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          Institute: MPI für Biophysik     Collection: Abt. Strukturbiologie     Display Documents



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ID: 12094.0, MPI für Biophysik / Abt. Strukturbiologie
Protein translocase of the outer mitochondrial membrane: role of import receptors in the structural organization of the TOM complex
Authors:Model, K.; Prinz, T.; Ruiz, T.; Radermacher, M.; Krimmer, T.; Kühlbrandt, W.; Pfanner, N.; Meisinger, C.
Date of Publication (YYYY-MM-DD):2002
Title of Journal:Journal of Molecular Biology
Volume:316
Issue / Number:3
Start Page:657
End Page:666
Review Status:not specified
Audience:Experts Only
Abstract / Description:The mitochondrial outer membrane contains a multi-subunit machinery responsible for the specific recognition and translocation of precursor proteins. This translocase of the outer membrane (TOM) consists of three receptor proteins, Tom20, Tom22 and Tom70, the channel protein Tom40, and several small Tom proteins. Single-particle electron microscopy analysis of the Neurospora TOM complex has led to different views with two or three stain-filled centers resembling channels. Based on biochemical and electron microscopy studies of the TOM complex isolated from yeast mitochondria, we have discovered the molecular reason for the different number of channel-like structures. The TOM complex from wild-type yeast contains up to three stain-filled centers, while from a mutant yeast selectively lacking Tom20, the TOM complex particles contain only two channel-like structures. From mutant mitochondria lacking Tom22, native electrophoresis separates an approximately 80 kDa subcomplex that consists of Tom40 only and is functional for accumulation of a precursor protein. We conclude that while Tom40 forms the import channels, the two receptors Tom22 and Tom20 are required for the organization of Tom40 dimers into larger TOM structures. Copyright 2002 Elsevier Science Ltd.
Free Keywords:Fungal Proteins/me [Metabolism]; Gene Deletion; *Intracellular Membranes/en [Enzymology]; Membrane Proteins/ch [Chemistry]; Membrane Proteins/ge [Genetics]; *Membrane Proteins/me [Metabolism]; Membrane Proteins/ul [Ultrastructure]; Membrane Transport Proteins/ch [Chemistry]; Membrane Transport Proteins/ge [Genetics]; *Membrane Transport Proteins/me [Metabolism]; Membrane Transport Proteins/ul [Ultrastructure]; Microscopy, Electron; *Mitochondria/en [Enzymology]; Mitochondria/ge [Genetics]; Mitochondrial Proteins/ch [Chemistry]; Mitochondrial Proteins/ge [Genetics]; *Mitochondrial Proteins/me [Metabolism]; Mitochondrial Proteins/ul [Ultrastructure]; Neurospora/en [Enzymology]; Protein Precursors/me [Metabolism]; Protein Structure, Quaternary; Protein Transport; *Saccharomyces cerevisiae/cy [Cytology]; *Saccharomyces cerevisiae/en [Enzymology]; Saccharomyces cerevisiae/ge [Genetics]; Saccharomyces cerevisiae Proteins/ch [Chemistry]; Saccharomyces cerevisiae Proteins/ge [Genetics]; *Saccharomyces cerevisiae Proteins/me [Metabolism]; Saccharomyces cerevisiae Proteins/ul [Ultrastructure]; Support, Non-U.S. Gov't; Support, U.S. Gov't, Non-P.H.S.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Biophysik/Abteilung Strukturbiologie
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