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#CTD

3 public questions tagged with this topic.

Transcription in Eukaryotes

Phosphorylation of Ser2 in CTD is associated with

During transition to productive elongation, CDK9 cyclin-dependent kinase of P-TEFb complex and later CDK12 phosphorylate serine two of CTD heptad repeats YSPTSPS, creating high density pattern near three prime end of gene body. Serine2-P CTD recruits histone chaperone FACT, Spt6, chromatin modifier Set2 responsible for H3K36 trimethylation, and cleavage and polyadenylation factors CPSF and CstF for messenger RNA three prime end formation. Exchange from serine five to serine two ensures temporal coupling of elongation, chromatin restoration, and termination. Phosphatase Fcp1 recycles polymerase after termination releasing from DNA.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 10: Ser2-P marks elongation; J Biol Chem, CTD Ser2 phosphorylation elongation

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Transcription in Eukaryotes

Phosphorylation of Ser5 in CTD is associated with

Phosphorylation of CTD heptad serine five by TFIIH CDK7 occurs early during transcription, peaking within fifty base pairs downstream of promoter. Serine5-phosphorylated CTD serves as landing pad for capping enzyme complex containing RNA triphosphatase, guanylyltransferase, N7-methyltransferase activities, stimulating cotranscriptional cap addition when transcript reaches twenty to thirty nucleotides. Marker also recruits early spliceosome components and H3K4 methyltransferase Set1 complex via interaction with Paf1 elongation complex. Phosphatases Ssu72 and Rtr1 later dephosphorylate serine five as serine two phosphorylation rises during elongation progression toward gene end.

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 6: Ser5-P associated with initiation and promoter escape; PLoS Biology CTD phosphorylation dynamics

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Transcription in Eukaryotes

Heptapeptide repeat in CTD of RNA pol II is

Largest subunit of eukaryotic RNA polymerase II possesses unique C-terminal domain extension absent in Pol I and Pol III. Domain consists of tandem repeats of conserved heptapeptide Tyr-Ser-Pro-Thr-Ser-Pro-Ser, written YSPTSPS, twenty-six copies in yeast Saccharomyces cerevisiae and fifty-two copies in mammals providing extended tail. Conserved tyrosine one, serines two, five, seven can be phosphorylated, threonine four phosphorylated, prolines three and six isomerized, lysine seven acetylated, creating combinatorial CTD code read by processing factors coordinating transcription with capping, splicing, and termination.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 10: Heptapeptide repeat YSPTSPS in CTD; Cell Biology of CTD code

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