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

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  • 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 hole 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 similar to 2.1 nm and a height of similar to 7 nm. Tom40 is the key structural element of the TOM core complex.

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    Article (Published)
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    © 1999 Ahting, Thun, Hegerl, Typke, Nargang, Neupert, and Nussberger. This version of this article is open access and can be downloaded and shared. This Creative Commons Attribution-NonCommercial-ShareAlike license lets others remix, tweak, and build upon your work non-commercially, as long as they credit you and license their new creations under the identical terms. The original author(s) and source must be cited.
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    • Ahting, U., Thun, C., Hegerl, R., Typke, D., Nargang, F. E., Neupert, W., & Nussberger, S. (1999). The TOM core complex: the general protein import pore of the outer membrane of mitochondria. The Journal of Cell Biology, 147(5), 959-968. DOI: 10.1083/jcb.147.5.959.