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- ****************************************************
- * Mitochondrial energy transfer proteins signature *
- ****************************************************
-
- Different types of substrate carrier proteins involved in energy transfer are
- found in the inner mitochondrial membrane [1,2,3,4]. 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
- species.
- - 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
- oxoglutarate/isocitrate shuttles.
- - 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
- matrix.
- - The Grave's disease carrier protein (GDC), a protein of unknown function
- 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
- mitochondrion.
- - Yeast protein ACR1 [5], which seems essential for acetyl-CoA synthetase
- activity.
- - Yeast protein PMT1 [6].
- - Yeast protein YMC1 [7].
-
- 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 [8]. This protein, found in the
- endosperm of kernels, could play a role in amyloplast membrane transport.
- - Candida boidinii peroxisomal membrane protein PMP47 [9]. PMP47 is an
- integral membrane protein of the peroxisome and it may play a role as a
- transporter.
-
- 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. As a signature
- pattern, we selected one of the most conserved regions in the repeated domain,
- located just after the first transmembrane region.
-
- -Consensus pattern: P-x-[DE]-x-[LIVAT]-[RK]-x-[LRH]-[LIVMFY]
- -Sequences known to belong to this class detected by the pattern: ALL, except
- for PMP47.
- -Other sequence(s) detected in SWISS-PROT: 185. However, in all these
- proteins, the pattern is found only ONCE while it is found two to three times
- in members of this family.
- -Last update: June 1994 / Text revised.
-
- [ 1] Klingenberg M.
- Trends Biochem. Sci. 15:108-112(1990).
- [ 2] Walker J.E.
- Curr. Opin. Struct. Biol. 2:519-526(1992).
- [ 3] Nelson D.R., Lawson J.E., Klingenberg M., Douglas M.G.
- J. Mol. Biol. 230:1159-1170(1993).
- [ 4] Fernandez M., Fernandez E., Rodicio R.
- Mol. Gen. Genet. 242:727-735(1994).
- [ 5] Palmieri F.
- FEBS Lett. 346:48-54(1994).
- [ 6] Colleaux L., Richard G.-F., Thierry A., Dujon B.
- Yeast 8:325-336(1992).
- [ 7] Graf R., Baum B., Braus G.H.
- Yeast 9:301-305(1993).
- [ 8] Sullivan T.D., Strelow L.I., Illingworth C.A., Phillips R.L.,
- Nelson O.E. Jr.
- Plant Cell 3:1337-1348(1991).
- [ 9] Jank B., Habermann B., Schweyen R.J., Link T.A.
- Trends Biochem. Sci. 18:427-428(1993).
-