Practice question

RNase D functions with strict 3' to 5' polarity, removing nucleotides from 3' end towards 5' direction. After RNase P and RNase E liberate pre-tRNA with extended 3' trailer, RNase D binds exposed 3' single strand and sequentially hydrolyzes phosphodiester bonds, advancing backward. Strong secondary structure and mature CCA end block further degradation, defining stopping point. This orientation protects upstream coding regions while achieving terminal precision needed for CCA addition and aminoacylation, maintaining tRNA integrity and turnover control. This refined regulation supports accurate ribosomal assembly, quality control and translational fidelity under diverse physiological conditions and growth states.