| Autor: |
Stojanovski D; Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Universität Freiburg, D-79104 Freiburg, Germany., Guiard B, Kozjak-Pavlovic V, Pfanner N, Meisinger C |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of cell biology [J Cell Biol] 2007 Dec 03; Vol. 179 (5), pp. 881-93. Date of Electronic Publication: 2007 Nov 26. |
| DOI: |
10.1083/jcb.200706043 |
| Abstrakt: |
The mitochondrial outer membrane contains two preprotein translocases: the general translocase of outer membrane (TOM) and the beta-barrel-specific sorting and assembly machinery (SAM). TOM functions as the central entry gate for nuclear-encoded proteins. The channel-forming Tom40 is a beta-barrel protein, whereas all Tom receptors and small Tom proteins are membrane anchored by a transmembrane alpha-helical segment in their N- or C-terminal portion. Synthesis of Tom precursors takes place in the cytosol, and their import occurs via preexisting TOM complexes. The precursor of Tom40 is then transferred to SAM for membrane insertion and assembly. Unexpectedly, we find that the biogenesis of alpha-helical Tom proteins with a membrane anchor in the C-terminal portion is SAM dependent. Each SAM protein is necessary for efficient membrane integration of the receptor Tom22, whereas assembly of the small Tom proteins depends on Sam37. Thus, the substrate specificity of SAM is not restricted to beta-barrel proteins but also includes the majority of alpha-helical Tom proteins. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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