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Updated: Sep 26, 2026

Measurement of Protein Import Capacity of Skeletal Muscle Mitochondria
Published on: January 7, 2022
Comparison of the TIM and TOM channel activities of the mitochondrial protein import complexes
Concepción Muro1, Serguei M Grigoriev, Dawn Pietkiewicz
1Departamento de Bioquímica y Biología Molecular y Genética, Facultad de Veterinaria, Universidad de Extremadura, 10071 Cáceres, Spain.
Abstract:
Water-filled channels are central to the process of translocating proteins since they provide aqueous pathways through the hydrophobic environment of membranes. The Tom and Tim complexes translocate precursors across the mitochondrial outer and inner membranes, respectively, and contain channels referred to as TOM and TIM (previously called PSC and MCC). In this study, little differences were revealed from a direct comparison of the single channel properties of the TOM and TIM channels of yeast mitochondria. As they perform similar functions in translocating proteins across membranes, it is not surprising that both channels are high conductance, voltage-dependent channels that are slightly cation selective. Reconstituted TIM and TOM channel activities are not modified by deletion of the outer membrane channel VDAC, but are similarly affected by signal sequence peptides.
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