Abstract
The SLC6 family is a diverse set of transporters that mediate solute translocation across cell plasma membranes by coupling solute transport to the cotransport of sodium and chloride down their electrochemical gradients. These transporters probably have 12 transmembrane domains, with cytoplasmic N- and C-terminal tails, and at least some may function as homo-oligomers. Family members include the transporters for the inhibitory neurotransmitters GABA and glycine, the aminergic transmitters norepinephrine, serotonin, and dopamine, the osmolytes betaine and taurine, the amino acid proline, and the metabolic compound creatine. In addition, this family includes a system B0+ cationic and neutral amino acid transporter, and two transporters for which the solutes are unknown. In general, SLC6 transporters act to regulate the level of extracellular solute concentrations. In the central and the peripheral nervous system, these transporters can regulate signaling among neurons, are the sites of action of various drugs of abuse, and naturally occurring mutations in several of these proteins are associated with a variety of neurological disorders. For example, transgenic animals lacking specific aminergic transporters show profoundly disturbed behavioral phenotypes and probably represent excellent systems for investigating psychiatric disease. SLC6 transporters are also found in many non-neural tissues, including kidney, intestine, and testis, consistent with their diverse physiological roles. Transporters in this family represent attractive therapeutic targets because they are subject to multiple forms of regulation by many different signaling cascades, and because a number of pharmacological agents have been identified that act specifically on these proteins.
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References
Adkins EM, Barker EL, Blakely RD (2001) Interactions of tryptamine derivatives with serotonin transporter species variants implicate transmembrane domain 1 in substrate recognition. Mol Pharmacol 59:514–523
Androutsellis-Theotokis A, Goldberg NR, Ueda K, Beppu T, Beckman ML, Das S, Javitch JA Rudnick G (2003) Characterization of a functional bacterial homologue of sodium-dependent neurotransmitter transporters. J Biol Chem 278:12703–12709
Atkinson BN, Bell SC, De Vivo M, Kowalski LR, Lechner SM, Ognyanov VI, Tham CS, Tsai C, Jia J, Ashton D, Klitenick MA (2001) ALX 5407: a potent, selective inhibitor of the hGlyT1 glycine transporter. Mol Pharmacol 60:1414–1420
Aubrey KR, Mitrovic AD, Vandenberg RJ (2000) Molecular basis for proton regulation of glycine transport by glycine transporter subtype 1b. Mol Pharmacol 58:129–35
Bauman AL, Apparsundaram S, Ramamoorthy S, Wadzinski BE, Vaughan RA, Blakely RD (2000) Cocaine and antidepressant-sensitive biogenic amine transporters exist in regulated complexes with protein phosphatase 2A. J Neurosci 20:7571–7578
Bauman PA, Blakely RD (2002) Determinants within the C-terminus of the human norepinephrine transporter dictate transporter trafficking, stability, and activity. Arch Biochem Biophys 404:80–91
Beckman ML, Quick MW (1998) Neurotransmitter transporters: regulators of function and functional regulation. J Membr Biol 164:1–10
Bennett ER, Su H, Kanner BI (2000) Mutation of arginine 44 of GAT-1, a (Na+ + Cl−-coupled gamma-aminobutyric acid transporter from rat brain, impairs net flux but not exchange. J Biol Chem 275:34106–34113
Blakely RD, Bauman AL (2000) Biogenic amine transporters: regulation in flux. Curr Opin Neurobiol 10:328–336
Borden LA, Smith KE, Hartig PR, Branchek TA, Weinshank RL (1992) Molecular heterogeneity of the gamma-aminobutyric acid (GABA) transporter system. Cloning of two novel high affinity GABA transporters from rat brain. J Biol Chem 267:21098–21104
Bossi E, Giovannardi S, Binda F, Forlani G, Peres A (2002) Role of anion-cation interactions on the pre-steady-state currents of the rat Na+-Cl−-dependent GABA cotransporter rGAT1. J Physiol (Lond) 541:343–350
Carneiro AM, Ingram SL, Beaulieu J-M, Sweeney A, Amara SG, Thomas SM, Caron MG, Torres GE (2002) The multiple LIM domain-containing adaptor protein Hic-5 synaptically colocalizes and interacts with the dopamine transporter. J Neurosci 22:7045–7054
Chang AS, Starnes DM, Chang SM (1998) Possible existence of quaternary structure in the high-affinity serotonin transport complex. Biochem Biophys Res Commun 249:416–412
Chen J-G, Rudnick G (2000) Permeation and gating residues in serotonin transporter. Proc Natl Acad Sci USA 97:1044–1049
Chen N, Vaughan RA, Reith MEA (2001) The role of conserved tryptophan and acidic residues in the human dopamine transporter as characterized by site-directed mutagenesis. J Neurochem 77:1116–1127
Chiu C-S, Jensen K, Sokolova I, Wang D, Li M, Deshpande P, Davidson N, Mody I, Quick MW, Quake SR, Lester HA (2002) Counting GABA transporters at presynaptic terminals of knock-in mice carrying GAT1-GFP fusions. J Neurosci 22:10251–10266
Deken SL, Beckman M, Boos L, Quick MW (2000) Permeation through GABA transporters is regulated by syntaxin 1A. Nat Neurosci 3:998–1003
Deken SL, Wang D, Quick MW (2003) Plasma membrane GABA transporters undergo rapid recycling and reside on distinct synaptic-like vesicles. J Neurosci 23:1563–1568
Evans J, Herdon H, Cairns W, O'Brien E, Chapman C, Terrett J, Gloger I (1999) Cloning, functional characterisation and population analysis of a variant form of the human glycine type 2 transporter. FEBS Lett 463:301–306
Falkenburger BH, Barstow KL, Mintz IM (2001) Dendrodendritic inhibition through reversal of dopamine transport. Science 293:2465–2470
Farmer MK, Robbins MJ, Medhurst AD, Campbell DA, Ellington K, Duckworth M, Brown AM, Middlemiss DN, Price GW, Pangalos MN (2000) Cloning and characterization of human NTT5 and v7-3: two orphan transporters of the Na+/Cl−-dependent neurotransmitter transporter gene family. Genomics 70:241–252
Foster JD, Pananusorn B, Vaughan RA (2002) Dopamine transporters are phosphorylated on N-terminal serines in rat striatum. J Biol Chem 277:25178–25186
Gainetdinov RR, Sotnikova TD, Caron MG (2002) Monoamine transporter pharmacology and mutant mice. Trends Pharmacol Sci 23:367–373
Geerlings A, Lopez-Corcuera B, Aragon C (2000) Characterization of the interactions between the glycine transporters GLYT1 and GLYT2 and the SNARE protein syntaxin 1A. FEBS Lett 470:51–54
Giros B, el Mestikawy S, Godinot N, Zheng K, Han H, Yang-Feng T, Caron MG (1992) Cloning, pharmacological characterization, and chromosome assignment of the human dopamine transporter. Mol Pharmacol 42:383–390
Grånäs C, Ferrer J, Loland CJ, Javitch JA, Gether U (2003) N-terminal truncation of the dopamine transporter abolishes phorbol ester- and substance P receptor-stimulated phosphorylation without impairing transporter internalization. J Biol Chem 278:4990–5000
Gu HH, Wu X, Giros B, Caron MG, Caplan MJ, Rudnick G (2001) The NH2-terminus of norepinephrine transporter contains a basolateral localization signal for epithelial cells. Mol Biol Cell 12:3797–807
Guastella J, Nelson N, Nelson H, Czyzyk L, Keynan S, Miedel MC, Davidson N, Lester HA, Kanner BI (1990) Cloning and expression of a rat brain GABA transporter. Science 249:1303–1306
Hanley JG, Jones EM, Moss SJ (2000) GABA receptor rho1 subunit interacts with a novel splice variant of the glycine transporter, GLYT-1. J Biol Chem 275:840–846
Hastrup H, Karlin A, Javitich JA (2001) Symmetrical dimer of the human dopamine transporter revealed by cross-linking Cys-306 at the extracellular end of the sixth transmembrane segment. Proc Natl Acad Sci USA 98:10055–10060
Iyer GS, Krahe R, Goodwin LA, Doggett NA, Siciliano MJ, Funanage VL, Proujansky R (1996) Identification of a testis-expressed creatine transporter gene at 16p11.2 and confirmation of the X-linked locus to Xq28. Genomics 34:143–146
Jayanthi LD, Wilson JJ, Montalvo J, DeFelice LJ (2000) Differential regulation of mammalian brain-specific proline transporter by calcium and calcium-dependent protein kinases. Br J Pharmacol 129:465–470
Jess U, Far OEI, Kirsch J, Betz H (2002) Interaction of the C-terminal region of the rat serotonin transporter with MacMARCKS modulates 5-HT uptake regulation by protein kinase C. Biochem Biophys Res Commun 294:272–279
Kamdar G, Penado KMY, Rudnick G, Stephan MM (2001) Functional role of critical strip residues in transmembrane span 7 of the serotonin transporter. J Biol Chem 276:4038–4045
Kang YS, Ohtsuki S, Takanaga H, Tomi M, Hosoya K, Terasaki T (2002) Regulation of taurine transport at the blood-brain barrier by tumor necrosis factor-alpha, taurine, and hypertonicity. J Neurochem 83:1188–1195
Khoshbouei H, Wang H, Lechleiter JD, Javitch JA, Galli A (2003) Amphetamine-induced DA efflux: a voltage sensitive and intracellular Na+-dependent mechanism. J Biol Chem 278:12070–12077
Kilic F, Rudnick G (2000) Oligomerization of the serotonin transporter and its functional consequences. Proc Natl Acad Sci USA 97:3106–3111
Kitayama S, Shimada S, Xu H, Markham L, Donovan DM, Uhl GR (1992) Dopamine transporter site-directed mutations differentially alter substrate transport and cocaine binding. Proc Natl Acad Sci USA 89:7782–7785
Kwon HM (1996) Transcriptional regulation of the betaine/gamma-aminobutyric acid transporter by hypertonicity. Biochem Soc Trans 24:853–856
Lee FJS, Liu F, Pristupa ZB, Niznik HB (2001) Direct binding and functional coupling of α-synuclein to the dopamine transporters accelerate dopamine-induced apoptosis. FASEB J 15:916–926
Lesch KP, Mossner R (1998) Genetically driven variation in serotonin uptake: is there a link to affective spectrum, neurodevelopmental, and neurodegenerative disorders? Biol Psychiatry 44:179–192
Lin Z, Wang W, Uhl GR (2000) Dopamine transporter tryptophan mutants highlight candidate dopamine- and cocaine-selective domains. Mol Pharmacol 58:1581–1592
Little KY, Elmer LW, Zhong H, Scheys JO, Zhang L (2002) Cocaine induction of dopamine transporter trafficking to the plasma membrane. Mol Pharmaocl 61:436–445
Loland CJ, Norregaard L, Litman T, Gether U (2002) Generation of an activating Zn2+ switch in the dopamine transporter: mutation of an intracellular tyrosine constitutively alters the conformational equilibrium of the transport cycle. Proc Natl Acad Sci USA 99:1683–1688
Loo DD, Eskandari S, Boorer KJ, Sarkar HK, Wright EM (2000) Role of Cl− in electrogenic Na+-coupled cotransporters GAT1 and SGLT1. J Biol Chem 275:37414–37422
Maiya R, Buck KJ, Harris RA, Mayfield RD (2002) Ethanol-sensitive sites on the human dopamine transporter. J Biol Chem 277:30724–30729
Morrow JA, Collie IT, Dunbar DR, Walker GB, Shahid M, Hill DR (1998) Molecular cloning and functional expression of the human glycine transporter GlyT2 and chromosomal localisation of the gene in the human genome. FEBS Lett 439:334–340
Nash SR, Giros B, Kingsmore SF, Rochelle JM, Suter ST, Gregor P, Seldin MF, Caron MG (1994) Cloning, pharmacological characterization, and genomic localization of the human creatine transporter. Receptors Channels 2:165–174
Nelson N (1998) The family of Na+/Cl− neurotransmitter transporters. J Neurochem 71:1785–1803
Nelson H, Mandiyan S, Nelson N (1990) Cloning of the human brain GABA transporter. FEBS Lett 269:181–184
Olivier B, Soudijn W, Wijngaarden I van (2000) Serotonin, dopamine and norepinephrine transporters in the central nervous system and their inhibitors. Prog Drug Res 54:59–119
Pacholczyk T, Blakely RD, Amara SG (1991) Expression cloning of a cocaine- and antidepressant-sensitive human noradrenaline transporter. Nature 350:350–354
Patrylo PR, Spencer DD, Williamson A (2001) GABA uptake and heterotransport are impaired in the dentate gyrus of epileptic rats and humans with temporal lobe sclerosis. J Neurophysiol 85:1533–1542
Poyotos I, Ruberti F, Martinez-Maza R, Gimenez C, Dotti CG, Zafra F (2000) Polarized distribution of glycine transporter isoforms in epithelial and neuronal cells. Mol Cell Neurosci 15:99–111
Ramamoorthy S, Bauman AL, Moore KR, Han H, Yang-Feng T, Chang AS, Ganapathy V, Blakely RD (1993) Antidepressant- and cocaine-sensitive human serotonin transporters: molecular cloning, expression, and chromosomal localization. Proc Natl Acad Sci USA 90:2542–2546
Ramamoorthy S, Leibach FH, Mahesh VB, Han H, Yang-Feng T, Blakely RD, Ganapathy V (1994) Functional characterization and chromosomal localization of a cloned taurine transporter from human placenta. Biochem J 300:893–900
Rasola A, Galietta LJ. Barone V, Romeo G, Bagnasco S (1995) Molecular cloning and functional characterization of a GABA/betaine transporter from human kidney. FEBS Lett 373:229–233
Roubert C, Cox PJ, Bruss M, Hamon M, Bonisch H, Giros B (2001) Determination of residues in the norepinephrine transporter that are critical for tricyclic antidepressant affinity. J Biol Chem 276:8254–8260
Rudnick G, Clark J (1993) From synapse to vesicle: the reuptake and storage of biogenic amine neurotransmitters. Biochim Biophys Acta 1144:249–263
Saier MH Jr (1999) A functional-phylogenetic system for the classification of transport proteins. J Cell Biochem 32-33:84–94
Salomons GS, Dooren SJ van, Verhoeven NM, Cecil KM, Ball WS, Degrauw TJ, Jakobs C (2001) X-linked creatine-transporter gene (SLC6A8) defect: a new creatine-deficiency syndrome. Am J Hum Genet 68:1497–1500
Saransaari P, Oja SS (1999) Taurine release modified by nitric oxide-generating compounds in the developing and adult mouse hippocampus. Neuroscience 89:1103–1111
Saunders C, Ferrer JV, Shi L, Chen J, Merrill G, lamb M E, Leeb-Lundberg LMF, Carvelli L, Javitch JA, Galli A (2000) Amphetamine-induced loss of human dopamine transporter activity: an internalization-dependent and cocaine-sensitive mechanism. Proc Natl Acad Sci USA 97:6850–6855
Schmid JA, Scholze P, Kudlacek O, Freissmuth M, Singer E, Sitte HH (2001) Oligomerization of the human serotonin transporter and of the rat GABA transporter 1 visualized by fluorescence resonance energy transfer microscopy in living cells. J Biol Chem 276:3805–3810
Schroeter S, Apparsundaram S, Wiley RG, Miner LH, Sesack SR, Blakely RD (2000) Immunolocalization of the cocaine- and antidepressant-sensitive l-norepinephrine transporter. J Comp Neurol 420:211–232
Schwartz EA (1987) Depolarization without calcium can release γ-aminobutyric acid from a retinal neuron. Science 238:350–355
Shafqat S, Velaz-Faircloth M, Henzi VA, Whitney KD, Yang-Feng TL, Seldin MF, Fremeau RT (1995) Human brain-specific L-proline transporter: molecular cloning, functional expression, and chromosomal localization of the gene in the human and mouse genomes. Mol Pharmacol 48:219–229
Shannon JR, Flattem NL, Jordan J, Jacob G, Black BK, Biaggioni I, Blakely RD, Robertson D (2000) Orthostatic intolerance and tachycardia associated with norepinephrine-transporter deficiency. N Engl J Med 342:541–549
Sloan JL, Mager S (1999) Cloning and functional expression of a human Na+ and Cl−-dependent neutral and cationic amino acid transporter B0+. J Biol Chem 274:23740–23745
Sloan JL, Grubb BR, Mager S (2003) Expression of the amino acid transporter ATB0+ in lung: possible role in luminal protein removal. Am J Physiol 284:L39–L49
Soudijn W, Wijngaarden I van (2000) The GABA transporter and its inhibitors. Curr Med Chem 7:1063–1079
Sturman JA (1990) Taurine deficiency. Prog Clin Biol Res 351:385–395
Sundman-Eriksson I, Blennow K, Davidsson P, Dandenell AK, Marcusson J (2002) Increased [3H]tiagabine binding to GAT-1 in the cingulate cortex in schizophrenia. Neuropsychobiology 45:7-11
Sung U, Apparsundaram S, Galli A, Kahlig KM, Savchenko V, Schroeter S, Quick MW, Blakely RD (2003) A regulated interaction of syntaxin 1A with the antidepressant-sensitive norepinephrine transporter establishes catecholamine clearance capacity. J Neurosci 23:1697–709
Supplisson S, Roux MJ (2002) Why glycine transporters have different stoichiometries. FEBS Lett 529:93–101
Takeuchi K, Toyohara H, Sakaguchi M (2000) A hyperosmotic stress-induced mRNA of carp cell encodes Na+- and Cl−-dependent high affinity taurine transporter. Biochim Biophys Acta 1464:219–230
Torres GE, Yao W-D, Mohn AR, Quan H, Kim K-M, Levey AI, Staudinger J, Caron MG (2001) Functional interaction between monoamine plasma membrane transporters and synaptic PDZ domain-containing protein PICK1. Neuron 30:121–134
Torres GE, Carneiro A, Seamans K, Fiorentini C, Sweeney A, Yao W-D, Caron MG (2003) Oligomerization and trafficking of the human dopamine transporter. J Biol Chem 278:2731–2739
Uhl GR, Hall FS, Sora I (2002) Cocaine, reward, movement and monoamine transporters. Mol Psychiatry 7:21–26
Van Winkle LJ (2001) Amino acid transport regulation and early embryo development. Biol Reprod 1:1–12
Whitworth TL, Quick MW (2001) Substrate-induced regulation of γ-aminobutyric acid (GABA) transporter trafficking requires tyrosine phosphorylation. J Biol Chem 276:42932–42937
Xu F, Gainetdinov RR, Wetsel WC, Jones SR, Bohn LM, Miller GW, Wang YM, Caron MG (2000) Mice lacking the norepinephrine transporter are supersensitive to psychostimulants. Nat Neurosci 3:465–471
Zahniser NR, Doolen S (2001) Chronic and acute regulation of Na+/Cl−-dependent neurotransmitter transporters: drugs, substrates, presynaptic receptors, and signaling systems. Pharmacol Ther 92:21–55
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This work was supported in part by National Institutes of Health Grants DA11978, DA13261 to MEAR, and DA10509, MH61468 to MWQ.
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Chen, NH., Reith, M.E.A. & Quick, M.W. Synaptic uptake and beyond: the sodium- and chloride-dependent neurotransmitter transporter family SLC6. Pflugers Arch - Eur J Physiol 447, 519–531 (2004). https://doi.org/10.1007/s00424-003-1064-5
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DOI: https://doi.org/10.1007/s00424-003-1064-5