InterPro domain: IPR002113

A variety of substrate carrier proteins that are involved in energy transfer are found in the inner mitochondrial membrane [ 1 , 2 , 3 , 4 , 5 ]. Such proteins include: ADP,ATP carrier protein (ADP/ATP translocase); 2-oxoglutarate/malate carrier protein; phosphate carrier protein; tricarboxylate transport protein (or citrate transport protein); Graves disease carrier protein; yeast mitochondrial proteins MRS3 and MRS4; yeast mitochondrial FAD carrier protein; and many others.

Sequence analysis of selected members of the carrier protein family has suggested the presence of six transmembrane (TM) domains, with varying degrees of sequence conservation and hydrophilicity [ 6 ]. The TM regions, and adjacent hydrophilic loops, are more highly conserved than other regions of the proteins [ 6 ]. All members of the family appear to consist of a tripartite structure, each of the repeated segments being ~100 residues in length [ 6 ]. Each repeat contains two TM domains, the first being morehydrophobic, with conserved glycyl and prolyl residues. Five of the six TM domains are followed by the conserved sequence (D/E)-Hy(K/R), where - denotes any residue and Hy is a hydrophobic position [ 6 ].

Mitochondrial ADP/ATP translocase, an abundant component of the inner membrane, carries ATP from the matrix into the inter-membrane space and transports ADP back [ 6 , 6 ]. The protein is an integral membrane protein that functions as a homodimer.

Mutations of the human ADP/ATP translocase 1 (also known as SLC25A4) gene cause mitochondrial diseases, such as PEOA2 and MTDPS12B [ 7 ].

This family contains proteins found in eucaryotes.

1. Mechanism and evolution of the uncoupling protein of brown adipose tissue. Trends Biochem. Sci. 15, 108-12
2. The mitochondrial carrier family of transport proteins: structural, functional, and evolutionary relationships. Crit. Rev. Biochem. Mol. Biol. 28, 209-33
3. Expansion of the mitochondrial carrier family. Res. Microbiol. 144, 671-2
4. Site-directed mutagenesis of the yeast mitochondrial ADP/ATP translocator. Six arginines and one lysine are essential. J. Mol. Biol. 230, 1159-70
5. The Molecular Mechanism of Transport by the Mitochondrial ADP/ATP Carrier. Cell 176, 435-447.e15
6. DNA sequences of two expressed nuclear genes for human mitochondrial ADP/ATP translocase. J. Mol. Biol. 206, 261-80
7. Recurrent De Novo Dominant Mutations in SLC25A4 Cause Severe Early-Onset Mitochondrial Disease and Loss of Mitochondrial DNA Copy Number. Am. J. Hum. Genet. 99, 860-876