Mitochondrial uncoupling protein 4 is a protein that in humans is encoded by the SLC25A27gene.
Mitochondrial uncoupling proteins (UCP) are members of the larger family of mitochondrial anion carrier proteins (MACP). UCPs separate oxidative phosphorylation from ATP synthesis with energy dissipated as heat, also referred to as the mitochondrial proton leak. UCPs facilitate the transfer of anions from the inner to the outer mitochondrial membrane and the return transfer of protons from the outer to the inner mitochondrial membrane. They also reduce the mitochondrial membrane potential in mammalian cells. Tissue specificity occurs for the different UCPs and the exact methods of how UCPs transfer H+/OH- are not known. UCPs contain the three homologous protein domains of MACPs. Transcripts of this gene are detected only in brain tissue and are specifically modulated by various environmental conditions. Recently, the proton transport activity of UCP4 has also been shown to be activated by fatty acids and inhibited by purine nucleotides.  In addition, reconstituted UCP4 exhibited a distinct conformation, compared to other UCPs in the family.
^Mao W, Yu XX, Zhong A, Li W, Brush J, Sherwood SW, Adams SH, Pan G (Mar 1999). "UCP4, a novel brain-specific mitochondrial protein that reduces membrane potential in mammalian cells". FEBS Lett443 (3): 326–30. doi:10.1016/S0014-5793(98)01713-X. PMID10025957.
Muzzin P (2002). "The uncoupling proteins.". Ann. Endocrinol. (Paris)63 (2 Pt 1): 106–10. PMID11994670.
Bonaldo MF, Lennon G, Soares MB (1997). "Normalization and subtraction: two approaches to facilitate gene discovery.". Genome Res.6 (9): 791–806. doi:10.1101/gr.6.9.791. PMID8889548.
Yu XX, Mao W, Zhong A et al. (2000). "Characterization of novel UCP5/BMCP1 isoforms and differential regulation of UCP4 and UCP5 expression through dietary or temperature manipulation.". FASEB J.14 (11): 1611–8. doi:10.1096/fj.14.11.1611. PMID10928996.CS1 maint: Explicit use of et al. (link)
Ota T, Suzuki Y, Nishikawa T et al. (2004). "Complete sequencing and characterization of 21,243 full-length human cDNAs.". Nat. Genet.36 (1): 40–5. doi:10.1038/ng1285. PMID14702039.CS1 maint: Explicit use of et al. (link)
Liu D, Chan SL, de Souza-Pinto NC et al. (2007). "Mitochondrial UCP4 mediates an adaptive shift in energy metabolism and increases the resistance of neurons to metabolic and oxidative stress.". Neuromolecular Med.8 (3): 389–414. doi:10.1385/NMM:8:3:389. PMID16775390.CS1 maint: Explicit use of et al. (link)
Chan SL, Liu D, Kyriazis GA et al. (2007). "Mitochondrial uncoupling protein-4 regulates calcium homeostasis and sensitivity to store depletion-induced apoptosis in neural cells.". J. Biol. Chem.281 (49): 37391–403. doi:10.1074/jbc.M605552200. PMID17035241.CS1 maint: Explicit use of et al. (link)
Yasuno K, Ando S, Misumi S et al. (2007). "Synergistic association of mitochondrial uncoupling protein (UCP) genes with schizophrenia.". Am. J. Med. Genet. B Neuropsychiatr. Genet.144 (2): 250–3. doi:10.1002/ajmg.b.30443. PMID17066476.CS1 maint: Explicit use of et al. (link)