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#TFIIH

2 public questions tagged with this topic.

Transcription in Eukaryotes

TFIIH also has kinase activity for phosphorylation of

TFIIH includes CAK subcomplex cyclin activating kinase comprising CDK7 kinase, cyclin H, MAT1 assembly factor stabilizing kinase module. After promoter melting, CDK7 phosphorylates serine five residues within YSPTSPS heptad repeats of RPB1 C-terminal domain, converting initiation complex to early elongation state. Serine5 phosphorylation reduces affinity for Mediator, facilitating promoter escape, and creates binding site for capping enzymes and Set1 methyltransferase depositing H3K4 trimethylation. Later transcription factor P-TEFb containing CDK9 phosphorylates serine two to promote producti

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 6: TFIIH kinase phosphorylates CTD Ser5; Lodish 9th ed., CTD code

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Transcription in Eukaryotes

Which general transcription factor has helicase activity?

Among general Pol II factors, TFIIH alone possesses ATP-dependent DNA helicase activity essential for promoter opening. Complex composed of ten subunits includes XPB ERCC3 translocase with 3' to 5' helicase that pumps downstream DNA toward polymerase, generating torsional stress to melt eleven to fifteen base pairs around transcription start site. XPD ERCC2 helicase participates primarily in nucleotide excision repair. Helicase action requires ATP hydrolysis and is inhibited by triptolide anticancer drug. TFIIH entry after Pol II-TFIIF completes preinitiation complex assembly enabling open com

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 10: TFIIH helicase melts promoter DNA; Alberts 7th ed., General transcription factors TFIIH function

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