title: Amino-terminal deletions in the presequence of an imported mitochondrial protein block the targeting function and proteolytic cleavage of the presequence at the carboxy terminus.
abstract: Subunit IV of yeast cytochrome oxidase is made in the cytosol with a 25-residue presequence. This presequence targets subunit IV into mitochondria and is removed by a protease in the matrix space. Here we show that removal of as few as 4 amino-terminal residues from the subunit IV presequence (which had been attached to the cytosolic protein dihydrofolate reductase) blocks import of the protein into mitochondria and proteolytic removal of the presequence by the soluble matrix protease. Thus, this protease requires not only an appropriate cleavage site at the carboxy-terminal end of the presequence, but also information at the extreme amino terminus of the presequence.
mesh_terms: D000595:Amino Acid Sequence; D003600:Cytosol / Q000378:metabolism; D004274:DNA, Recombinant; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D010446:Peptide Fragments / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism
chemical_list: D004274:DNA, Recombinant; D010446:Peptide Fragments; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D013762:Tetrahydrofolate Dehydrogenase; D003576:Electron Transport Complex IV; D010447:Peptide Hydrolases