Identification of CBS2 as a mitochondrial protein in Saccharomyces cerevisiae.
The nuclear genome encoded yeast protein CBS2 is required for translational activation of mitochondrial cytochrome b RNA. Genetic studies have shown that the target sequence of the CBS2 protein is the 5' untranslated leader sequence of cytochrome b RNA. Here we report on the intracellular localization of CBS2. CBS2 protein, expressed in Escherichia coli and prepared from inclusion bodies, was used as an antigen to raise a polyclonal rabbit antiserum. Affinity-purified CBS2 antibodies detect a 45 kDa protein in mitochondrial lysates of wild-type cells, which is absent in a strain in which the CBS2 gene has been deleted. The protein is overexpressed in mitochondrial extracts of a transformant carrying the CBS2 gene on a high copy number plasmid, but undetectable in the post-mitochondrial supernatant. Intramitochondrial localization of CBS2 was verified by in vitro import of CBS2 protein that had been synthesized in a reticulocyte lysate programmed with CBS2 mRNA transcribed in vitro. Mitochondrial import of CBS2 is not accompanied by any detectable proteolytic processing.
Michaelis
U
U
Institut für Genetik und Mikrobiologie, Universität München, Federal Republic of Germany.
Rödel
G
G
D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D015153:Blotting, Western; D003001:Cloning, Molecular; D003573:Cytochrome b Group / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic
D003573:Cytochrome b Group; D005656:Fungal Proteins