Relationship between the peptide-sensitive channel and the mitochondrial outer membrane protein translocation machinery.
The peptide-sensitive channel (PSC), a cationic channel of the mitochondrial outer membrane, is blocked by synthetic mitochondrial presequences and by nonmitochondrial basic peptides such as dynorphin B(1-13). Both types of peptides are imported into mitochondria. However, the import of dynorphin B(1-13) had to be further characterized since its properties differed from those of the general import pathway used by mitochondrial peptides. Cross-linking experiments with iodinated dynorphin B(1-13) led to the labeling of TOM 40/ISP 42, a component of the protein import machinery of the outer membrane. Accordingly, dynorphin B(1-13) could also be used as a presequence to direct the import of a cytosolic protein into the mitochondria. Pretreatment of intact mitochondria by trypsin removed components capable of discriminating between true mitochondrial presequences and other basic peptides active on the PSC. After proteolysis, both types of peptides appeared to cross the outer membrane through the same pathway. Involvement of the PSC in the translocation complex was shown by immunoprecipitation of the PSC activity by anti-ISP 42 antibodies. Taken together, the present data reinforce the hypothesis that the PSC is the pore responsible for the translocation of protein through the outer membrane.
Juin
P
P
Service de Neurobiologie Physico-Chimique, Centre National de la Recherche Scientifique, Unité Propre de Recherche 9071, Institut de Biologie Physico-Chimique, 13 rue P. et M. Curie, 75005 Paris, France.
Thieffry
M
M
Henry
J P
JP
Vallette
F M
FM
D000818:Animals; D004399:Dynorphins / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure*; D033681:Mitochondrial Membrane Transport Proteins; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism*; D011817:Rabbits; D029701:Saccharomyces cerevisiae Proteins; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
D005656:Fungal Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D010446:Peptide Fragments; D029701:Saccharomyces cerevisiae Proteins; C066555:Tom40 protein, S cerevisiae; C092588:dynorphin B (1-13); C093986:peptide sensitive channel; D004399:Dynorphins; D013762:Tetrahydrofolate Dehydrogenase; D003576:Electron Transport Complex IV; D014357:Trypsin