Question

1. Capping factors catalyze the addition of the unique 5' structure on mRNAs. They are physically in position near the new 5' end of transcripts to perform this function because of what?

A. TFIID binds to the TATA box

B. TFIID binds to the -35 box

C. TFIID phosphorylates the polymerase C termina domain(CTD)

D. TFIIH bind to the TATA box

E. TFIIH binds to the -35 box

F. TFIIH phosphorylates the polymerase C terminal domain(CTD)

Answer 1

Capping factors catalyze the addition of the unique 5' structure on mRNAs. They are physically in position near the new 5' end of transcripts to perform this function because of what?

F. TFIIH phosphorylates the polymerase C terminal domain(CTD)

Explanation- The CTD is required for the stimulation of transcription in response to certain enhancers and activators

CTD undergoes a cycle of extensive phosphorylation and dephosphorylation that accompanies the transcription cycle. Several kinases can phosphorylate the CTD, including cdk7, a component of the basal transcription factor TFIIH.

So Pol II-specific capping of nascent transcripts in vivo is enhanced by recruitment of the capping enzymes to the CTD and and capping is co-ordinated with TFIIH phosphorylation of CTD.

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