5.5 Å Structure of the Eukaryotic Ribosome

Protein biosynthesis, the translation of the genetic code into
polypeptides, occurs on ribonucleoprotein particles called
ribosomes. Although X-ray structures of bacterial ribosomes are
available, high-resolution structures of eukaryotic 80S ribosomes
are lacking. Using cryo-electron microscopy and single-particle
reconstruction we have determined the structure of a translating
plant (Triticum aestivum) 80S ribosome at 5.5 Å resolution. This
map, together with a 6.1 Å map of a Saccharomyces cerevisiae 80S
ribosome, has enabled us to model ~98 % of the rRNA and localize
74/80 (92.5 %) of the ribosomal proteins, encompassing 11
archaeal/eukaryote-specific small subunit proteins as well as the
complete complement of the ribosomal proteins of the eukaryotic
large subunit. Near-complete atomic models of the 80S ribosome
provide insights into the structure, function and evolution of the
eukaryotic translational apparatus.