THE RIBOSOME -- A MACROMOLECULAR MACHINE PAR EXCELLANCE

Joachim Frank
Wadsworth Center and Department of Biomedical Sciences, SUNY Albany

In the past six years, cryo-electron microscopy has provided us with a detailed three-dimensional map of the ribosome. The current resolution is 15 Å, revealing a structure of marvelous complexity. The interaction with tRNA in the course of the elongation cycle takes place in the intersubunit space between the 30S and 50S subunit. Cross-sections of the ribosome indicate the way the intersubunit space is designed to accommodate the L-shaped tRNA molecule and guide it through a succession of binding steps. In addition, we have imaged tRNA bound to the ribosome in defined functional states, and can now describe the positions corresponding to the canonical sites (A, P, and E site) with a high degree of certainty.

J. Frank et al. (1995) A model of protein synthesis based on cryo-electron microscopy of the E. coli ribosome. Nature 376:441-444.