A researcher adds puromycin to an in vitro translation system. Translation stops and incomplete polypeptides are released attached to the drug. The structural feature of puromycin responsible for this action is:

• A Its resemblance to the 3' end of aminoacyl-tRNA bearing tyrosine ✓
• B Its ability to intercalate between bases of the mRNA codons
• C Its mimicry of the release factor RF1 shape
• D Its irreversible binding to the E site of the ribosome

Explanation

Puromycin structurally resembles the aminoacyl-adenosine portion of a charged tRNA, specifically resembling tyrosyl-tRNA. It enters the A site, accepts the growing peptide chain via its free amino group, and because it lacks the ester linkage needed for further peptide bond formation, the peptidyl-puromycin product dissociates, terminating translation prematurely in both prokaryotes and eukaryotes. It does not intercalate into mRNA, mimic release factors, or bind the E site irreversibly.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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