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The TOM core complex: the general protein import pore of the outer membrane of mitochondria.

Ahting U, Thun C, Hegerl R, Typke D, Nargang FE, Neupert W, Nussberger S - J. Cell Biol. (1999)

Bottom Line: It forms a double ring structure that, in contrast to the holo complex, lacks the third density seen in the latter particles.Three-dimensional reconstruction by electron tomography exhibits two open pores traversing the complex with a diameter of approximately 2.1 nm and a height of approximately 7 nm.Tom40 is the key structural element of the TOM core complex.

View Article: PubMed Central - PubMed

Affiliation: Institut für Physiologische Chemie der Universität München, D-80336 München, Germany.

ABSTRACT
Translocation of nuclear-encoded preproteins across the outer membrane of mitochondria is mediated by the multicomponent transmembrane TOM complex. We have isolated the TOM core complex of Neurospora crassa by removing the receptors Tom70 and Tom20 from the isolated TOM holo complex by treatment with the detergent dodecyl maltoside. It consists of Tom40, Tom22, and the small Tom components, Tom6 and Tom7. This core complex was also purified directly from mitochondria after solubilization with dodecyl maltoside. The TOM core complex has the characteristics of the general insertion pore; it contains high-conductance channels and binds preprotein in a targeting sequence-dependent manner. It forms a double ring structure that, in contrast to the holo complex, lacks the third density seen in the latter particles. Three-dimensional reconstruction by electron tomography exhibits two open pores traversing the complex with a diameter of approximately 2.1 nm and a height of approximately 7 nm. Tom40 is the key structural element of the TOM core complex.

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Native gel electrophoresis of the TOM complexes. A, Native PAGE (Phast) of purified TOM holo complex and isolated core complex. B, Blue native gel electrophoresis of TOM holo complex and core complex. Gels were stained with Coomassie. Marker proteins: Thy, thyroglobulin (669 kD); ApoF, apoferritin (443 kD); ADH, alcohol dehydrogenase (155 kD); Alb, albumin (66 kD).
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Figure 4: Native gel electrophoresis of the TOM complexes. A, Native PAGE (Phast) of purified TOM holo complex and isolated core complex. B, Blue native gel electrophoresis of TOM holo complex and core complex. Gels were stained with Coomassie. Marker proteins: Thy, thyroglobulin (669 kD); ApoF, apoferritin (443 kD); ADH, alcohol dehydrogenase (155 kD); Alb, albumin (66 kD).

Mentions: To further confirm the tight association of Tom40, Tom22, and the smaller Tom proteins in a defined subcomplex, purified TOM holo complex and TOM core complex were examined by native PAGE. Single high molecular weight bands were observed upon staining with Coomassie brilliant blue (Fig. 4 A). The different migration behavior of the complexes is due to the different detergents. The holo complex was solubilized in digitonin whereas the core complex has been purified in DDM.


The TOM core complex: the general protein import pore of the outer membrane of mitochondria.

Ahting U, Thun C, Hegerl R, Typke D, Nargang FE, Neupert W, Nussberger S - J. Cell Biol. (1999)

Native gel electrophoresis of the TOM complexes. A, Native PAGE (Phast) of purified TOM holo complex and isolated core complex. B, Blue native gel electrophoresis of TOM holo complex and core complex. Gels were stained with Coomassie. Marker proteins: Thy, thyroglobulin (669 kD); ApoF, apoferritin (443 kD); ADH, alcohol dehydrogenase (155 kD); Alb, albumin (66 kD).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169338&req=5

Figure 4: Native gel electrophoresis of the TOM complexes. A, Native PAGE (Phast) of purified TOM holo complex and isolated core complex. B, Blue native gel electrophoresis of TOM holo complex and core complex. Gels were stained with Coomassie. Marker proteins: Thy, thyroglobulin (669 kD); ApoF, apoferritin (443 kD); ADH, alcohol dehydrogenase (155 kD); Alb, albumin (66 kD).
Mentions: To further confirm the tight association of Tom40, Tom22, and the smaller Tom proteins in a defined subcomplex, purified TOM holo complex and TOM core complex were examined by native PAGE. Single high molecular weight bands were observed upon staining with Coomassie brilliant blue (Fig. 4 A). The different migration behavior of the complexes is due to the different detergents. The holo complex was solubilized in digitonin whereas the core complex has been purified in DDM.

Bottom Line: It forms a double ring structure that, in contrast to the holo complex, lacks the third density seen in the latter particles.Three-dimensional reconstruction by electron tomography exhibits two open pores traversing the complex with a diameter of approximately 2.1 nm and a height of approximately 7 nm.Tom40 is the key structural element of the TOM core complex.

View Article: PubMed Central - PubMed

Affiliation: Institut für Physiologische Chemie der Universität München, D-80336 München, Germany.

ABSTRACT
Translocation of nuclear-encoded preproteins across the outer membrane of mitochondria is mediated by the multicomponent transmembrane TOM complex. We have isolated the TOM core complex of Neurospora crassa by removing the receptors Tom70 and Tom20 from the isolated TOM holo complex by treatment with the detergent dodecyl maltoside. It consists of Tom40, Tom22, and the small Tom components, Tom6 and Tom7. This core complex was also purified directly from mitochondria after solubilization with dodecyl maltoside. The TOM core complex has the characteristics of the general insertion pore; it contains high-conductance channels and binds preprotein in a targeting sequence-dependent manner. It forms a double ring structure that, in contrast to the holo complex, lacks the third density seen in the latter particles. Three-dimensional reconstruction by electron tomography exhibits two open pores traversing the complex with a diameter of approximately 2.1 nm and a height of approximately 7 nm. Tom40 is the key structural element of the TOM core complex.

Show MeSH