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The three modules of ADP/ATP carrier cooperate in receptor recruitment and translocation into mitochondria
Author(s) -
Wiedemann Nils,
Pfanner Nikolaus,
Ryan Michael T.
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.5.951
Subject(s) - biology , translocase of the inner membrane , microbiology and biotechnology , inner membrane , mitochondrion , inner mitochondrial membrane , bacterial outer membrane , transport protein , receptor , chromosomal translocation , translocase of the outer membrane , mitochondrial membrane transport protein , atp synthase , biophysics , biochemistry , enzyme , escherichia coli , gene
The ADP/ATP carrier (AAC) is a major representative of mitochondrial preproteins lacking an N‐terminal presequence. AAC contains targeting information in each of its three modules, which has led to a search for the dominant targeting region. An alternative, not yet tested model would be that several distinct targeting signals function simultaneously in import of the preprotein. We report that the three AAC modules cooperate in binding to the receptor Tom70 such that three Tom70 dimers are recruited to one preprotein. The modules are transferred to the import pore in a stepwise manner and cooperate again in the accumulation of AAC in the general import pore complex. AAC can cross the outer membrane with an internal segment first, i.e. in a loop formation. Each module of AAC is required for dimerization in the inner membrane. We propose a new concept for import of the hydrophobic carrier proteins into mitochondria where multiple signals cooperate in receptor recruitment, outer membrane translocation via loop formation and assembly in the inner membrane.