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Updated: Jun 20, 2026

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria
Published on: January 7, 2022
Roles of Tom70 in import of presequence-containing mitochondrial proteins
Hayashi Yamamoto1, Kenji Fukui, Hisashi Takahashi
1Department of Chemistry, Graduate School of Science, Japan Science and Technology Agency, Research Centre for Material Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
Abstract:
Mitochondrial protein traffic requires precise recognition of the mitochondrial targeting signals by the import receptors on the mitochondrial surface including a general import receptor Tom20 and a receptor for presequence-less proteins, Tom70. Here we took a proteome-wide approach of mitochondrial protein import in vitro to find a set of presequence-containing precursor proteins for recognition by Tom70. The presequences of the Tom70-dependent precursor proteins were recognized by Tom20, whereas their mature parts exhibited Tom70-dependent import when attached to the presequence of Tom70-independent precursor proteins. The mature parts of the Tom70-dependent precursor proteins have the propensity to aggregate, and the presence of the receptor domain of Tom70 prevents their aggregate formation. Therefore Tom70 plays the role of a docking site for not only cytosolic chaperones but also aggregate-prone substrates to maintain their solubility for efficient transfer to downstream components of the mitochondrial import machineries.
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