Mitochondrial transport of mitoribosomal proteins, YmL8 and YmL20, in Saccharomyces cerevisiae.
Two mitochondrial ribosomal (mitoribosomal) proteins, YmL8 and YmL20, of the yeast Saccharomyces cerevisiae and their derivatives were synthesized in vitro and their transport into isolated yeast mitochondria was examined. Of the two proteins, YmL20 possesses an N-terminal presequence of 18 amino acid residues, while YmL8 has no such presequence. Both proteins were found to be transported into isolated mitochondria in an energy-dependent manner. Furthermore, YmL20 protein without its N-terminal presequence was also transported, despite the fact that the presequence alone was capable of transporting a fused passenger protein, Chinese hamster dihydrofolate reductase (DHFR). Therefore, YmL20 protein appears to possess redundant transport signals in its structure. Similarly, YmL8 derivatives lacking either 40 or 86 amino acid residues from the N-terminus and/or 52 amino acid residues from the C-terminus were transported. In addition, the N-terminal segment of this protein was capable of transporting Chinese hamster DHFR into mitochondria, while its C-terminal segment was not. Thus, YmL8 protein also appears to possess two or more transport signals in its structure. Perhaps the presence of many basic amino acid residues in these proteins might, at least partly, contribute to their mitochondrial transport.
Graduate School of Science and Technology, Faculty of Science, Kobe University, Japan.
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Matsushita
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Isono
D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D006224:Cricetinae; D004271:DNA, Fungal / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism
D004271:DNA, Fungal; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; C081730:mitochondrial ribosomal protein YmL20; C081729:mitochondrial ribosomal protein YmL8; D013762:Tetrahydrofolate Dehydrogenase