Subcellular Redistribution of the Serotonin Transporter by Secretory Carrier Membrane Protein 2

Abstract

The serotonin transporter (SERT) belongs to the SLC6 family of sodium- and chloride-dependent neurotransmitter transporters responsible for uptake of amino acids and biogenic amines from extracellular spaces. Their activities and subcellular distributions are regulated by various cellular mechanisms, including interactions with other proteins. Using the yeast two-hybrid approach we screened a human brain cDNA library and identified secretory carrier membrane protein 2 (SCAMP2) as a novel SERT-interacting protein. GST-pulldown assays confirmed the physical interaction between SCAMP2 and the N-terminal domain of SERT. In addition, SERT was found to form a complex with SCAMP2 as demonstrated by co-immunoprecipitation from a heterologous expression system and from rat brain homogenate. Co-expression of SERT and SCAMP2 in mammalian cells results in the subcellular redistribution of SERT with a decrease in cell surface SERT and a concomitant reduction in 5-HT uptake activity. Using confocal microscopy we show that in neuronal cells endogenous SERT co-localizes with SCAMP2 in discrete structures also containing the lipid raft marker flotillin-1 and the SNARE protein syntaxin 1A. In contrast, SERT immunoreactivity is clearly segregated from transferrin receptor-containing endosomes. A single amino acid mutation, cysteine-201 to alanine, within the conserved cytoplasmic E peptide of SCAMP2, abolished SCAMP2-mediated down-regulation of SERT, although this mutation had no effect on the physical interaction between SERT and SCAMP2. Taken together, our results suggest that SCAMP2 plays an important role in the regulation of the subcellular distribution of SERT. The serotonin transporter (SERT) belongs to the SLC6 family of sodium- and chloride-dependent neurotransmitter transporters responsible for uptake of amino acids and biogenic amines from extracellular spaces. Their activities and subcellular distributions are regulated by various cellular mechanisms, including interactions with other proteins. Using the yeast two-hybrid approach we screened a human brain cDNA library and identified secretory carrier membrane protein 2 (SCAMP2) as a novel SERT-interacting protein. GST-pulldown assays confirmed the physical interaction between SCAMP2 and the N-terminal domain of SERT. In addition, SERT was found to form a complex with SCAMP2 as demonstrated by co-immunoprecipitation from a heterologous expression system and from rat brain homogenate. Co-expression of SERT and SCAMP2 in mammalian cells results in the subcellular redistribution of SERT with a decrease in cell surface SERT and a concomitant reduction in 5-HT uptake activity. Using confocal microscopy we show that in neuronal cells endogenous SERT co-localizes with SCAMP2 in discrete structures also containing the lipid raft marker flotillin-1 and the SNARE protein syntaxin 1A. In contrast, SERT immunoreactivity is clearly segregated from transferrin receptor-containing endosomes. A single amino acid mutation, cysteine-201 to alanine, within the conserved cytoplasmic E peptide of SCAMP2, abolished SCAMP2-mediated down-regulation of SERT, although this mutation had no effect on the physical interaction between SERT and SCAMP2. Taken together, our results suggest that SCAMP2 plays an important role in the regulation of the subcellular distribution of SERT. The serotonin transporter (SERT) 2The abbreviations used are: SERT, serotonin transporter; SCAMP, secretory carrier membrane protein; 5-HT, 5-hydroxytryptamine; DAT, dopamine transporter; NET, norepinephrine transporter; GAT, γ-aminobutyric acid transporter; GLYT, glycine transporter; PKC, protein kinase C; TfR, transferrin receptor; GST, glutathione S-transferase; CHAPS, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid; PBS, phosphate-buffered saline; HEK, human embryonic kidney. is an integral plasma membrane glycoprotein that regulates serotoninergic neurotransmission through the reuptake of 5-hydroxytryptamine (5-HT, serotonin) from the synapse. SERT is of particular clinical and pharmacological interest as it has been implicated in a variety of neuropsychiatric disorders, as well as several dysfunctions in the periphery (1Murphy D.L. Lerner A. Rudnick G. Lesch K.P. Mol. Interv. 2004; 4: 109-123Crossref PubMed Scopus (357) Google Scholar). It is the primary target for a number of widely prescribed antidepressants and is also the site of action for drugs of abuse (2Schloss P. Williams D.C. J. Psychopharmacol. 1998; 12: 115-121Crossref PubMed Scopus (225) Google Scholar, 3Iversen L. Mol. Psychiatry. 2000; 5: 357-362Crossref PubMed Scopus (129) Google Scholar), including methylenedioxymethamphetamine (MDMA, “ecstasy”) and cocaine (4Rudnick G. Wall S.C. Proc. Natl. Acad. Sci. U. S. A. 1992; 89: 1817-1821Crossref PubMed Scopus (406) Google Scholar, 5Rudnick G. Wall S.C. Mol. Pharmacol. 1991; 40: 421-426PubMed Google Scholar). SERT belongs to the SLC6 family of sodium- and chloride-dependent neurotransmitter transporters, which also include for example transporters for dopamine (DAT), norepinephrine (NET), γ-aminobutyric acid (GAT), and glycine (GLYT1 and GLYT2) (6Chen N.H. Reith M.E. Quick M.W. Pflugers Arch. 2004; 447: 519-531Crossref PubMed Scopus (338) Google Scholar). These transporters share a number of structural features, such as 12 membrane-spanning domains, a large extracellular loop containing multiple glycosylation sites and cytoplasmic N and C termini. The transport capacity of neurotransmitter transporters is influenced both by the number of transporter molecules present at the cell surface and by the intrinsic activity of individual transporter molecules (7Blakely R.D. Bauman A.L. Curr. Opin. Neurobiol. 2000; 10: 328-336Crossref PubMed Scopus (222) Google Scholar, 8Robinson M.B. J. Neurochem. 2002; 80: 1-11Crossref PubMed Scopus (175) Google Scholar). For instance, SERT is known to undergo acute down-regulation in response to activation of protein kinase C (PKC) (9Qian Y. Galli A. Ramamoorthy S. Risso S. DeFelice L.J. Blakely R.D. J. Neurosci. 1997; 17: 45-57Crossref PubMed Google Scholar). This down-regulation involves the redistribution of the transporter from the plasma membrane to intracellular compartments. In contrast, protein kinase G (PKG) activation has been shown to cause an up-regulation of both SERT activity and SERT cell surface abundance (10Zhu C.B. Hewlett W.A. Feoktistov I. Biaggioni I. Blakely R.D. Mol. Pharmacol. 2004; 65: 1462-1474Crossref PubMed Scopus (142) Google Scholar). Accumulating evidence suggest that the subcellular distribution of neurotransmitter transporters is also regulated through direct interaction with specific proteins. For example, the t-SNARE protein syntaxin 1A is involved in the trafficking and PKC-dependent regulation of SERT and related transporters (11Beckman M.L. Bernstein E.M. Quick M.W. J. Neurosci. 1998; 18: 6103-6112Crossref PubMed Google Scholar, 12Quick M.W. Neuron. 2003; 40: 537-549Abstract Full Text Full Text PDF PubMed Scopus (135) Google Scholar, 13Geerlings A. Nunez E. Lopez-Corcuera B. Aragon C. J. Biol. Chem. 2001; 276: 17584-17590Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar, 14Sung U. Apparsundaram S. Galli A. Kahlig K.M. Savchenko V. Schroeter S. Quick M.W. Blakely R.D. J. Neurosci. 2003; 23: 1697-1709Crossref PubMed Google Scholar). In addition, the monoamine transporters SERT, DAT, and NET exist in signaling complexes containing the catalytic subunit of protein phosphatase 2A, an interaction that is destabilized by activation of PKC (15Bauman A.L. Apparsundaram S. Ramamoorthy S. Wadzinski B.E. Vaughan R.A. Blakely R.D. J. Neurosci. 2000; 20: 7571-7578Crossref PubMed Google Scholar). The yeast two-hybrid approach has been used to identify several proteins that interact with the cytoplasmic domains of the monoamine transporters. For instance, the PKC substrate MacMARCKS was isolated as a binding partner of the C terminus of SERT (16Jess U. El Far O. Kirsch J. Betz H. Biochem. Biophys. Res. Commun. 2002; 294: 272-279Crossref PubMed Scopus (40) Google Scholar). Another PKC substrate, the PDZ domain-containing protein PICK1 was found to interact with the C terminus of monoamine transporters and seems to enhance their cell surface expression (17Torres G.E. Yao W.D. Mohn A.R. Quan H. Kim K.M. Levey A.I. Staudinger J. Caron M.G. Neuron. 2001; 30: 121-134Abstract Full Text Full Text PDF PubMed Scopus (279) Google Scholar). Using the yeast two-hybrid approach to search for novel serotonin transporter interacting proteins we have identified several proteins that appear to affect the subcellular distribution of SERT. Here we report the identification and characterization of SCAMP2 as a novel SERT-binding protein. SCAMP2 belongs to a family of proteins that function as carriers to the cell surface in post-Golgi recycling pathways (18Brand S.H. Castle J.D. EMBO J. 1993; 12: 3753-3761Crossref PubMed Scopus (78) Google Scholar, 19Brand S.H. Laurie S.M. Mixon M.B. Castle J.D. J. Biol. Chem. 1991; 266: 18949-18957Abstract Full Text PDF PubMed Google Scholar, 20Singleton D.R. Wu T.T. Castle J.D. J. Cell Sci. 1997; 110: 2099-2107Crossref PubMed Google Scholar). SCAMPs are integral membrane proteins containing four transmembrane helices. Highly conserved regions include a small segment between transmembrane helices 2 and 3, the so-called E peptide, which has been shown to play a critical role for the function of SCAMP2 (21Hubbard C. Singleton D. Rauch M. Jayasinghe S. Cafiso D. Castle D. Mol. Biol. Cell. 2000; 11: 2933-2947Crossref PubMed Scopus (44) Google Scholar). Our data are consistent with a role for SCAMP2 in the regulation of the subcellular distribution of SERT. Reagents—The polyclonal goat C-20 antibody (Santa Cruz Biotechnology), recognizing the C-terminal domain of SERT was used for the detection of SERT by Western blotting as well as for co-immunoprecipitation from transfected HEK-293 cells. For co-immunoprecipitation from rat brain homogenates a polyclonal rabbit the extracellular loop of SERT, G. S. and was found to This was by of For confocal microscopy the a antibody which was a used on the with other used in a particular used goat (Santa Cruz Biotechnology), as well as 1A and both from from from from the yeast two-hybrid system as by the cDNA N-terminal and C-terminal domains of by and with the domain in and the yeast the was with the yeast with a human brain cDNA library in the yeast cells on and on for activity and from interacting proteins from yeast cells and cells. The of the by and the for data the search Cell and embryonic cells at in with 2 and cells PubMed Scopus Google by of of at in containing and to the and cells For was used to cells to in a and was isolated to the was with to cDNA cDNA was from of and and by specific and of was from human and the M. M.B. O. Res. Mol. Res. PubMed Scopus Google Scholar). the cDNA SCAMP2, cDNA was from isolated from HEK-293 cells and to containing The was with and the mammalian expression in the at and the system The of was by Western by transfected HEK-293 cells with in 2 for at by at for with and by and to with in and and with the primary goat goat flotillin-1 1A by with the antibody antibody Western blotting substrate and for at with in and with of rat brain was in of to which a was was at for and the was at for at The was in containing and for at the was at for at and the was and used for and assays to the N-terminal domain of the C-terminal domain of and the N-terminal domain of to by the expression The proteins in E. and with at for proteins by and by of to with of protein in from transfected HEK-293 cells. The was in and proteins in For co-immunoprecipitation assays on transfected HEK-293 of protein in was with of goat of on rat brain was by of protein with of of rabbit for 2 at by with protein (Santa Cruz at with and proteins in cells in and transfected and The cells for a uptake was was from the cells by and the cells with 2 and in for at The uptake was at and by the of and by of containing with and was a uptake was by the of in the of the by Cell cells in containing and and in in on for with The cells with glycine in and for a in on The cells in in in and with for at in and proteins in an of by Western blotting and with by rat brain was to in in the of by a The was at for at The was in containing and for at The was at for at to cell The was with an of in an and with of and of The for at in a a of from the of the and for Western cells transfected HEK-293 cells on to in and with in PBS, for at was with for with in at by with primary antibody in for at in and with the antibody in for at the cells in 2 in on a confocal HEK-293 cells with goat and rabbit cells with rabbit and goat used at a of used as for SERT, for SCAMP2, was used for marker used at a of of SCAMP2 as a SERT-binding search for novel SERT-interacting we several yeast two-hybrid with a human brain cDNA library the cytoplasmic domains of human SERT as A number of SCAMP2 The physical interaction between SCAMP2 and the N-terminal domain of SERT was confirmed by in which a protein of and the N-terminal domain of SERT a C-terminal of SERT to SCAMP2 from transfected HEK-293 cells In addition, we found that SCAMP2 also with the N-terminal domain of to the interaction between SCAMP2 and SERT. in transfected HEK-293 cells the shown in SCAMP2 with SERT in from cells both SERT and SCAMP2, was in from cells SCAMP2 that endogenous SCAMP2 and SERT also in rat brain from rat brain and the was with shown in SCAMP2 with SERT no proteins of SCAMP2 a of 5-HT in HEK-293 from a of effect of SCAMP2 on 5-HT uptake was in HEK-293 cells. SCAMP2 is at in HEK-293 and from this cell was in used in our to the cDNA for SCAMP2 Using we have shown that cells also small of of SCAMP2 in a with SERT 5-HT uptake activity was by SCAMP2 in a The expression of SCAMP2 affect the of SERT as by Western blotting In cells transfected with SCAMP2 and SERT a of 5-HT uptake activity was by an of with cells SERT are cells in cells SERT cells in cells SERT and in the for 5-HT transport in cells SERT in cells SERT and the decrease in in the of SCAMP2 is by in the number of transporter molecules on the cell we cell surface on transfected HEK-293 cells. proteins of cells transfected with SERT in with SCAMP2 with the membrane and proteins with of protein and protein and to the of protein by Western blotting the antibody by and the of SERT the used for SERT was cell surface and intracellular protein was on in a of with SCAMP2, the distribution of SERT to a of cell surface intracellular protein. cell surface SERT protein was by of transporter molecules also an in intracellular protein to the of this was it which is by the small to for that no intracellular proteins with SCAMPs shown to at to a to the plasma membrane L. Cafiso D. Castle D. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google Scholar), we to SCAMP2 the used This of the that the extracellular domains are for the of SCAMP2 to the cell surface is A. Castle D. J. Cell Sci. PubMed Scopus Google Scholar, S.M. G.E. Castle J.D. J. Biol. Chem. 1993; Full Text PDF PubMed Google Scholar). The reduction in SERT on the cell surface well with the in SERT uptake that SCAMP2 effect by a redistribution of SERT. SERT and SCAMP2 in HEK-293 microscopy was used to the subcellular of SERT and SCAMP2 in HEK-293 cells In cells transfected with SERT the transporter with endogenous SCAMP2 both at the cell surface in structures and in intracellular compartments. SCAMP2 in the of SERT, SCAMP2 an distribution to the protein. In cells both SERT and SCAMP2, SERT with SCAMP2 in intracellular it that the of SERT at the cell surface is this in distribution from confocal microscopy and is by cell surface as demonstrated in the the between SERT and SCAMP2 a direct role for SCAMP2 in the subcellular distribution of SERT. The intracellular of SERT and SCAMP2 to the with the transferrin a marker of the recycling on cells SERT and SCAMP2 and SERT with SCAMP2, was with the which a the In SERT to with SCAMP2 in discrete intracellular structures that are from endosomes. SERT with SCAMP2 in the between SERT and SCAMP2 we the endogenous distribution of SERT and SCAMP2 in an serotoninergic rat cell PubMed Scopus Google Scholar). endogenous expression of SCAMP2 as well as and in cells by confocal microscopy demonstrated of SERT and SCAMP2 in discrete structures the plasma membrane and in intracellular the of SERT and SCAMP2 with with HEK-293 we found with the for the marker the distribution and of SCAMP2 and SERT to in neuronal cells and HEK-293 cells. In both proteins also show with a used marker for the In contrast, the lipid raft marker flotillin-1 with SERT in syntaxin which has been shown to interact with SERT M.W. Neuron. 2003; 40: 537-549Abstract Full Text Full Text PDF PubMed Scopus (135) Google Scholar, J. Williams C. Biochem. 2001; PubMed Google and to with SCAMP2 in cells L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google Scholar), also with SERT and SCAMP2. to SERT, SCAMP2 in that SERT is present in membrane domains, so-called lipid S. Williams C. J. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). The of SCAMP2 with SERT and the lipid raft marker flotillin-1 that SCAMP2 also with membrane the of SCAMP2 with lipid rat brain was and in and through a membrane and their proteins to the of the proteins in the flotillin-1 was found in the raft (1Murphy D.L. Lerner A. Rudnick G. Lesch K.P. Mol. Interv. 2004; 4: 109-123Crossref PubMed Scopus (357) Google Scholar, P. Williams D.C. J. Psychopharmacol. 1998; 12: 115-121Crossref PubMed Scopus (225) Google Scholar, 3Iversen L. Mol. Psychiatry. 2000; 5: 357-362Crossref PubMed Scopus (129) Google Scholar), the protein was present in to that this raft from proteins SERT and syntaxin 1A found in our SCAMP2 was also in raft the that SERT and SCAMP2 in domains within cellular the Highly E of SCAMP2 for the of the of the we to identify individual within SCAMP2, which are involved in the regulation of SERT. The conserved structural segment within the family is the so-called E peptide, which is at the cytoplasmic membrane surface the and transmembrane domain (21Hubbard C. Singleton D. Rauch M. Jayasinghe S. Cafiso D. Castle D. Mol. Biol. Cell. 2000; 11: 2933-2947Crossref PubMed Scopus (44) Google Scholar). This segment has been demonstrated to play a critical role at a in in L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google and cells L. Cafiso D. Castle D. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). of within the E peptide, and the of SCAMP2 to L. Cafiso D. Castle D. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). to are involved in the SCAMP2-mediated down-regulation of SERT. this we single amino acid and co-immunoprecipitation from HEK-293 cells transfected with SERT in with Using the antibody we to both the and the that the binding of SCAMP2 to SERT. the of the on 5-HT uptake activity in HEK-293 cells the to SCAMP2, a decrease in of with the cells in cells SERT cells in cells SERT in with SCAMP2 and cells in cells SERT with of the had no effect on 5-HT uptake a to the no in of the SCAMP2, the was found to at we a in expression SCAMP2 and the protein This that the of the to 5-HT uptake is of a reduction of protein an function of SCAMP2. confirmed that the was to the cell surface expression of SERT and results that a single amino acid in SCAMP2 the effect of SCAMP2 on SERT function the interaction with SERT. Here we report the identification of SCAMP2 as a novel SERT-interacting protein that the subcellular of the SCAMP2 belongs to a family of proteins that are of the cell surface recycling SCAMPs are and are found on secretory involved in regulated on recycling that to and from the plasma membrane and also on (18Brand S.H. Castle J.D. EMBO J. 1993; 12: 3753-3761Crossref PubMed Scopus (78) Google Scholar, 19Brand S.H. Laurie S.M. Mixon M.B. Castle J.D. J. Biol. Chem. 1991; 266: 18949-18957Abstract Full Text PDF PubMed Google Scholar, A. Castle D. J. Cell Sci. PubMed Scopus Google Scholar, J. Cell Biol. PubMed Scopus Google Scholar). SCAMP2 with SERT both in a heterologous expression system and in rat brain SCAMP2 to the N-terminal domain of SERT and also to the domain of DAT, that the interaction with SCAMP2 is a of monoamine transporters. of SCAMP2 with SERT in HEK-293 cells results in a down-regulation of 5-HT uptake in a a reduction in no reduction in protein the of of protein in the heterologous expression system we This is by the that the SCAMP2 although at as SCAMP2 affect SERT the reduction in 5-HT uptake well with the cellular redistribution of SERT as by cell surface and confocal In neuronal cells endogenous SERT in compartments. In as well as in HEK-293 SERT and SCAMP2 with with the marker Our data are in with a by Castle and in which SCAMP2 with and with in cells A. Castle D. J. Cell Sci. PubMed Scopus Google Scholar). SCAMPs are with recycling that through the interaction with SCAMP2, SERT to a recycling in HEK-293 cells the effect of SCAMP2 on the subcellular distribution of SERT and the decrease in 5-HT uptake activity the of transporter molecules intracellular compartments. Our that the lipid raft marker the that structures recycling as such have been shown to in lipid raft including J. Mol. Biol. Cell. 2000; 11: PubMed Scopus Google Scholar). in our that SERT is with lipid in a S. Williams C. J. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). found that lipid SERT from both cell surface and intracellular that lipid also play an important role in the subcellular distribution of SERT. This is in the as we show that SCAMP2 is also present in the complex within intracellular membrane has been identified to a in mammalian cells Cell Biol. PubMed Scopus Google Scholar). In this it is to that the norepinephrine transporter to undergo in a and lipid Ramamoorthy S. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus (129) Google Scholar). also found that the immunoreactivity with syntaxin 1A in cells. which is a in has been shown to a number of neurotransmitter transporters, which has to the that neurotransmitter and reuptake are M.L. L. Quick M.W. Neurosci. 2000; PubMed Scopus (135) Google Scholar). for the with syntaxin 1A is that the intracellular structures a of which are involved in plasma membrane protein recycling neurotransmitter 1A is known to with C. J. L. J. Cell Biol. PubMed Scopus Google Scholar). the in a that to neurotransmitter transporters in for example was shown to present on that also the marker as well as syntaxin 1A A. Nunez E. Lopez-Corcuera B. Aragon C. J. Biol. Chem. 2001; 276: 17584-17590Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar). In addition, was found to to and from the plasma membrane in a and as D. Quick M.W. J. Neurosci. 2003; 23: PubMed Google Scholar). in particular in appear to to the plasma their with syntaxin 1A SNARE sites for recycling This is by a that in cells SCAMP2 with at it co-localizes with syntaxin 1A in the plasma membrane L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google Scholar, L. H. Castle A. J. J. G. Castle D. Mol. Biol. Cell. PubMed Google Scholar). The intracellular of SERT as a of SCAMP2 from an in the for a decrease in the of is to function in both and M. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, G. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). In addition, a number of evidence for a role of in particular SCAMP2, in regulated L. Cafiso D. Castle D. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google Scholar, L. H. Castle A. J. J. G. Castle D. Mol. Biol. Cell. PubMed Google Scholar). SCAMP2 has been as a protein for SNARE complexes to secretory and to function in through direct interaction with and L. H. Castle A. J. J. G. Castle D. Mol. Biol. Cell. PubMed Google Scholar). In particular the E peptide to have an function in a in regulated and within the E peptide found to critical for this L. Cafiso D. Castle D. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google Scholar). In the present a mutation in the SCAMP2-mediated decrease in 5-HT uptake as well as the reduction in cell surface of SERT. we found that this is for the interaction of the that the binding of SCAMP2 to SERT is to transporter activity. SCAMP2 appear to with the 5-HT transport and the SCAMP2-mediated of action is clearly from the effect of syntaxin 1A on SERT and related transporters M.W. Neuron. 2003; 40: 537-549Abstract Full Text Full Text PDF PubMed Scopus (135) Google Scholar, 14Sung U. Apparsundaram S. Galli A. Kahlig K.M. Savchenko V. Schroeter S. Quick M.W. Blakely R.D. J. Neurosci. 2003; 23: 1697-1709Crossref PubMed Google Scholar, M.L. L. Quick M.W. Neurosci. 2000; PubMed Scopus (135) Google Scholar). the mutation of which was found to for the regulation of L. Castle A. Castle D. Mol. Biol. Cell. 2002; PubMed Scopus Google Scholar), the SCAMP2 effect on SERT activity. we the of SCAMP2 in a cell the role of the E peptide on was in and which regulated secretory the that SCAMP2 also the regulated of SERT to the cell surface in for example neurotransmitter is and an in is are to this on our results in HEK-293 cells and our that is for SERT regulation by SCAMP2, we that the role of SCAMP2 in the cellular distribution of SERT is from role in in secretory cells. are to the SCAMP2-mediated redistribution of SERT is a of for and SCAMP2 plays a role in the down-regulation of the for the and for of this antibody for confocal also and for critical of the