical.

What does RNA polymerase II do in transcription?

RNA polymerase II (Pol II) transcribes all eukaryotic protein-coding genes and most non-coding RNA genes. The final step of transcription is termination, which leads to the release of Pol II and RNA from the DNA template through a poorly defined mechanism.

What are dynamic phosphorylation patterns of RNA polymerase II CTD?

Dynamic phosphorylation patterns of serine residues in CTD during gene transcription coordinate the recruitment of factors to the elongating RNAPII and to the nascent transcript. Recent studies identified threonine 4 and tyrosine 1 as new CTD modifications and thereby expanded the “CTD code”.

When does phosphorylation of the CTD take place?

Phosphorylation of the CTD occurs soon after initiation and is necessary for capping enzyme recruitment. Other RNA-processing factors bind to both phosphorylated and unphosphorylated CTD and act much later during transcription.

Which is the C terminal domain of RNA polymerase II?

The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) contains a series of YSPTSPS heptad repeats that are multiply-phosphorylated during the eukaryotic transcription cycle.

Can a RNAPII be a phosphorylated CTD?

RNAPII can exist in a form with a highly phosphorylated CTD (subunit II 0; RNAPII0) and a form with a nonphosphorylated CTD (subunit II a; RNAPIIA) (for a review, see Dahmus and Dynan 1992 ).