Practice question

48S pre-initiation complex forms after cap recognition by eIF4F and recruitment of 43S pre-initiation complex to mRNA 5' end. eIF4E binds m7G cap, eIF4G bridges to polyA binding protein circularizing mRNA, then 43S joins near cap and scans 5' to 3' direction inspecting codons in P site. Upon locating AUG in favorable Kozak context, perfect codon-anticodon pairing triggers eIF1 release, GTP hydrolysis by eIF2, Pi release, locking stable 48S complex containing mRNA, 40S and initiator tRNA. Subsequent eIF5B mediated 60S joining yields elongation-competent 80S ribosome.