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Isolation of mRNAs Associated with Yeast Mitochondria to Study Mechanisms of Localized Translation
Published on: March 14, 2014
MPI1, an essential gene encoding a mitochondrial membrane protein, is possibly involved in protein import into yeast
A C Maarse1, J Blom, L A Grivell
1Department of Molecular Cell Biology, University of Amsterdam, The Netherlands.
Abstract:
To identify components of the mitochondrial protein import pathway in yeast, we have adopted a positive selection procedure for isolating mutants disturbed in protein import. We have cloned and sequenced a gene, termed MPI1, that can rescue the genetic defect of one group of these mutants. MPI1 encodes a hydrophilic 48.8 kDa protein that is essential for cell viability. Mpi1p is a low abundance and constitutively expressed mitochondrial protein. Mpi1p is synthesized with a characteristic mitochondrial targeting sequence at its amino-terminus, which is most probably proteolytically removed during import. It is a membrane protein, oriented with its carboxy-terminus facing the intermembrane space. In cells depleted of Mpi1p activity, import of the precursor proteins that we tested thus far, is arrested. We speculate that the Mpi1 protein is a component of a proteinaceous import channel for translocation of precursor proteins across the mitochondrial inner membrane.
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