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Eduncle posted an MCQ
December 30, 2019 • 15:49 pm 0 points
  • CSIR NET
  • Life Sciences

During translation in prokaryotes, when ribosomes reach the termination codon, the termination codon is recognized by the class I release factors (RF1 and RF2) leading to the release of the polypeptide. A second class II release factor (RF3) facilitates the termination process. Which of the following statements regarding the mechanism of action of the release factors is INCORRECT ?

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    Eduncle Best Answer

    Free RF3 binds GDP very strongly, and the spontaneous dissociation of the guanine nucleotide is slow, implying that cytoplasmic RF3 is in the GDP, rather than the GTP, conformation. When RF3·GDP associates with a ribosome in complex with a class 1 RF, the GDP on RF3 can rapidly dissociate and be exchanged for GTP. RF3 in the GTP conformation has a high affinity for the ribosome in the absence of a class 1 RF, and its binding destabilizes that of RF1 or RF2. The formation of RF3· GTP therefore leads to rapid dissociation of RF1 or RF2 from the ribosome. Subsequent hydrolysis of GTP on RF3 leads to its fast dissociation in the GDP conformation, the normal free state of the factor

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