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Author Denslow, N. D. ♦ O'Brien, T. W.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword RADIOLOGY AND NUCLEAR MEDICINE ♦ BASIC BIOLOGICAL SCIENCES ♦ RIBOSOMES ♦ IODINATION ♦ STRUCTURAL CHEMICAL ANALYSIS ♦ IODINE 125 ♦ IODINE 131 ♦ ISOTOPE RATIO ♦ MITOCHONDRIA ♦ PEROXIDASES ♦ PROTEINS ♦ BETA DECAY RADIOISOTOPES ♦ BETA-MINUS DECAY RADIOISOTOPES ♦ CELL CONSTITUENTS ♦ CHEMICAL REACTIONS ♦ DAYS LIVING RADIOISOTOPES ♦ ELECTRON CAPTURE RADIOISOTOPES ♦ ENZYMES ♦ HALOGENATION ♦ INTERMEDIATE MASS NUCLEI ♦ IODINE ISOTOPES ♦ ISOTOPES ♦ NUCLEI ♦ ODD-EVEN NUCLEI ♦ ORGANIC COMPOUNDS ♦ ORGANOIDS ♦ OXIDOREDUCTASES ♦ RADIOISOTOPES ♦ Medicine- Unsealed Radionuclides in Diagnostics ♦ Biochemistry- Tracer Techniques
Abstract To assess the relative exposure of individual ribosomal proteins (r-proteins) in the large and small subunits of the bovine mitochondrial ribosome, double label iodination technique was used. Regions of r-proteins exposed in purified ribosomal subunits were labeled with /sup 131/I using the lactoperoxidase-catalyzed iodination system, and additional reactive groups available upon denaturing the r-proteins in urea were labeled with /sup 125/I using the chloramine-T mediated reaction. The ratio of /sup 131/I to /sup 125/I incorporated into individual proteins under these conditions is representative of the degree of exposure for each of the proteins in the subunits. In this manner, the r-proteins have been grouped into 3 classes depending on their degree of exposure: high exposure, intermediate exposure, and essentially buried. While both subunits have a few proteins in the highly exposed group, and a large number of proteins in the intermediate exposure group, only the large ribosomal subunit has an appreciable number of proteins which appear essentially buried. The more buried proteins may serve mainly structural roles, perhaps acting as assembly proteins, since many from this group bind to ribosomal RNA. The more superficially disposed proteins may comprise binding sites for macromolecules that interact with ribosomes during protein synthesis, as well as stabilizing the association of the large and small subribosomal particles.
Educational Use Research
Learning Resource Type Article
Publisher Date 1984-08-10
Publisher Place United States
Journal J. Biol. Chem.
Volume Number 259
Issue Number 15
Organization Univ. of Florida, Gainesville


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