During eukaryotic translation, the 80S ribosome dissociates after termination. Eukaryotic release factor eRF1 recognizes all three stop codons (UAA, UAG, UGA). eRF3 is a GTPase. After peptide release, the ribosome recycling factor equivalent in eukaryotes is ABCE1. Which post-termination event does ABCE1 catalyze using ATP hydrolysis?

• A Dissociation of the mRNA from the 40S subunit after ribosome splitting
• B Deacylated tRNA ejection from the P-site before ribosome splitting
• C eIF3 and eIF1 recruitment to the 40S subunit to prevent premature re-association
• D Ribosome splitting into 40S and 60S subunits to allow re-use ✓

Explanation

After peptide release (catalyzed by eRF1 in the A-site), the 80S ribosome remains stalled on the mRNA at the stop codon with deacylated tRNA in the P-site. ABCE1 (an ATP-binding cassette protein) is the ribosome-splitting ATPase in eukaryotes. ABCE1 uses ATP hydrolysis to actively separate (split) the 60S subunit from the 40S-mRNA-tRNA complex, analogous to the bacterial ribosome recycling factor (RRF) + EF-G action. The resulting 40S-mRNA complex then requires Dom34/Hbs1 or other factors for mRNA disengagement. eIF3 and eIF1 join after splitting to prevent 60S re-association. This ribosome recycling step is essential for maintaining the pool of free ribosomal subunits; ABCE1 mutations or inhibition severely impair global translation.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.