Determinants in the presequence of cytochrome b2 for import into mitochondria and for proteolytic processing.
Determinants in a mitochondrial targeting signal for import and processing were analyzed by introducing deletions into the presequence of cytochrome b2. The matrix targeting signal and the signal recognized by the mitochondrial processing peptidase were found to be separate. The signal for import into the matrix is located at the N-terminus within a stretch of 20 amino acid residues that has the potential to form a positively charged, amphipathic alpha-helix. The mitochondrial processing peptidase cleaves after residue 31 and recognizes a short sequence motif around the scissile bond. In the context of a presequence, the cleavage site is accessible for the processing peptidase. At a different location or in a different context, the cleavage site motif is still specifically recognized but processed with lower efficiency. The matrix targeting signal may help to present the cleavage site motif to the mitochondrial processing peptidase.
Klaus
C
C
Institut für Physiologische Chemie der Universität München, München, Germany.
Guiard
B
B
Neupert
W
W
Brunner
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D010450:Endopeptidases / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D042844:L-Lactate Dehydrogenase (Cytochrome); D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015183:Restriction Mapping; D012156:Reticulocytes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D017384:Sequence Deletion; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis / Q000378:metabolism
D017931:DNA Primers; D009838:Oligodeoxyribonucleotides; D011498:Protein Precursors; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D007770:L-Lactate Dehydrogenase; D042844:L-Lactate Dehydrogenase (Cytochrome); D013762:Tetrahydrofolate Dehydrogenase; D010450:Endopeptidases