Role of the ABC Transporter Mdl1 in Peptide Export from Mitochondria

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Science  16 Mar 2001:
Vol. 291, Issue 5511, pp. 2135-2138
DOI: 10.1126/science.1056957

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ATP-binding cassette (ABC) adenosine triphosphatases actively transport a wide variety of compounds across biological membranes. Here, the ABC protein Mdl1 was identified as an intracellular peptide transporter localized in the inner membrane of yeast mitochondria. Mdl1 was required for mitochondrial export of peptides with molecular masses of ∼2100 to 600 daltons generated by proteolysis of inner-membrane proteins by the m-AAA protease in the mitochondrial matrix. Proteolysis by the i-AAA protease in the intermembrane space led to the release of similar-sized peptides independent of Mdl1. Thus, two pathways of peptide efflux from mitochondria exist that may allow communication between mitochondria and their cellular environment.

  • * These authors contributed equally to this work.

  • To whom correspondence should be addressed. E-mail: lesley.young{at}; thomas.langer{at}

  • Present address: Institut für Genetik, Universität zu Köln, Zülpicher Strasse 47, 50647 Köln, Germany.

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