The yeast mitochondrial ADP/ATP carrier functions as a monomer in mitochondrial membranes

Lisa Bamber, Marilyn Harding, Magnus Monné, Dirk-Jan Slotboom, Edmund R.S. Kunji, L Barber


75 Citaten (Scopus)
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Mitochondrial carriers are believed widely to be dimers both in structure and function. However, the structural fold is a barrel of six transmembrane α-helices without an obvious dimerisation interface. Here, we show by negative dominance studies that the yeast mitochondrial ADP/ATP carrier 2 from Saccharomyces cerevisiae (AAC2) is functional as a monomer in the mitochondrial membrane. Adenine nucleotide transport by wild-type AAC2 is inhibited by the sulfhydryl reagent 2-sulfonatoethyl-methanethiosulfonate (MTSES), whereas the activity of a mutant AAC2, devoid of cysteines, is unaffected. Wild-type and cysteine-less AAC2 were coexpressed in different molar ratios in yeast mitochondrial membranes. After addition of MTSES the residual transport activity correlated linearly with the fraction of cysteine-less carrier present in the membranes, and so the two versions functioned independently of each other. Also, the cysteine-less and wild-type carriers were purified separately, mixed in defined ratios and reconstituted into liposomes. Again, the residual transport activity in the presence of MTSES depended linearly on the amount of cysteine-less carrier. Thus, the entire transport cycle for ADP/ATP exchange is carried out by the monomer.
Originele taal-2English
Pagina's (van-tot)10830 - 10834
Aantal pagina's5
TijdschriftProceedings of the National Academy of Science of the United States of America
Nummer van het tijdschrift26
StatusPublished - 26-jun-2007

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