The preprotein translocation channel of the outer membrane of mitochondria.
The preprotein translocase of the outer membrane of mitochondria (TOM complex) facilitates the recognition, insertion, and translocation of nuclear-encoded mitochondrial preproteins. We have purified the TOM complex from Neurospora crassa and analyzed its composition and functional properties. The TOM complex contains a cation-selective high-conductance channel. Upon reconstitution into liposomes, it mediates integration of proteins into and translocation across the lipid bilayer. TOM complex particles have a diameter of about 138 A, as revealed by electron microscopy and image analysis; they contain two or three centers of stain-filled openings, which we interpret as pores with an apparent diameter of about 20 A. We conclude that the structure reported here represents the protein-conducting channel of the mitochondrial outer membrane.
Künkele
K P
KP
Institut für Physiologische Chemie, Physikalische Biochemie, und Zellbiologie der Universität München, Germany.
Heins
S
S
Dembowski
M
M
Nargang
F E
FE
Benz
R
R
Thieffry
M
M
Walz
J
J
Lill
R
R
Nussberger
S
S
Neupert
W
W
D015060:1,2-Dipalmitoylphosphatidylcholine; D001692:Biological Transport; D002412:Cations; D004553:Electric Conductivity; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000737:chemistry; D015640:Ion Channel Gating; D007473:Ion Channels; D008051:Lipid Bilayers; D008190:Lyases / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure; D008928:Mitochondria / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D009492:Neurospora crassa / Q000737:chemistry*; D011498:Protein Precursors / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000378:metabolism; D011510:Proteolipids
D002412:Cations; D005656:Fungal Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; D011510:Proteolipids; C020485:proteoliposomes; D015060:1,2-Dipalmitoylphosphatidylcholine; D008190:Lyases; C031581:cytochrome C synthetase