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Updated: Jun 4, 2026

Reconstitution of Msp1 Extraction Activity with Fully Purified Components
Published on: August 10, 2021
TIM23-mediated insertion of transmembrane α-helices into the mitochondrial inner membrane
Salomé Calado Botelho1, Marie Osterberg, Andreas S Reichert
1Department of Biochemistry and Biophysics, Center for Biomembrane Research, Stockholm University, Stockholm, Sweden.
Abstract:
While overall hydrophobicity is generally recognized as the main characteristic of transmembrane (TM) α-helices, the only membrane system for which there are detailed quantitative data on how different amino acids contribute to the overall efficiency of membrane insertion is the endoplasmic reticulum (ER) of eukaryotic cells. Here, we provide comparable data for TIM23-mediated membrane protein insertion into the inner mitochondrial membrane of yeast cells. We find that hydrophobicity and the location of polar and aromatic residues are strong determinants of membrane insertion. These results parallel what has been found previously for the ER. However, we see striking differences between the effects elicited by charged residues flanking the TM segments when comparing the mitochondrial inner membrane and the ER, pointing to an unanticipated difference between the two insertion systems.
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