During the process of transcription, the RNA polymerase II carboxy terminal doma
ID: 164094 • Letter: D
Question
During the process of transcription, the RNA polymerase II carboxy terminal domain (CTD) is phosphorylated by specific kinases on serine amino acids in a ‘heptad repeat’. Specific phosphatases can remove these phosphate groups. Which of the following phosphatases do you think would be most effective in immediately stopping any new transcription when added to an in vitro transcription reaction (a test tube reaction containing RNA polymerase II, a DNA template, rNTPs and all of the general transcription factors)? Explain.
a. phosphatase specific for Ser-2
b. phosphatase specific for Ser-5
Explanation / Answer
Answer:
A multiple heptad repeats were found in the Carboxy terminal domain (CTD) of the RNA Polymerase-II in Vertebrates, while participate in the trancription and post trancription events. During trancription it participate in elongation and termination, whereas in post transcriptional events it participate in the processing of the nascent DNA. It also particpates in phosphorylation during post translational events. Carboxy terminal domain (CTD) contain consensus "heptad repeat" ( Tyr1–Ser2–Pro3–Thr4–Ser5–Pro6–Ser7).The phosphorylation is due to presence of the Ser-2 and Ser-5, which are cofunctional. Both are essential and partcipate in phosphorylation.
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