Ribosomal crystalline arrays of large subunits from Escherichia coli.

Crystalline sheets of the 50S ribosomal subunits of Escherichia coli have been formed in vitro. Electron micrographs of these arrays diffract to 35-angstrom resolution. The lattice parameters of the crystals are a = 330 +/- 20 angstroms, b = 330 +/- 30 angstroms, and alpha = 123 degrees +/- 5 degrees, and the space group is most likely p21. These arrays of ribosomal subunits are sufficiently ordered to resolve such known features of the large ribosomal subunit as the L7/L12 stalk and the central protuberance.