Different types of substrate carrier proteins involved in energy transfer are
found in the inner mitochondrial membrane [1,2,3,4,5]. These are:
The ADP,ATP carrier protein (AAC) (ADP/ATP translocase) which exports ATP
into the cytosol and imports ADP into the mitochondrial matrix. The
sequence of AAC has been obtained from various mammalian, plant and fungal
The 2-oxoglutarate/malate carrier protein (OGCP), which exports
2-oxoglutarate into the cytosol and imports malate or other dicarboxylic
acids into the mitochondrial matrix. This protein plays an important role
in several metabolic processes such as the malate/aspartate and the
The phosphate carrier protein, which transports phosphate groups from the
cytosol into the mitochondrial matrix.
The brown fat uncoupling protein (UCP) which dissipates oxidative energy
into heat by transporting protons from the cytosol into the mitochondrial
The tricarboxylate transport protein (or citrate transport protein) which
is involved in citrate-H+/malate exchange. It is important for the
bioenergetics of hepatic cells as it provides a carbon source for fatty
acid and sterol biosyntheses, and NAD for the glycolytic pathway.
The Grave's disease carrier protein (GDC), a protein of unknown function
recognized by IgG in patients with active Grave's disease.
Yeast mitochondrial proteins MRS3 and MRS4. The exact function of these
proteins is not known. They suppress a mitochondrial splice defect in the
first intron of the COB gene and may act as carriers, exerting their
suppressor activity by modulating solute concentrations in the
Yeast mitochondrial FAD carrier protein (gene FLX1).
Yeast protein ACR1 , which seems essential for acetyl-CoA synthase
Yeast protein PET8.
Yeast protein PMT.
Yeast protein RIM2.
Yeast protein YHM1/SHM1.
Yeast protein YMC1.
Yeast protein YMC2.
Yeast hypothetical proteins YBR291c, YEL006w, YER053c, YFR045w, YHR002w,
Caenorhabditis elegans hypothetical protein K11H3.3.
Two other proteins have been found to belong to this family, yet are not
localized in the mitochondrial inner membrane:
Maize amyloplast Brittle-1 protein. This protein, found in the endosperm of
kernels, could play a role in amyloplast membrane transport.
Candida boidinii peroxisomal membrane protein PMP47 . PMP47 is an
integral membrane protein of the peroxisome and it may play a role as a
These proteins all seem to be evolutionary related. Structurally, they consist
of three tandem repeats of a domain of approximately one hundred residues.
Each of these domains contains two transmembrane regions.
The profile we developed covers the entire solute carrier (Solcar) repeat.
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