Practice question

Decoding center responsible for monitoring accuracy of codon-anticodon pairing is located in small ribosomal subunit. In bacterial 30S, helices 44, 18 and nucleotides A1492, A1493, G530 of 16S rRNA flip out to inspect minor groove of codon-anticodon duplex, discriminating Watson-Crick pairing via A-minor interactions. Cognate pairing induces domain closure stabilizing GTPase activation of EF-Tu. Large subunit houses peptidyl transferase rather than decoding. Thus fidelity checking segregates to small subunit rRNA, explaining aminoglycoside antibiotics targeting this site to induce misreading. This refined regulation supports accurate ribosomal assembly, quality control and translational fidelity under diverse physiological conditions and growth states.