The outer membrane form of the mitochondrial protein Mcr1 follows a TOM-independent membrane insertion pathway.
The yeast gene MCR1 encodes two isoforms of the mitochondrial NADH-cytochrome b5 reductase. One form is embedded in the outer membrane whereas the other is located in the intermembrane space (IMS). In the present work we investigated the biogenesis of the outer membrane form. We demonstrate that while the IMS form crosses the outer membrane via the translocase of the outer mitochondrial membrane (TOM) complex, the other form is integrated into the outer membrane by a process that does not require any of the known import components at the outer membrane. Thus, the import pathways of the two forms diverge in a stage before the encounter with the TOM complex and their mechanism of biogenesis represents a unique example how to achieve dual localization within one organelle.
Meineke
Birthe
B
Interfaculty Institute for Biochemistry, Hoppe-Seyler-Strasse 4, University of Tübingen, 72076 Tübingen, Germany.
Engl
Gertraud
G
Kemper
Christian
C
Vasiljev-Neumeyer
Andreja
A
Paulitschke
Hanka
H
Rapaport
Doron
D
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D042966:Cytochrome-B(5) Reductase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D051336:Mitochondrial Membranes / Q000201:enzymology*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; C489350:TOM20 protein, S cerevisiae; C489039:TOM70 protein, S cerevisiae; C066555:Tom40 protein, S cerevisiae; D042966:Cytochrome-B(5) Reductase; C470363:MCR1 protein, S cerevisiae