What is the role of initiation factors in eukaryotic translation initiation?

• A. They degrade ribosomal subunits
• B. They synthesize tRNA
• C. They assist in ribosome recruitment and start codon recognition
• D. They terminate translation

Answer: (C)

Initiation factors coordinate the first steps of protein synthesis in eukaryotes by getting the ribosome onto the mRNA and ensuring the start site is identified correctly. They assemble the 40S subunit with the initiator tRNA in a GTP-dependent complex and recruit this pre-initiation complex to the mRNA via the cap-binding machinery (eIF4E and partners). The helicase activity helps unwind secondary structures so the ribosome can scan the 5′ end until a favorable start codon context is found. Once the start codon is recognized, GTP hydrolysis triggers rearrangements that allow the 60S subunit to join and the initiation factors to depart, starting elongation. So, their central role is to assist in ribosome recruitment and start codon recognition. They do not degrade ribosomal subunits, synthesize tRNA, or terminate translation.