Publications

• Identification of the mitochondrial ATP-Mg/Pi transporter. Bacterial expression, reconstitution, functional characterization, and tissue distribution.

  Fiermonte G., De Leonardis F., Todisco S., Palmieri L., Lasorsa F.M., Palmieri F.

  The mitochondrial carriers are a family of transport proteins that, with a few exceptions, are found in the inner membranes of mitochondria. They shuttle metabolites, nucleotides, and cofactors through this membrane and thereby connect and/or regulate cytoplasm and matrix functions. ATP-Mg is tran ... >> More

  The mitochondrial carriers are a family of transport proteins that, with a few exceptions, are found in the inner membranes of mitochondria. They shuttle metabolites, nucleotides, and cofactors through this membrane and thereby connect and/or regulate cytoplasm and matrix functions. ATP-Mg is transported in exchange for phosphate, but no protein has ever been associated with this activity. We have isolated three human cDNAs that encode proteins of 458, 468, and 489 amino acids with 66-75% similarity and with the characteristic features of the mitochondrial carrier family in their C-terminal domains and three EF-hand Ca(2+)-binding motifs in their N-terminal domains. These proteins have been overexpressed in Escherichia coli and reconstituted into phospholipid vesicles. Their transport properties and their targeting to mitochondria demonstrate that they are isoforms of the ATP-Mg/Pi carrier described in the past in whole mitochondria. The tissue specificity of the three isoforms shows that at least one isoform was present in all of the tissues investigated. Because phosphate recycles via the phosphate carrier in mitochondria, the three isoforms of the ATP-Mg/Pi carrier are most likely responsible for the net uptake or efflux of adenine nucleotides into or from the mitochondria and hence for the variation in the matrix adenine nucleotide content, which has been found to change in many physiopathological situations. << Less

  J. Biol. Chem. 279:30722-30730(2004) [PubMed] [EuropePMC]

  This publication is cited by 11 other entries.

• Characterization of SCaMC-3-like/slc25a41, a novel calcium-independent mitochondrial ATP-Mg/Pi carrier.

  Traba J., Satrustegui J., del Arco A.

  The SCaMCs (small calcium-binding mitochondrial carriers) constitute a subfamily of mitochondrial carriers responsible for the ATP-Mg/P(i) exchange with at least three paralogues in vertebrates. SCaMC members are proteins with two functional domains, the C-terminal transporter domain and the N-ter ... >> More

  The SCaMCs (small calcium-binding mitochondrial carriers) constitute a subfamily of mitochondrial carriers responsible for the ATP-Mg/P(i) exchange with at least three paralogues in vertebrates. SCaMC members are proteins with two functional domains, the C-terminal transporter domain and the N-terminal domain which harbours calcium-binding EF-hands and faces the intermembrane space. In the present study, we have characterized a shortened fourth paralogue, SCaMC-3L (SCaMC-3-like; also named slc25a41), which lacks the calcium-binding N-terminal extension. SCaMC-3L orthologues are found exclusively in mammals, showing approx. 60% identity to the C-terminal half of SCaMC-3, its closest paralogue. In mammalian genomes, SCaMC-3 and SCaMC-3L genes are adjacent on the same chromosome, forming a head-to-tail tandem array, and show identical exon-intron boundaries, indicating that SCaMC-3L could have arisen from an SCaMC-3 ancestor by a partial duplication event which occurred prior to mammalian radiation. Expression and functional data suggest that, following the duplication event, SCaMC-3L has acquired more restrictive functions. Unlike the broadly expressed longer SCaMCs, mouse SCaMC-3L shows a limited expression pattern; it is preferentially expressed in testis and, at lower levels, in brain. SCaMC-3L transport activity was studied in yeast deficient in Sal1p, the calcium-dependent mitochondrial ATP-Mg/P(i) carrier, co-expressing SCaMC-3L and mitochondrial-targeted luciferase, and it was found to perform ATP-Mg/P(i) exchange, in a similar manner to Sal1p or other ATP-Mg/P(i) carriers. However, metabolite transport through SCaMC-3L is calcium-independent, representing a novel mechanism involved in adenine nucleotide transport across the inner mitochondrial membrane, different to ADP/ATP translocases or long SCaMC paralogues. << Less

  Biochem. J. 418:125-133(2009) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• The ATP-Mg/Pi carrier of rat liver mitochondria catalyzes a divalent electroneutral exchange.

  Joyal J.L., Aprille J.R.

  Net transport of ATP-Mg or ADP in exchange for phosphate in isolated rat liver mitochondria has been shown to be an electroneutral process mediated by the ATP-Mg/Pi carrier. We compared the steady state distribution ratios of phosphate, ATP-Mg, and ADP at a pH of 7.4 to determine whether the dival ... >> More

  Net transport of ATP-Mg or ADP in exchange for phosphate in isolated rat liver mitochondria has been shown to be an electroneutral process mediated by the ATP-Mg/Pi carrier. We compared the steady state distribution ratios of phosphate, ATP-Mg, and ADP at a pH of 7.4 to determine whether the divalent or monovalent form of these anions is the transported substrate. The log of the divalent ATP-Mg distribution ratio (in/out) approached the log of the divalent phosphate distribution ratio (approximately 0.85), which was approximately twice the value of the delta pH (approximately 0.40) across the inner mitochondrial membrane. This steady state relationship held under several different conditions, e.g. when the medium ATP concentration was varied or if the phosphate gradient was modified by partial uncoupling with the proton ionophore, carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Unidirectional ADP efflux in exchange for external ADP or ATP-Mg was stimulated by an increase in matrix H+. The log of the trivalent ADP distribution ratio (approximately 1.20) approached 3 times the value of delta pH. All these data are consistent with the model of an electroneutral exchange of divalent phosphate (HPO2-4) for divalent ATP-Mg (ATP-Mg2-) or for divalent protonated ADP (HADP2-). We conclude that this transport mechanism accounts for the adenine nucleotide concentration gradient that normally exists between the matrix and external medium. << Less

  J Biol Chem 267:19198-19203(1992) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.