title: Protein topography of the 40 S ribosomal subunit from Saccharomyces cerevisiae as shown by chemical cross-linking.
abstract: Protein-protein cross-linking was used to examine the spatial arrangement of proteins within the 40 S ribosomal subunits of Saccharomyces cerevisiae. Purified ribosomal subunits were treated with either 2-iminothiolane or dimethyl 3,3'-dithiobispropionimidate under conditions such that the ribosomal particle was intact and that formation of 40 S subunit dimers was minimized. Proteins were extracted from the treated subunits and fractionated on Sephadex G-150 or by acid-urea-polyacrylamide gel electrophoresis. Cross-linked proteins in these fractions were analyzed by two-dimensional diagonal sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Constituent members of cross-linked pairs were radiolabeled with 125I and identified by two-dimensional gel electrophoresis and comparison with nonradioactive ribosomal protein markers. Forty-two pairs involving 25 of the 32 40 S subunit proteins were identified. Many proteins were detected in several cross-linked dimers. These proteins with multiple cross-links form foci for the construction of a schematic model of the spatial arrangement of proteins within the 40 S subunit.
mesh_terms: D003432:Cross-Linking Reagents / Q000494:pharmacology*; D007096:Imidoesters / Q000494:pharmacology; D046911:Macromolecular Substances; D008970:Molecular Weight; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D003432:Cross-Linking Reagents; D007096:Imidoesters; D046911:Macromolecular Substances; C007471:dimethyl dithiobispropionimidate; C005905:methyl 4-mercaptobutyrimidate