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Updated: Jun 18, 2026

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria
Published on: January 7, 2022
Transport of proteins across or into the mitochondrial outer membrane
1Department of Chemistry, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan. endo@biochem.chem.nagoya-u.ac.jp
Abstract:
Mitochondria are surrounded by two biological membranes. The outer mitochondrial membrane contains two major translocators, the TOM40 (TOM) and TOB/SAM complexes for protein translocation across and/or insertion into the outer membrane. The TOM40 complex functions as an entry gate for most mitochondrial proteins, and the TOB/SAM complex as a specialized insertion machinery for beta-barrel membrane proteins. In order to handle loosely folded or unfolded precursor polypeptides, those translocators cooperate with chaperones in the cytosol and intermembrane space, and also exhibit chaperone-like functions on their own. Several alpha-helical membrane proteins take 'non-standard' routes to be inserted into the outer membrane. Here we review the current view on a remarkable variety of mechanisms of protein transport taking place at the mitochondrial outer membrane.
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