Identification of the human mitochondrial protein import receptor, huMas20p. Complementation of delta mas20 in yeast.
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.
Goping
I S
IS
Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
Millar
D G
DG
Shore
G C
GC
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli; D005816:Genetic Complementation Test; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008929:Mitochondria, Heart / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D000906:Antibodies; D017931:DNA Primers; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011498:Protein Precursors; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; C489350:TOM20 protein, S cerevisiae; C084008:TOMM20 protein, human; C489998:Tomm20 protein, rat