A proteomics approach to the identification of mammalian mitochondrial small subunit ribosomal proteins.
Mammalian mitochondrial small subunit ribosomal proteins were separated by two-dimensional polyacrylamide gel electrophoresis. The proteins in six individual spots were subjected to in-gel tryptic digestion. Peptides were separated by capillary liquid chromatography, and the sequences of selected peptides were obtained by electrospray tandem mass spectrometry. The peptide sequences obtained were used to screen human expressed sequence tag data bases, and complete consensus cDNAs were assembled. Mammalian mitochondrial small subunit ribosomal proteins from six different classes of ribosomal proteins were identified. Only two of these proteins have significant sequence similarities to ribosomal proteins from prokaryotes. These proteins correspond to Escherichia coli S10 and S14. Homologs of two human mitochondrial proteins not found in prokaryotes were observed in the genomes of Drosophila melanogaster and Caenorhabditis elegans. A homolog of one of these proteins was observed in D. melanogaster but not in C. elegans, while a homolog of the other was present in C. elegans but not in D. melanogaster. A homolog of one of the ribosomal proteins not found in prokaryotes was tentatively identified in the yeast genome. This latter protein is the first reported example of a ribosomal protein that is shared by mitochondrial ribosomes from lower and higher eukaryotes that does not have a homolog in prokaryotes.
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Department of Chemistry and School of Public Health, Environmental Science and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
Burkhart
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Blackburn
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Moseley
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Koc
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Spremulli
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D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans; D002853:Chromatography, Liquid; D016384:Consensus Sequence; D018076:DNA, Complementary; D004330:Drosophila; D029721:Drosophila Proteins; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D008322:Mammals; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D020543:Proteome / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014357:Trypsin
D018076:DNA, Complementary; D029721:Drosophila Proteins; D010446:Peptide Fragments; D020543:Proteome; C489167:RPS21A protein, S cerevisiae; C489168:RPS25 protein, human; C489203:RPS26 protein, human; C489204:RPS26A protein, S cerevisiae; D012269:Ribosomal Proteins; C489202:RpS26 protein, Drosophila; D029701:Saccharomyces cerevisiae Proteins; D014357:Trypsin