In extracto cryo-EM reveals eEF2 as a major hibernation factor on 60S and 80S particles.

eEF2 is the dominant hibernation factor, binding to over 95% of 80S ribosomes and 60S subunits in mammalian cells, revealing a key role in cellular stress responses.

• Why it matters: Understanding how ribosomes enter hibernation is crucial for insights into translational regulation during stress, yet detailed native structures of these complexes have been elusive.
• What they did: Using in extracto cryo-EM, the study achieved ~2.2 Å resolution maps of mammalian translational machinery, identifying eEF2 and other factors associated with hibernating ribosomes in cellular lysates.
• The result: This work demonstrates the power of in extracto cryo-EM to uncover native cellular complexes at near-atomic detail, advancing knowledge of ribosomal hibernation mechanisms and cellular stress adaptation.