MPI1, an essential gene encoding a mitochondrial membrane protein, is possibly involved in protein import into yeast mitochondria.

Maarse, Ammy C.; Blom, Joke; Grivell, Leslie A.; Meijer, Michiel

doi:10.1002/j.1460-2075.1992.tb05446.x

Cited by 166 publications

(149 citation statements)

References 60 publications

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“…MPI1 has been identified as the first protein of the inner membrane involved in precursor import [20][21][22]. MPI1 or ISP45 was later renamed MIM44 to make clear that it is an inner membrane protein.…”

Section: The Import Machinery Of the Inner Membranementioning

confidence: 99%

Mitochondrial protein import: Mechanisms, components and energetics

Schwarz

Neupert

1994

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The transport of nuclear-encoded proteins from the cytosol into mitochondria is mediated by targeting (signal) sequences present on precursor forms. Most precursors of the mitochondrial matrix possess amino-terminal signals which characteristically contain hydroxylated and basic amino acids and lack acidic residues. With a minority of precursor proteins, internal sequence motifs can direct proteins to the mitochondria (Planner, N., Hoeben, P., Tropschug, M. and Neupert, W. (1987) J. Biol. Chem. 262, 14851-14854). The presence of a mitochondrial targeting sequence alone, however, is not sufficient for specific targeting to the organeUe and further to the various subcompartments. There is the need for components which recognise the targeting sequences and others which keep the precursor protein in a translocation-competent form. Beyond the recognition step, components are required which mediate transiocation across the mitochondrial membranes. Mitochondria possess two translocation machineries, one in the outer membrane and one in the inner membrane. The matrix space harbors a number of factors which participate in the import of proteins, in their unfolding and folding. Energy is required at several steps of these processes.

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Section: The Import Machinery Of the Inner Membranementioning

confidence: 99%

Mitochondrial protein import: Mechanisms, components and energetics

Schwarz

Neupert

1994

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…Import of presequence targeted proteins into the mitochondrial matrix generally requires a membrane potential (⌬ ) across the mitochondrial inner membrane and the TIM17-23 translocase machinery (10 -14). The TIM17-23 translocase, along with the membrane-bound TIM44 and the matrix chaperone mt-Hsp70 (15)(16)(17)(18)(19)(20)(21), mediate the translocation across the inner membrane into the matrix. Alternatively, import of several inner membrane proteins, such as the ADP/ATP carrier and components of the TIM machinery itself, is mediated by the TIM22-54 translocase (22)(23)(24).…”

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confidence: 99%

The DNA Helicase, Hmi1p, Is Transported into Mitochondria by a C-terminal Cleavable Targeting Signal

Lee

Sedman

Neupert

et al. 1999

Journal of Biological Chemistry

104

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We have identified a novel mitochondrial targeting signal in the precursor of the DNA helicase Hmi1p of Saccharomyces cerevisiae that is located at the C terminus of the protein. Similar to classical N-terminal presequences, this C-terminal targeting signal consists of a stretch of positively charged amino acids that has the potential to form an amphipathic ␣-helix. Deletion of the C-terminal 36 amino acids of helicase resulted in loss of import into mitochondria, while deletion of the N-terminal 40 amino acids had no effect. When C-terminal regions of the helicase were placed at the C terminus of a passenger protein, dihydrofolate reductase, the resulting fusion proteins were directed into the mitochondrial matrix, and the C-terminal region of helicase became proteolytically processed. Import of helicase occurs in a C-to N-terminal direction; it requires a membrane potential and the TIM17-23 translocase together with mitochondrial Hsp70. Helicase is the only mitochondrial matrix protein identified thus far with a cleavable targeting signal at its C terminus.

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“…Because this protein had been caught by two different approaches, it is very probably Further characterization of the inhibitory rabbit antiserum led us to yet another putative component of the protein import system in the inner membrane, a 40-kDa integral inner membrane protein (M. Horst, unpubl.). The same protein was recently found by an elegant genetic approach that selected for yeast mutants whose protein import across the inner membrane was defective (Maarse et al, 1992). In this approach, a cytosolic enzyme of pyrimidine biosynthesis was fused to a matrix-targeting signal and thereby mistargeted to the mitochondrial matrix where it was nonfunctional.…”

Section: The Protein Import System Of the Inner Membranementioning

confidence: 85%

The protein import machinery of mitochondria

Schatz

1993

Protein Science

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MPI1, an essential gene encoding a mitochondrial membrane protein, is possibly involved in protein import into yeast mitochondria.

Cited by 166 publications

References 60 publications

Mitochondrial protein import: Mechanisms, components and energetics

Mitochondrial protein import: Mechanisms, components and energetics

The DNA Helicase, Hmi1p, Is Transported into Mitochondria by a C-terminal Cleavable Targeting Signal

The protein import machinery of mitochondria

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