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J Biol Chem
2011 Oct 28;28643:37874-86. doi: 10.1074/jbc.M111.289330.
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The large extracellular loop of organic cation transporter 1 influences substrate affinity and is pivotal for oligomerization.
Keller T
,
Egenberger B
,
Gorboulev V
,
Bernhard F
,
Uzelac Z
,
Gorbunov D
,
Wirth C
,
Koppatz S
,
Dötsch V
,
Hunte C
,
Sitte HH
,
Koepsell H
.
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Polyspecific organic anion transporters (OATs) and organic cation transporters (OCTs) of the SLC22 transporter family play a pivotal role in absorption, distribution, and excretion of drugs. Polymorphisms in these transporters influence therapeutic effects. On the basis of functional characterizations, homology modeling, and mutagenesis, hypotheses for how OCTs bind and translocate structurally different cations were raised, assuming functionally competent monomers. However, homo-oligomerization has been described for OATs and OCTs. In the present study, evidence is provided that the large extracellular loops (EL) of rat Oct1 (rOct1) and rat Oat1 (rOat1) mediate homo- but not hetero-oligomerization. Replacement of the cysteine residues in the EL of rOct1 by serine residues (rOct1(6ΔC-l)) or breaking disulfide bonds with dithiothreitol prevented oligomerization. rOct1 chimera containing the EL of rOat1 (rOct1(rOat1-l)) showed oligomerization but reduced transporter amount in the plasma membrane. For rOct1(6ΔC-l) and rOct1(rOat1-l), similar K(m) values for 1-methyl-4-phenylpyridinium(+) (MPP(+)) and tetraethylammonium(+) (TEA(+)) were obtained that were higher compared with rOct1 wild type. The increased K(m) of rOct1(rOat1-l) indicates an allosteric effect of EL on the cation binding region. The similar substrate affinity of the oligomerizing and non-oligomerizing loop mutants suggests that oligomerization does not influence transport function. Independent transport function of rOct1 monomers was also demonstrated by showing that K(m) values for MPP(+) and TEA(+) were not changed after treatment with dithiothreitol and that a tandem protein with two rOct1 monomers showed about 50% activity with unchanged K(m) values for MPP(+) and TEA(+) when one monomer was blocked. The data help to understand how OCTs work and how mutations in patients may affect their functions.
Arndt,
Interaction of cations, anions, and weak base quinine with rat renal cation transporter rOCT2 compared with rOCT1.
2001, Pubmed,
Xenbase
Arndt,
Interaction of cations, anions, and weak base quinine with rat renal cation transporter rOCT2 compared with rOCT1.
2001,
Pubmed
,
Xenbase
Bartholomäus,
Glycine transporter dimers: evidence for occurrence in the plasma membrane.
2008,
Pubmed
Brosig,
The dimerization motif of the glycophorin A transmembrane segment in membranes: importance of glycine residues.
1998,
Pubmed
Busch,
Monoamine neurotransmitter transport mediated by the polyspecific cation transporter rOCT1.
1996,
Pubmed
,
Xenbase
Ciarimboli,
Regulation of organic cation transport.
2005,
Pubmed
Duan,
Transmembrane peptide as potent inhibitor of oligomerization and function of human organic anion transporter 1.
2011,
Pubmed
Farhan,
Oligomerization of neurotransmitter transporters: a ticket from the endoplasmic reticulum to the plasma membrane.
2006,
Pubmed
Feige,
PixFRET, an ImageJ plug-in for FRET calculation that can accommodate variations in spectral bleed-throughs.
2005,
Pubmed
Gorboulev,
Selectivity of the polyspecific cation transporter rOCT1 is changed by mutation of aspartate 475 to glutamate.
1999,
Pubmed
,
Xenbase
Gorboulev,
Subtype-specific affinity for corticosterone of rat organic cation transporters rOCT1 and rOCT2 depends on three amino acids within the substrate binding region.
2005,
Pubmed
,
Xenbase
Gorbunov,
High-affinity cation binding to organic cation transporter 1 induces movement of helix 11 and blocks transport after mutations in a modeled interaction domain between two helices.
2008,
Pubmed
Gründemann,
Ethidium bromide staining during denaturation with glyoxal for sensitive detection of RNA in agarose gel electrophoresis.
1994,
Pubmed
Gründemann,
Drug excretion mediated by a new prototype of polyspecific transporter.
1994,
Pubmed
,
Xenbase
Hein,
Dynamics of receptor/G protein coupling in living cells.
2005,
Pubmed
Ho,
Site-directed mutagenesis by overlap extension using the polymerase chain reaction.
1989,
Pubmed
Hong,
Human organic anion transporter hOAT1 forms homooligomers.
2005,
Pubmed
Kamsteeg,
Detection of aquaporin-2 in the plasma membranes of oocytes: a novel isolation method with improved yield and purity.
2001,
Pubmed
,
Xenbase
Keller,
Cell free expression and functional reconstitution of eukaryotic drug transporters.
2008,
Pubmed
Keller,
Purification and functional reconstitution of the rat organic cation transporter OCT1.
2005,
Pubmed
Kilic,
Oligomerization of serotonin transporter and its functional consequences.
2000,
Pubmed
Klammt,
High level cell-free expression and specific labeling of integral membrane proteins.
2004,
Pubmed
Koepsell,
Polyspecific organic cation transporters: structure, function, physiological roles, and biopharmaceutical implications.
2007,
Pubmed
Koepsell,
Substrate recognition and translocation by polyspecific organic cation transporters.
2011,
Pubmed
Nies,
Organic cation transporters (OCTs, MATEs), in vitro and in vivo evidence for the importance in drug therapy.
2011,
Pubmed
Perry,
A three-dimensional model of human organic anion transporter 1: aromatic amino acids required for substrate transport.
2006,
Pubmed
,
Xenbase
Popp,
Amino acids critical for substrate affinity of rat organic cation transporter 1 line the substrate binding region in a model derived from the tertiary structure of lactose permease.
2005,
Pubmed
,
Xenbase
Rizwan,
Organic anion transporters of the SLC22 family: biopharmaceutical, physiological, and pathological roles.
2007,
Pubmed
Schmid,
Fluorescence resonance energy transfer in the study of cancer pathways.
2003,
Pubmed
Shu,
Effect of genetic variation in the organic cation transporter 1 (OCT1) on metformin action.
2007,
Pubmed
Sturm,
Identification of cysteines in rat organic cation transporters rOCT1 (C322, C451) and rOCT2 (C451) critical for transport activity and substrate affinity.
2007,
Pubmed
,
Xenbase
Sucic,
The N terminus of monoamine transporters is a lever required for the action of amphetamines.
2010,
Pubmed
,
Xenbase
Sweet,
Expression cloning and characterization of ROAT1. The basolateral organic anion transporter in rat kidney.
1997,
Pubmed
,
Xenbase
Valentin,
The transport modifier RS1 is localized at the inner side of the plasma membrane and changes membrane capacitance.
2000,
Pubmed
,
Xenbase
Veyhl,
Downregulation of the Na(+)- D-glucose cotransporter SGLT1 by protein RS1 (RSC1A1) is dependent on dynamin and protein kinase C.
2003,
Pubmed
,
Xenbase
Veyhl,
Cloning of a membrane-associated protein which modifies activity and properties of the Na(+)-D-glucose cotransporter.
1993,
Pubmed
,
Xenbase
Volk,
Five amino acids in the innermost cavity of the substrate binding cleft of organic cation transporter 1 interact with extracellular and intracellular corticosterone.
2009,
Pubmed
,
Xenbase
Xia,
Reliable and global measurement of fluorescence resonance energy transfer using fluorescence microscopes.
2001,
Pubmed
