Practice question

Eukaryotic cytosolic initiator tRNA carries unformylated methionine, distinguishing cytosolic machinery from bacterial and mitochondrial systems. Met-tRNAiMet is delivered by ternary complex eIF2 GTP Met-tRNAi to 40S P site within 43S pre-initiation complex during scanning initiation. Methionine remains first amino acid but often removed co-translationally by methionine aminopeptidases depending on second residue. Lack of formylation reflects distinct eIF2 recognition and insensitivity to initiator specific antibiotics, yet preserves N to C synthesis polarity and requirement for AUG start codon fidelity guided by Kozak context.