Abstract
The human homolog of the S. cerevisiaelN. crassa mitochondrial protein import receptor, Mas20p/MOM19, has been identified and characterized. Sequence similarities between these three proteins is most pronounced within the NH2-terminal third of the molecules. However, the mammalian protein exhibits only weak homology to the tetratricopeptide repeat B domain that is found in Mas20p/MOM19. huMas20p is targeted and inserted into the outer membrane of isolated rat heart mitochondria, in the Nin-Ccyto orientation. Antibodies directed against the soluble portion of huMas20p inhibited in vitro mitochondrial import of a diverse set of precursor proteins (including inner membrane uncoupling protein), but failed to block import of a fusion protein bearing the signal-anchor sequence of Mas20p itself. Finally, expression of huMAS20 complemented the respiratory defect of delta mas20 yeast cells. Together, these results demonstrate that huMAS20p is a component of the mammalian import apparatus.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Antibodies
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Base Sequence
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Cloning, Molecular
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DNA Primers
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Escherichia coli
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Genetic Complementation Test
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Humans
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Membrane Proteins / biosynthesis
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Membrane Proteins / metabolism*
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Membrane Transport Proteins*
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Mitochondria, Heart / metabolism*
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Mitochondrial Membrane Transport Proteins
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Mitochondrial Precursor Protein Import Complex Proteins
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Molecular Sequence Data
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Polymerase Chain Reaction
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Protein Precursors / analysis
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Protein Precursors / biosynthesis
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Rats
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Receptors, Cell Surface*
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Receptors, Cytoplasmic and Nuclear*
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
Substances
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Antibodies
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DNA Primers
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Membrane Proteins
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Membrane Transport Proteins
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Mitochondrial Membrane Transport Proteins
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Mitochondrial Precursor Protein Import Complex Proteins
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Protein Precursors
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Receptors, Cell Surface
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Receptors, Cytoplasmic and Nuclear
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Saccharomyces cerevisiae Proteins
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TOM20 protein, S cerevisiae
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TOMM20 protein, human
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Tomm20 protein, rat