title: The tetrameric form of ribosomal protein L7/L12 from Escherichia coli.
abstract: A tetrameric form of the ribosomal protein L7/L12 has been prepared and its structure studied by using hydrodynamic methods, photon correlation spectroscopy, and small angle x-ray scattering. The tetrameric nature of the protein preparation is confirmed by three independent determinations of its molecular weight, with analysis of accurate sedimentation equilibrium data giving the most reliable estimate. The species has a Stokes radius of 4.0 +/- 0.1 nm and an absolute frictional ratio of 1.7. Taken together, the hydrodynamic measurements suggest the possibility of a flat structure, and this is consistent with the x-ray scattering results. The molecule has a radius of gyration of 3.6 +/- 0.05 nm and a maximum dimension of 11-12 nm. A geometric model consisting of four elongated monomers, arranged in a plane, is proposed.
authors.affiliation: Institut für Kristallographie, Freie Universität Berlin, Federal Republic of Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Georgalis
authors.forename: J
authors.initials: J
authors.lastname: Dijk
authors.forename: H
authors.initials: H
authors.lastname: Labischinski
authors.forename: P R
authors.initials: PR
authors.lastname: Wills
mesh_terms: D001426:Bacterial Proteins; D004058:Diffusion; D004926:Escherichia coli / Q000032:analysis*; D046911:Macromolecular Substances; D008970:Molecular Weight; D011487:Protein Conformation; D012269:Ribosomal Proteins; D012542:Scattering, Radiation; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014461:Ultracentrifugation; D014783:Viscosity
chemical_list: D001426:Bacterial Proteins; D046911:Macromolecular Substances; D012269:Ribosomal Proteins; D012996:Solutions; C016700:ribosomal protein L7-L12