Work

Differential Recognition of Preproteins by the Purified Cytosolic Domains of the Mitochondrial Import Receptors Tom20, Tom22, and Tom70

Year: 1997

Type: article

Abstract: The preprotein translocase of the outer mitochondrial membrane (Tom) is a multi-subunit complex required for specific recognition and membrane translocation of nuclear-encoded preproteins. We have expressed and purified the cytosolic domains of three postulated import receptors, Tom20, Tom22, and Tom70. Each receptor domain is able to bind mitochondrial preproteins but with different specificity. Tom20 binds both preproteins with N-terminal presequences and preproteins with internal targeting signals; the binding is enhanced by the addition of salt. Tom22 selectively recognizes presequence-carrying preproteins in a salt-sensitive manner. Tom70 preferentially binds preproteins with internal targeting information. A chemically synthesized presequence peptide competes with preproteins for binding to Tom20 and Tom22 but not to Tom70. We conclude that each of the three import receptors binds preproteins independently and by a different mechanism. Both Tom20 and Tom22 function as presequence receptors.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.272.33.20730

Authors: Jan Brix, Klaus Dietmeier, Nikolaus Pfanner

Institution: University of Freiburg

Language: English

Topic: Mitochondrial Function and Pathology

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $3,430

Funder: Deutsche Forschungsgemeinschaft