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The Tim9p–Tim10p complex binds to the transmembrane domains of the ADP/ATP carrier
Author(s) -
Curran Sean P.,
Leuenberger Danielle,
Oppliger Wolfgang,
Koehler Carla M.
Publication year - 2002
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/21.5.942
Subject(s) - intermembrane space , mitochondrial intermembrane space , biology , biochemistry , cysteine , translocase , chaperone (clinical) , atp–adp translocase , mitochondrial carrier , transmembrane protein , transmembrane domain , translocase of the outer membrane , zinc finger , biophysics , mitochondrial membrane transport protein , plasma protein binding , inner mitochondrial membrane , mitochondrion , amino acid , bacterial outer membrane , enzyme , medicine , chromosomal translocation , receptor , escherichia coli , pathology , transcription factor , gene
The soluble Tim9p–Tim10p (Tim, translocase of inner membrane) complex of the mitochondrial intermembrane space mediates the import of the carrier proteins and is a component of the TIM22 import system. The mechanism by which the Tim9p–Tim10p complex assembles and binds the carriers is not well understood, but previous studies have proposed that the conserved cysteine residues in the ‘twin CX 3 C’ motif coordinate zinc and potentially generate a zinc‐finger‐like structure that binds to the matrix loops of the carrier proteins. Here we have purified the native and recombinant Tim9p–Tim10p complex, and show that both complexes resemble each other and consist of three Tim9p and three Tim10p. Results from inductively coupled plasma–mass spectrometry studies failed to detect zinc in the Tim9p–Tim10p complex. Instead, the cysteine residues seemingly formed disulfide linkages. The Tim9p–Tim10p complex bound specifically to the transmembrane domains of the ADP/ATP carrier, but had no affinity for Tim23p, an inner membrane protein that is inserted via the TIM22 complex. The chaperone‐like Tim9p–Tim10p complex thus may prevent aggregation of the unfolded carrier proteins in the aqueous intermembrane space.