In eukaryotic translation, the cap-dependent initiation complex assembles at the 5' m7G cap. The critical eIF (eukaryotic initiation factor) that scans the mRNA in the 5' to 3' direction and recognises the Kozak consensus sequence around the AUG start codon is:

• A eIF4E (cap-binding protein)
• B eIF4G (scaffold protein)
• C eIF2 (ternary complex carrier)
• D eIF4A (RNA helicase) ✓

Explanation

eIF4A is an ATP-dependent RNA helicase that unwinds secondary structures in the 5' UTR, allowing the 43S pre-initiation complex (40S + eIF2-GTP-Met-tRNAi + other factors) to scan along the mRNA until it encounters the AUG start codon in the Kozak context. eIF4E binds the m7G cap and is the rate-limiting initiation factor (target of rapamycin/mTOR regulation); eIF4G is the scaffold that bridges eIF4E, eIF4A, and the poly-A binding protein; eIF2 delivers the initiator methionyl-tRNA to the ribosome. eIF4F complex = eIF4E + eIF4G + eIF4A.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.