Carrier protein import into mitochondria mediated by the intermembrane proteins Tim10/Mrs11 and Tim12/Mrs5.

Import of nuclear-encoded precursor proteins into mitochondria and their subsequent sorting into mitochondrial subcompartments is mediated by translocase enzymes in the mitochondrial outer and inner membranes. Precursor proteins carrying amino-terminal targeting signals are translocated into the matrix by the integral inner membrane proteins Tim23 and Tim17 in cooperation with Tim44 ...
and mitochondrial Hsp70. We describe here the discovery of a new pathway for the transport of members of the mitochondrial carrier family and other inner membrane proteins that contain internal targeting signals. Two related proteins in the intermembrane space, Tim10/Mrs11 and Tim12/Mrs5, interact sequentially with these precursors and facilitate their translocation across the outer membrane, irrespective of the membrane potential. Tim10 and Tim12 are found in a complex with Tim22, which takes over the precursor and mediates its membrane-potential-dependent insertion into the inner membrane. This interaction of Tim10 and Tim12 with the precursors depends on the presence of divalent metal ions. Both proteins contain a zinc-finger-like motif with four cysteines and bind equimolar amounts of zinc ions.
Mesh Terms:
Amino Acid Sequence, Biological Transport, Carrier Proteins, Cations, Divalent, Cloning, Molecular, Cross-Linking Reagents, Fungal Proteins, Intracellular Membranes, Membrane Proteins, Membrane Transport Proteins, Metals, Mitochondria, Mitochondrial ADP, ATP Translocases, Mitochondrial Membrane Transport Proteins, Molecular Sequence Data, Protein Precursors, Recombinant Fusion Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Nature
Date: Feb. 26, 1998
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