The N‐terminal half of a mitochondrial presequence peptide inserts into cardiolipin‐containing membranes Consequences for the action of a transmembrane potential

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Abstract
The orientation of a mitochondrial presequence peptide, associated with anionic lipid‐containing model membranes, was investigated. The peptide inserts with its N‐terminal α‐helical part into cardiolipin (CL) monolayers so that the N‐terminal 14 residues are protected from proteinase K. In phosphatidylglycerol (PG) monolayers the inserted peptide was fully accessible to the protease. A consequence of the different orientations of the peptide was that membrane potential‐dependent protection from trypsin was much faster for the peptide bound to PG‐containing vesicles compared to CL‐containing membranes, suggesting that in the mitochondrial protein import process other components of the import apparatus are involved in the efficient potential‐driven translocation of presequences across the inner mitochondrial membrane.