{"gene":"SCAMP2","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":2002,"finding":"A synthetic peptide (E peptide: CWYRPIYKAFR) from the conserved cytoplasmic segment between transmembrane spans 2 and 3 of SCAMP2 potently inhibits exocytosis in permeabilized mast cells, acting at a very late step beyond Ca2+/ATP-dependent priming, directly associated with membrane fusion. SCAMP2 co-immunoprecipitates with SNARE proteins SNAP-23 and syntaxin 4 at the plasma membrane.","method":"Permeabilized cell exocytosis assay, peptide inhibition, co-immunoprecipitation, immunofluorescence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (permeabilized cell assay, CoIP, peptide structure-activity), replicated in two cell types","pmids":["12124380"],"is_preprint":false},{"year":2002,"finding":"SCAMP2 localizes to plasma membranes at putative docking/fusion sites with syntaxin1 and complexin in PC12 cells. Overexpression of SCAMP2 point mutants in the E peptide (but not wild-type SCAMP2) dose-dependently inhibits depolarization-induced and calcium-stimulated secretion; this inhibition is largely rescued by lysophosphatidylcholine, implicating SCAMP2 E peptide in fusion pore formation during granule exocytosis.","method":"Regulated overexpression of point mutants, amperometry, pharmacological rescue with lysophosphatidylcholine, confocal colocalization","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1-2 — dominant-negative mutagenesis with pharmacological rescue and functional readout","pmids":["12475951"],"is_preprint":false},{"year":2005,"finding":"SCAMP2 interacts with Arf6 and phospholipase D1 (PLD1) in PC12 cells; co-immunoprecipitation is enhanced after cell depolarization and GTPγS treatment. A SCAMP2-derived E peptide suppresses PLD activity. A SCAMP2 point mutant with decreased Arf6 association inhibits early membrane fusion events and fusion pore dilation, while mutant Arf6 deficient in PLD1 activation only inhibits early fusion events, placing SCAMP2 downstream of Arf6-PLD1 in exocytosis and specifically linking it to fusion pore formation.","method":"Co-immunoprecipitation, amperometry, dominant-negative mutants, peptide inhibition of PLD activity","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal CoIP, epistasis via double mutant analysis, functional amperometry readout","pmids":["16030257"],"is_preprint":false},{"year":2007,"finding":"SCAMP2 E peptide binds and sequesters PI(4,5)P2 within membranes through an electrostatic mechanism. EPR analysis shows R4 (R204 in full-length SCAMP2) is critical for PIP2 binding. Corresponding SCAMP2 point mutants (SC2-R204A, SC2-W202A) inhibit dense core vesicle exocytosis in PC12 cells, specifically decreasing fusion pore opening probability and stability of initially opened pores, establishing that SCAMP2-PIP2 interaction regulates fusion pore formation.","method":"EPR spectroscopy, NMR, alanine-scanning mutagenesis of full-length SCAMP2, amperometry in PC12 cells","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro biophysical assay (EPR, NMR) combined with mutagenesis and functional cell-based assay","pmids":["17713930"],"is_preprint":false},{"year":2006,"finding":"SCAMP2 interacts with the serotonin transporter (SERT) via yeast two-hybrid, GST pulldown, and co-immunoprecipitation from rat brain homogenate. Co-expression of SCAMP2 with SERT decreases cell-surface SERT and 5-HT uptake. SCAMP2 co-localizes with SERT in lipid raft/syntaxin 1A-containing structures. A single point mutation C201A in the SCAMP2 E peptide abolishes SCAMP2-mediated SERT downregulation without disrupting physical interaction, indicating the E peptide domain mediates the functional effect on trafficking.","method":"Yeast two-hybrid, GST pulldown, co-immunoprecipitation from brain homogenate, confocal microscopy, radioligand uptake assay, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including native brain tissue CoIP and mutagenesis dissecting physical vs. functional interaction","pmids":["16870614"],"is_preprint":false},{"year":2005,"finding":"SCAMP2 interacts with the C-terminus of NHE7 (organellar Na+/K+/H+ exchanger) identified by yeast two-hybrid; interaction confirmed by co-immunolocalization, co-immunoprecipitation, co-sedimentation in sucrose gradients, and in vitro binding. SCAMP2 binds NHE7 through a cytoplasmic TM2-TM3 loop (residues 184-208). Deletion of this loop or overexpression of the TM2-TM3 construct redistributes NHE7 from TGN to scattered recycling vesicles, indicating SCAMP2 participates in shuttling NHE7 between recycling vesicles and TGN.","method":"Yeast two-hybrid, co-immunoprecipitation, co-sedimentation, in vitro binding assay, deletion mutagenesis, confocal microscopy","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, domain mapping with deletion mutants and functional redistribution phenotype","pmids":["15840657"],"is_preprint":false},{"year":2009,"finding":"SCAMP2 binds directly to both the N- and C-terminal cytosolic extensions of the brain-enriched Na+/H+ exchanger NHE5, as shown by in vitro protein-protein interaction assays and co-immunoprecipitation. Co-expression of SCAMP2 (but not SCAMP5) increases NHE5 cell-surface abundance and transport activity. SCAMP2-specific N-terminal cytosolic domain is required for this effect. SCAMP2-mediated NHE5 surface targeting is reversed by dominant-negative Arf6 but not dominant-negative Rab11, placing SCAMP2 in an Arf6-dependent recycling endosome pathway.","method":"In vitro protein-protein interaction assay, co-immunoprecipitation, surface biotinylation, dominant-negative GTPase epistasis, confocal microscopy","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — in vitro direct binding, surface assay, and GTPase epistasis defining pathway position","pmids":["19276089"],"is_preprint":false},{"year":2011,"finding":"SCAMP2 interacts with the renal NKCC2 co-transporter identified by yeast two-hybrid and confirmed by co-immunoprecipitation and confocal co-localization. SCAMP2 overexpression decreases NKCC2 cell-surface abundance and transport activity by reducing exocytotic insertion (not endocytic retrieval), as shown by sodium 2-mercaptoethane sulfonate cleavage assay. The C201A E peptide mutation of SCAMP2 abolishes this regulation, indicating the E peptide domain mediates the effect on exocytotic trafficking.","method":"Yeast two-hybrid, co-immunoprecipitation, confocal microscopy, surface biotinylation, MesNa cleavage assay, site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods distinguishing exo- from endocytic mechanisms with mutagenesis","pmids":["21205824"],"is_preprint":false},{"year":2011,"finding":"SCAMP2 interacts with and regulates the dopamine transporter (DAT). DAT-SCAMP2 interaction is confirmed by co-immunoprecipitation and FRET microscopy. Co-expression of SCAMP2 with DAT reduces dopamine uptake and cell-surface DAT levels, mirroring its previously described effect on SERT.","method":"Co-immunoprecipitation, FRET microscopy, dopamine uptake assay, surface expression measurement","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2-3 — reciprocal CoIP and FRET, single lab, replicates prior SERT finding","pmids":["21295544"],"is_preprint":false},{"year":2008,"finding":"RNA interference-mediated knockdown of SCAMP2 in PC12 cells decreases the number and frequency of depolarization-induced dense core vesicle exocytotic events and delays the onset of exocytosis, as measured by amperometry. SCAMP2 knockdown also increases rapid fusion pore closure and decreases pore dilation without affecting upstream DCV distribution or calcium signaling, placing SCAMP2 specifically at the final membrane fusion step.","method":"siRNA knockdown, amperometry, calcium imaging","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 2 — clean loss-of-function with high-resolution functional readout (amperometry) distinguishing fusion pore dynamics from upstream events","pmids":["18171723"],"is_preprint":false},{"year":1997,"finding":"SCAMP1 and SCAMP2 extensively co-localize in post-Golgi recycling carrier membranes and can be co-immunoprecipitated, indicating they form protein complexes that may include homomultimers. Cross-linking studies suggest SCAMP1 forms homomultimers in situ.","method":"Co-immunoprecipitation, chemical cross-linking, immunocytochemistry, velocity centrifugation","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 3 — single-lab co-immunoprecipitation and crosslinking without functional consequence","pmids":["9224770"],"is_preprint":false},{"year":1997,"finding":"Three mammalian SCAMPs (1, 2, 3) are products of distinct genes with highly conserved sequences and extensively co-localize in post-Golgi recycling vesicles as shown by double-label immunofluorescence, suggesting shared function at the same vesicular transport sites rather than separate pathways.","method":"cDNA cloning, immunofluorescence double labeling, subcellular fractionation","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 3 — localization study with limited functional link","pmids":["9378760"],"is_preprint":false},{"year":1998,"finding":"SCAMP1 and SCAMP3, but not SCAMP2, are tyrosine phosphorylated in EGF-stimulated murine fibroblasts overexpressing EGFR. SCAMP3 phosphorylation is stimulated by EGFR in vitro, and EGF induces SCAMP-EGFR co-immunoprecipitation, suggesting phosphorylation is linked to EGFR internalization/downregulation. SCAMP2 is specifically excluded from this phosphorylation.","method":"In vitro kinase assay, co-immunoprecipitation, phosphatase treatment, vanadate inhibition","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro kinase assay and CoIP, but SCAMP2-specific finding is a negative result (not phosphorylated)","pmids":["9658162"],"is_preprint":false},{"year":2022,"finding":"SCAMP2 was identified as a novel Cav3.2 T-type calcium channel interacting protein. Co-expression of SCAMP2 with Cav3.2 in mammalian cells nearly abolishes whole-cell T-type current by reducing channel surface expression (evidenced by loss of intramembrane charge movement without reduction in total protein). Single amino acid mutations in the SCAMP2 E peptide partly reverse this effect. The downregulation also applies to Cav3.1 and Cav3.3 isoforms.","method":"Co-expression, whole-cell patch clamp, intramembrane charge movement recording, site-directed mutagenesis of E peptide","journal":"Molecular brain","confidence":"High","confidence_rationale":"Tier 2 — electrophysiology combined with charge movement analysis distinguishes trafficking from gating effects, plus mutagenesis","pmids":["34980194"],"is_preprint":false},{"year":2023,"finding":"SCAMP2 was identified as a novel interacting protein of the human sodium-dependent vitamin C transporter hSVCT1 by affinity pull-down proteomics and confirmed by co-immunoprecipitation. Co-expression of hSVCT1 and SCAMP2 leads to co-localization at intracellular structures and plasma membrane. Overexpression of SCAMP2 potentiates ascorbic acid uptake; knockdown of SCAMP2 decreases uptake. SCAMP2 knockdown also impairs hiPSC differentiation to neurons.","method":"Affinity tagging proteomics, co-immunoprecipitation, confocal microscopy, 14C-ascorbic acid uptake assay, siRNA knockdown, hiPSC neuronal differentiation","journal":"International journal of biological macromolecules","confidence":"Medium","confidence_rationale":"Tier 2-3 — CoIP plus functional uptake assay and knockdown phenotype, single lab","pmids":["36632962"],"is_preprint":false},{"year":2007,"finding":"SCAMP2 protein was identified by immunoelectron microscopy in platelet alpha-granule membranes, establishing its subcellular localization to this secretory organelle.","method":"Immunoelectron microscopy, sucrose gradient fractionation, mass spectrometry","journal":"Journal of thrombosis and haemostasis : JTH","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization by immunoelectron microscopy, no functional consequence established","pmids":["17723134"],"is_preprint":false}],"current_model":"SCAMP2 is a tetraspanning post-Golgi vesicle membrane protein that functions primarily in the late steps of regulated exocytosis via its conserved cytoplasmic E peptide domain, which interacts with PI(4,5)P2 and couples Arf6-stimulated PLD1 activity to fusion pore formation and dilation; it also regulates the surface trafficking of diverse membrane transporters (SERT, DAT, NHE5, NHE7, NKCC2, hSVCT1, Cav3.2) by controlling their exocytotic insertion into or retention at the plasma membrane through recycling endosome pathways."},"narrative":{"teleology":[{"year":1997,"claim":"Establishing SCAMP2 as a distinct gene product co-localizing with SCAMP1 and SCAMP3 in post-Golgi recycling vesicles provided the initial framework that SCAMPs function at shared vesicular transport sites and can form protein complexes.","evidence":"cDNA cloning, double-label immunofluorescence, co-immunoprecipitation, and chemical cross-linking in mammalian cells","pmids":["9224770","9378760"],"confidence":"Medium","gaps":["No functional consequence of SCAMP1-SCAMP2 interaction was demonstrated","Stoichiometry and composition of SCAMP complexes undefined","Role in vesicle trafficking inferred from localization only"]},{"year":2002,"claim":"Demonstrating that the SCAMP2 E peptide inhibits exocytosis at a step beyond Ca2+/ATP-dependent priming and that E peptide point mutants block secretion (rescuable by lysophosphatidylcholine) established SCAMP2 as a direct participant in fusion pore formation rather than upstream vesicle priming.","evidence":"Synthetic peptide inhibition in permeabilized mast cells, dominant-negative overexpression in PC12 cells with amperometry, pharmacological rescue, co-immunoprecipitation with SNAP-23/syntaxin 4","pmids":["12124380","12475951"],"confidence":"High","gaps":["Mechanism by which lysophosphatidylcholine bypasses SCAMP2 not fully resolved","Structural basis for E peptide–SNARE association unknown"]},{"year":2005,"claim":"Identification of SCAMP2 interaction with Arf6 and PLD1, and epistasis experiments showing SCAMP2 acts downstream of Arf6-PLD1 specifically at the fusion pore dilation step, positioned SCAMP2 within a defined signaling pathway controlling the final membrane merger event.","evidence":"Co-immunoprecipitation enhanced by depolarization/GTPγS, amperometry with SCAMP2 and Arf6 mutants, peptide-based PLD inhibition in PC12 cells","pmids":["16030257"],"confidence":"High","gaps":["Direct physical contact between SCAMP2 and PLD1 not shown with purified proteins","Whether PLD1-generated phosphatidic acid acts on SCAMP2 or independently on the pore is unclear"]},{"year":2005,"claim":"Discovery that SCAMP2 binds NHE7 through the TM2–TM3 cytoplasmic loop and controls NHE7 recycling between TGN and recycling vesicles extended SCAMP2 function beyond exocytosis to regulation of organellar transporter trafficking.","evidence":"Yeast two-hybrid, co-immunoprecipitation, in vitro binding, deletion mutagenesis with redistribution phenotype by confocal microscopy","pmids":["15840657"],"confidence":"High","gaps":["Directionality of SCAMP2 effect (anterograde vs. retrograde sorting of NHE7) not fully dissected","Physiological consequence of NHE7 mislocalization unknown"]},{"year":2006,"claim":"Showing that SCAMP2 binds SERT and reduces its surface expression through the E peptide domain—dissociating physical binding from functional regulation via the C201A mutation—established SCAMP2 as a trafficking regulator of neurotransmitter transporters.","evidence":"Yeast two-hybrid, GST pulldown, co-immunoprecipitation from rat brain, radioligand uptake, site-directed mutagenesis","pmids":["16870614"],"confidence":"High","gaps":["Whether SCAMP2 regulates SERT via exocytosis, endocytosis, or surface retention was not resolved","In vivo relevance of SCAMP2–SERT interaction in brain not tested"]},{"year":2007,"claim":"Biophysical demonstration that the E peptide binds and sequesters PI(4,5)P2 through R204, and that corresponding full-length SCAMP2 mutations impair fusion pore opening probability and stability, provided the first molecular mechanism for how SCAMP2 regulates membrane fusion—through local PIP2 sequestration.","evidence":"EPR spectroscopy and NMR on E peptide–lipid interactions, alanine-scanning mutagenesis with amperometry in PC12 cells","pmids":["17713930"],"confidence":"High","gaps":["Whether PIP2 sequestration and PLD1 coupling are mechanistically linked or parallel remains undefined","No structural model of E peptide within the bilayer at atomic resolution"]},{"year":2008,"claim":"Loss-of-function knockdown confirming that endogenous SCAMP2 is required for normal exocytotic event frequency, onset kinetics, and fusion pore dilation validated the gain-of-function mutant studies and established SCAMP2 as a necessary component of the exocytotic machinery.","evidence":"siRNA knockdown in PC12 cells with amperometry and calcium imaging","pmids":["18171723"],"confidence":"High","gaps":["Redundancy with other SCAMPs not evaluated by double knockdown","Effect on kiss-and-run versus full fusion not quantitatively separated"]},{"year":2009,"claim":"Demonstrating that SCAMP2 increases NHE5 surface expression through an Arf6-dependent (but Rab11-independent) recycling endosome pathway linked SCAMP2's transporter trafficking function to the same Arf6 axis involved in its exocytotic role.","evidence":"In vitro binding, co-immunoprecipitation, surface biotinylation, dominant-negative GTPase epistasis in heterologous cells","pmids":["19276089"],"confidence":"High","gaps":["Whether SCAMP2 acts as a cargo adaptor or a general fusion regulator in recycling endosomes is unresolved","Native neuronal validation lacking"]},{"year":2011,"claim":"Extension of SCAMP2's transporter regulatory repertoire to NKCC2 (reducing exocytotic insertion) and DAT (reducing surface levels) demonstrated the generality of E peptide–dependent surface trafficking control across functionally diverse cargo proteins.","evidence":"Yeast two-hybrid, co-immunoprecipitation, MesNa cleavage assay distinguishing exo- from endocytosis for NKCC2; CoIP and FRET for DAT","pmids":["21205824","21295544"],"confidence":"High","gaps":["Why SCAMP2 increases surface expression of some cargoes (NHE5, hSVCT1) but decreases others (SERT, DAT, NKCC2, Cav3.2) is mechanistically unexplained","Cargo selectivity determinants not mapped"]},{"year":2022,"claim":"Identification of SCAMP2 as a regulator of Cav3.2 T-type calcium channel surface expression—nearly abolishing current by blocking forward trafficking without reducing total protein—extended SCAMP2's E peptide–dependent trafficking control to ion channels.","evidence":"Whole-cell patch clamp, intramembrane charge movement recording, E peptide mutagenesis in heterologous expression system","pmids":["34980194"],"confidence":"High","gaps":["Endogenous interaction not validated in native neurons","Trafficking step (ER exit, Golgi, recycling) affected by SCAMP2 not identified"]},{"year":2023,"claim":"Discovery that SCAMP2 interacts with hSVCT1 and positively regulates vitamin C uptake, and that SCAMP2 knockdown impairs hiPSC neuronal differentiation, expanded the functional scope of SCAMP2 to nutrient transport and developmental processes.","evidence":"Affinity proteomics, co-immunoprecipitation, 14C-ascorbic acid uptake, siRNA knockdown, hiPSC differentiation assay","pmids":["36632962"],"confidence":"Medium","gaps":["Causal link between SCAMP2-dependent vitamin C uptake and neuronal differentiation not established","Single-lab observation awaiting independent replication"]},{"year":null,"claim":"The mechanistic basis for SCAMP2's bidirectional regulation of cargo surface expression—increasing some cargoes (NHE5, hSVCT1) while decreasing others (SERT, DAT, NKCC2, Cav3.2)—and whether this reflects cargo-specific adaptor interactions or context-dependent fusion regulation remains an open question.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of full-length SCAMP2 exists","No in vivo animal model phenotype reported","Relationship between PIP2 sequestration and cargo-specific trafficking outcomes is undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2,9]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[5,10,11]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[5,11]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1,2,3,9]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[4,6,7,13]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[4,8]}],"complexes":[],"partners":["ARF6","PLD1","SNAP23","STX4","STX1A","SLC6A4","SLC6A3","SLC9A7"],"other_free_text":[]},"mechanistic_narrative":"SCAMP2 is a tetraspanning membrane protein of post-Golgi recycling vesicles that functions as a critical regulator of late-stage exocytotic membrane fusion and surface trafficking of diverse membrane transporters and channels. Its conserved cytoplasmic E peptide domain (between transmembrane spans 2 and 3) binds PI(4,5)P2 through electrostatic interactions and couples Arf6-stimulated phospholipase D1 activity to fusion pore formation and dilation during regulated exocytosis, as demonstrated by dominant-negative mutagenesis, siRNA knockdown, and biophysical studies in neuroendocrine cells [PMID:12124380, PMID:16030257, PMID:17713930, PMID:18171723]. SCAMP2 directly interacts with and controls the exocytotic insertion or surface retention of multiple membrane transporters and channels—including SERT, DAT, NHE5, NHE7, NKCC2, hSVCT1, and Cav3.2 T-type calcium channels—through its E peptide domain and, in the case of NHE5, through an Arf6-dependent recycling endosome pathway [PMID:16870614, PMID:19276089, PMID:21205824, PMID:34980194]. At the plasma membrane, SCAMP2 associates with SNARE proteins syntaxin 4, SNAP-23, syntaxin 1, and complexin, consistent with its role at fusion sites [PMID:12124380, PMID:12475951]."},"prefetch_data":{"uniprot":{"accession":"O15127","full_name":"Secretory carrier-associated membrane protein 2","aliases":[],"length_aa":329,"mass_kda":36.6,"function":"Functions in post-Golgi recycling pathways. Acts as a recycling carrier to the cell surface","subcellular_location":"Golgi apparatus, trans-Golgi network membrane; Recycling endosome membrane","url":"https://www.uniprot.org/uniprotkb/O15127/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SCAMP2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000140497","cell_line_id":"CID000080","localizations":[{"compartment":"golgi","grade":3},{"compartment":"vesicles","grade":3},{"compartment":"membrane","grade":1}],"interactors":[{"gene":"TFRC","stoichiometry":10.0},{"gene":"SCAMP3","stoichiometry":10.0},{"gene":"NSF","stoichiometry":10.0},{"gene":"SCAMP1","stoichiometry":10.0},{"gene":"RAB11FIP5","stoichiometry":10.0},{"gene":"PDCD6IP","stoichiometry":10.0},{"gene":"RAB21","stoichiometry":10.0},{"gene":"RAB5B","stoichiometry":10.0},{"gene":"RAB2A","stoichiometry":10.0},{"gene":"WDFY1","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID000080","total_profiled":1310},"omim":[{"mim_id":"606913","title":"SECRETORY CARRIER MEMBRANE PROTEIN 3; SCAMP3","url":"https://www.omim.org/entry/606913"},{"mim_id":"606912","title":"SECRETORY CARRIER MEMBRANE PROTEIN 2; SCAMP2","url":"https://www.omim.org/entry/606912"},{"mim_id":"606911","title":"SECRETORY CARRIER MEMBRANE PROTEIN 1; SCAMP1","url":"https://www.omim.org/entry/606911"},{"mim_id":"600761","title":"SODIUM CHANNEL, EPITHELIAL 1, GAMMA SUBUNIT; SCNN1G","url":"https://www.omim.org/entry/600761"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"},{"location":"Vesicles","reliability":"Supported"},{"location":"Mid piece","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SCAMP2"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O15127","domains":[{"cath_id":"1.20.120","chopping":"144-294","consensus_level":"high","plddt":94.3654,"start":144,"end":294}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O15127","model_url":"https://alphafold.ebi.ac.uk/files/AF-O15127-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O15127-F1-predicted_aligned_error_v6.png","plddt_mean":76.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SCAMP2","jax_strain_url":"https://www.jax.org/strain/search?query=SCAMP2"},"sequence":{"accession":"O15127","fasta_url":"https://rest.uniprot.org/uniprotkb/O15127.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O15127/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O15127"}},"corpus_meta":[{"pmid":"17723134","id":"PMC_17723134","title":"Proteomic analysis of platelet alpha-granules using mass spectrometry.","date":"2007","source":"Journal of thrombosis and haemostasis : JTH","url":"https://pubmed.ncbi.nlm.nih.gov/17723134","citation_count":227,"is_preprint":false},{"pmid":"19376937","id":"PMC_19376937","title":"A mobile secretory vesicle cluster involved in mass transport from the Golgi to the plant cell exterior.","date":"2009","source":"The Plant cell","url":"https://pubmed.ncbi.nlm.nih.gov/19376937","citation_count":150,"is_preprint":false},{"pmid":"29180230","id":"PMC_29180230","title":"Glucocorticoids, genes and brain function.","date":"2017","source":"Progress in neuro-psychopharmacology & biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/29180230","citation_count":105,"is_preprint":false},{"pmid":"12670959","id":"PMC_12670959","title":"Binding of peptides with basic and aromatic residues to bilayer membranes: phenylalanine in the myristoylated alanine-rich C kinase substrate effector domain penetrates into the hydrophobic core of the bilayer.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12670959","citation_count":97,"is_preprint":false},{"pmid":"16870614","id":"PMC_16870614","title":"Subcellular redistribution of the serotonin transporter by secretory carrier membrane protein 2.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16870614","citation_count":69,"is_preprint":false},{"pmid":"22628180","id":"PMC_22628180","title":"Genome-wide association uncovers shared genetic effects among personality traits and mood states.","date":"2012","source":"American journal of medical genetics. 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SCAMP2 co-immunoprecipitates with SNARE proteins SNAP-23 and syntaxin 4 at the plasma membrane.\",\n      \"method\": \"Permeabilized cell exocytosis assay, peptide inhibition, co-immunoprecipitation, immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (permeabilized cell assay, CoIP, peptide structure-activity), replicated in two cell types\",\n      \"pmids\": [\"12124380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SCAMP2 localizes to plasma membranes at putative docking/fusion sites with syntaxin1 and complexin in PC12 cells. Overexpression of SCAMP2 point mutants in the E peptide (but not wild-type SCAMP2) dose-dependently inhibits depolarization-induced and calcium-stimulated secretion; this inhibition is largely rescued by lysophosphatidylcholine, implicating SCAMP2 E peptide in fusion pore formation during granule exocytosis.\",\n      \"method\": \"Regulated overexpression of point mutants, amperometry, pharmacological rescue with lysophosphatidylcholine, confocal colocalization\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — dominant-negative mutagenesis with pharmacological rescue and functional readout\",\n      \"pmids\": [\"12475951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SCAMP2 interacts with Arf6 and phospholipase D1 (PLD1) in PC12 cells; co-immunoprecipitation is enhanced after cell depolarization and GTPγS treatment. A SCAMP2-derived E peptide suppresses PLD activity. A SCAMP2 point mutant with decreased Arf6 association inhibits early membrane fusion events and fusion pore dilation, while mutant Arf6 deficient in PLD1 activation only inhibits early fusion events, placing SCAMP2 downstream of Arf6-PLD1 in exocytosis and specifically linking it to fusion pore formation.\",\n      \"method\": \"Co-immunoprecipitation, amperometry, dominant-negative mutants, peptide inhibition of PLD activity\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal CoIP, epistasis via double mutant analysis, functional amperometry readout\",\n      \"pmids\": [\"16030257\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"SCAMP2 E peptide binds and sequesters PI(4,5)P2 within membranes through an electrostatic mechanism. EPR analysis shows R4 (R204 in full-length SCAMP2) is critical for PIP2 binding. Corresponding SCAMP2 point mutants (SC2-R204A, SC2-W202A) inhibit dense core vesicle exocytosis in PC12 cells, specifically decreasing fusion pore opening probability and stability of initially opened pores, establishing that SCAMP2-PIP2 interaction regulates fusion pore formation.\",\n      \"method\": \"EPR spectroscopy, NMR, alanine-scanning mutagenesis of full-length SCAMP2, amperometry in PC12 cells\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro biophysical assay (EPR, NMR) combined with mutagenesis and functional cell-based assay\",\n      \"pmids\": [\"17713930\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"SCAMP2 interacts with the serotonin transporter (SERT) via yeast two-hybrid, GST pulldown, and co-immunoprecipitation from rat brain homogenate. Co-expression of SCAMP2 with SERT decreases cell-surface SERT and 5-HT uptake. SCAMP2 co-localizes with SERT in lipid raft/syntaxin 1A-containing structures. A single point mutation C201A in the SCAMP2 E peptide abolishes SCAMP2-mediated SERT downregulation without disrupting physical interaction, indicating the E peptide domain mediates the functional effect on trafficking.\",\n      \"method\": \"Yeast two-hybrid, GST pulldown, co-immunoprecipitation from brain homogenate, confocal microscopy, radioligand uptake assay, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including native brain tissue CoIP and mutagenesis dissecting physical vs. functional interaction\",\n      \"pmids\": [\"16870614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SCAMP2 interacts with the C-terminus of NHE7 (organellar Na+/K+/H+ exchanger) identified by yeast two-hybrid; interaction confirmed by co-immunolocalization, co-immunoprecipitation, co-sedimentation in sucrose gradients, and in vitro binding. SCAMP2 binds NHE7 through a cytoplasmic TM2-TM3 loop (residues 184-208). Deletion of this loop or overexpression of the TM2-TM3 construct redistributes NHE7 from TGN to scattered recycling vesicles, indicating SCAMP2 participates in shuttling NHE7 between recycling vesicles and TGN.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, co-sedimentation, in vitro binding assay, deletion mutagenesis, confocal microscopy\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, domain mapping with deletion mutants and functional redistribution phenotype\",\n      \"pmids\": [\"15840657\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SCAMP2 binds directly to both the N- and C-terminal cytosolic extensions of the brain-enriched Na+/H+ exchanger NHE5, as shown by in vitro protein-protein interaction assays and co-immunoprecipitation. Co-expression of SCAMP2 (but not SCAMP5) increases NHE5 cell-surface abundance and transport activity. SCAMP2-specific N-terminal cytosolic domain is required for this effect. SCAMP2-mediated NHE5 surface targeting is reversed by dominant-negative Arf6 but not dominant-negative Rab11, placing SCAMP2 in an Arf6-dependent recycling endosome pathway.\",\n      \"method\": \"In vitro protein-protein interaction assay, co-immunoprecipitation, surface biotinylation, dominant-negative GTPase epistasis, confocal microscopy\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vitro direct binding, surface assay, and GTPase epistasis defining pathway position\",\n      \"pmids\": [\"19276089\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SCAMP2 interacts with the renal NKCC2 co-transporter identified by yeast two-hybrid and confirmed by co-immunoprecipitation and confocal co-localization. SCAMP2 overexpression decreases NKCC2 cell-surface abundance and transport activity by reducing exocytotic insertion (not endocytic retrieval), as shown by sodium 2-mercaptoethane sulfonate cleavage assay. The C201A E peptide mutation of SCAMP2 abolishes this regulation, indicating the E peptide domain mediates the effect on exocytotic trafficking.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, confocal microscopy, surface biotinylation, MesNa cleavage assay, site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods distinguishing exo- from endocytic mechanisms with mutagenesis\",\n      \"pmids\": [\"21205824\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SCAMP2 interacts with and regulates the dopamine transporter (DAT). DAT-SCAMP2 interaction is confirmed by co-immunoprecipitation and FRET microscopy. Co-expression of SCAMP2 with DAT reduces dopamine uptake and cell-surface DAT levels, mirroring its previously described effect on SERT.\",\n      \"method\": \"Co-immunoprecipitation, FRET microscopy, dopamine uptake assay, surface expression measurement\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — reciprocal CoIP and FRET, single lab, replicates prior SERT finding\",\n      \"pmids\": [\"21295544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"RNA interference-mediated knockdown of SCAMP2 in PC12 cells decreases the number and frequency of depolarization-induced dense core vesicle exocytotic events and delays the onset of exocytosis, as measured by amperometry. SCAMP2 knockdown also increases rapid fusion pore closure and decreases pore dilation without affecting upstream DCV distribution or calcium signaling, placing SCAMP2 specifically at the final membrane fusion step.\",\n      \"method\": \"siRNA knockdown, amperometry, calcium imaging\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function with high-resolution functional readout (amperometry) distinguishing fusion pore dynamics from upstream events\",\n      \"pmids\": [\"18171723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"SCAMP1 and SCAMP2 extensively co-localize in post-Golgi recycling carrier membranes and can be co-immunoprecipitated, indicating they form protein complexes that may include homomultimers. Cross-linking studies suggest SCAMP1 forms homomultimers in situ.\",\n      \"method\": \"Co-immunoprecipitation, chemical cross-linking, immunocytochemistry, velocity centrifugation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single-lab co-immunoprecipitation and crosslinking without functional consequence\",\n      \"pmids\": [\"9224770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Three mammalian SCAMPs (1, 2, 3) are products of distinct genes with highly conserved sequences and extensively co-localize in post-Golgi recycling vesicles as shown by double-label immunofluorescence, suggesting shared function at the same vesicular transport sites rather than separate pathways.\",\n      \"method\": \"cDNA cloning, immunofluorescence double labeling, subcellular fractionation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — localization study with limited functional link\",\n      \"pmids\": [\"9378760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"SCAMP1 and SCAMP3, but not SCAMP2, are tyrosine phosphorylated in EGF-stimulated murine fibroblasts overexpressing EGFR. SCAMP3 phosphorylation is stimulated by EGFR in vitro, and EGF induces SCAMP-EGFR co-immunoprecipitation, suggesting phosphorylation is linked to EGFR internalization/downregulation. SCAMP2 is specifically excluded from this phosphorylation.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation, phosphatase treatment, vanadate inhibition\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro kinase assay and CoIP, but SCAMP2-specific finding is a negative result (not phosphorylated)\",\n      \"pmids\": [\"9658162\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SCAMP2 was identified as a novel Cav3.2 T-type calcium channel interacting protein. Co-expression of SCAMP2 with Cav3.2 in mammalian cells nearly abolishes whole-cell T-type current by reducing channel surface expression (evidenced by loss of intramembrane charge movement without reduction in total protein). Single amino acid mutations in the SCAMP2 E peptide partly reverse this effect. The downregulation also applies to Cav3.1 and Cav3.3 isoforms.\",\n      \"method\": \"Co-expression, whole-cell patch clamp, intramembrane charge movement recording, site-directed mutagenesis of E peptide\",\n      \"journal\": \"Molecular brain\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — electrophysiology combined with charge movement analysis distinguishes trafficking from gating effects, plus mutagenesis\",\n      \"pmids\": [\"34980194\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SCAMP2 was identified as a novel interacting protein of the human sodium-dependent vitamin C transporter hSVCT1 by affinity pull-down proteomics and confirmed by co-immunoprecipitation. Co-expression of hSVCT1 and SCAMP2 leads to co-localization at intracellular structures and plasma membrane. Overexpression of SCAMP2 potentiates ascorbic acid uptake; knockdown of SCAMP2 decreases uptake. SCAMP2 knockdown also impairs hiPSC differentiation to neurons.\",\n      \"method\": \"Affinity tagging proteomics, co-immunoprecipitation, confocal microscopy, 14C-ascorbic acid uptake assay, siRNA knockdown, hiPSC neuronal differentiation\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — CoIP plus functional uptake assay and knockdown phenotype, single lab\",\n      \"pmids\": [\"36632962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"SCAMP2 protein was identified by immunoelectron microscopy in platelet alpha-granule membranes, establishing its subcellular localization to this secretory organelle.\",\n      \"method\": \"Immunoelectron microscopy, sucrose gradient fractionation, mass spectrometry\",\n      \"journal\": \"Journal of thrombosis and haemostasis : JTH\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by immunoelectron microscopy, no functional consequence established\",\n      \"pmids\": [\"17723134\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SCAMP2 is a tetraspanning post-Golgi vesicle membrane protein that functions primarily in the late steps of regulated exocytosis via its conserved cytoplasmic E peptide domain, which interacts with PI(4,5)P2 and couples Arf6-stimulated PLD1 activity to fusion pore formation and dilation; it also regulates the surface trafficking of diverse membrane transporters (SERT, DAT, NHE5, NHE7, NKCC2, hSVCT1, Cav3.2) by controlling their exocytotic insertion into or retention at the plasma membrane through recycling endosome pathways.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SCAMP2 is a tetraspanning membrane protein of post-Golgi recycling vesicles that functions as a critical regulator of late-stage exocytotic membrane fusion and surface trafficking of diverse membrane transporters and channels. Its conserved cytoplasmic E peptide domain (between transmembrane spans 2 and 3) binds PI(4,5)P2 through electrostatic interactions and couples Arf6-stimulated phospholipase D1 activity to fusion pore formation and dilation during regulated exocytosis, as demonstrated by dominant-negative mutagenesis, siRNA knockdown, and biophysical studies in neuroendocrine cells [PMID:12124380, PMID:16030257, PMID:17713930, PMID:18171723]. SCAMP2 directly interacts with and controls the exocytotic insertion or surface retention of multiple membrane transporters and channels—including SERT, DAT, NHE5, NHE7, NKCC2, hSVCT1, and Cav3.2 T-type calcium channels—through its E peptide domain and, in the case of NHE5, through an Arf6-dependent recycling endosome pathway [PMID:16870614, PMID:19276089, PMID:21205824, PMID:34980194]. At the plasma membrane, SCAMP2 associates with SNARE proteins syntaxin 4, SNAP-23, syntaxin 1, and complexin, consistent with its role at fusion sites [PMID:12124380, PMID:12475951].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Establishing SCAMP2 as a distinct gene product co-localizing with SCAMP1 and SCAMP3 in post-Golgi recycling vesicles provided the initial framework that SCAMPs function at shared vesicular transport sites and can form protein complexes.\",\n      \"evidence\": \"cDNA cloning, double-label immunofluorescence, co-immunoprecipitation, and chemical cross-linking in mammalian cells\",\n      \"pmids\": [\"9224770\", \"9378760\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional consequence of SCAMP1-SCAMP2 interaction was demonstrated\", \"Stoichiometry and composition of SCAMP complexes undefined\", \"Role in vesicle trafficking inferred from localization only\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrating that the SCAMP2 E peptide inhibits exocytosis at a step beyond Ca2+/ATP-dependent priming and that E peptide point mutants block secretion (rescuable by lysophosphatidylcholine) established SCAMP2 as a direct participant in fusion pore formation rather than upstream vesicle priming.\",\n      \"evidence\": \"Synthetic peptide inhibition in permeabilized mast cells, dominant-negative overexpression in PC12 cells with amperometry, pharmacological rescue, co-immunoprecipitation with SNAP-23/syntaxin 4\",\n      \"pmids\": [\"12124380\", \"12475951\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which lysophosphatidylcholine bypasses SCAMP2 not fully resolved\", \"Structural basis for E peptide–SNARE association unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identification of SCAMP2 interaction with Arf6 and PLD1, and epistasis experiments showing SCAMP2 acts downstream of Arf6-PLD1 specifically at the fusion pore dilation step, positioned SCAMP2 within a defined signaling pathway controlling the final membrane merger event.\",\n      \"evidence\": \"Co-immunoprecipitation enhanced by depolarization/GTPγS, amperometry with SCAMP2 and Arf6 mutants, peptide-based PLD inhibition in PC12 cells\",\n      \"pmids\": [\"16030257\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical contact between SCAMP2 and PLD1 not shown with purified proteins\", \"Whether PLD1-generated phosphatidic acid acts on SCAMP2 or independently on the pore is unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Discovery that SCAMP2 binds NHE7 through the TM2–TM3 cytoplasmic loop and controls NHE7 recycling between TGN and recycling vesicles extended SCAMP2 function beyond exocytosis to regulation of organellar transporter trafficking.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, in vitro binding, deletion mutagenesis with redistribution phenotype by confocal microscopy\",\n      \"pmids\": [\"15840657\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Directionality of SCAMP2 effect (anterograde vs. retrograde sorting of NHE7) not fully dissected\", \"Physiological consequence of NHE7 mislocalization unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Showing that SCAMP2 binds SERT and reduces its surface expression through the E peptide domain—dissociating physical binding from functional regulation via the C201A mutation—established SCAMP2 as a trafficking regulator of neurotransmitter transporters.\",\n      \"evidence\": \"Yeast two-hybrid, GST pulldown, co-immunoprecipitation from rat brain, radioligand uptake, site-directed mutagenesis\",\n      \"pmids\": [\"16870614\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SCAMP2 regulates SERT via exocytosis, endocytosis, or surface retention was not resolved\", \"In vivo relevance of SCAMP2–SERT interaction in brain not tested\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Biophysical demonstration that the E peptide binds and sequesters PI(4,5)P2 through R204, and that corresponding full-length SCAMP2 mutations impair fusion pore opening probability and stability, provided the first molecular mechanism for how SCAMP2 regulates membrane fusion—through local PIP2 sequestration.\",\n      \"evidence\": \"EPR spectroscopy and NMR on E peptide–lipid interactions, alanine-scanning mutagenesis with amperometry in PC12 cells\",\n      \"pmids\": [\"17713930\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PIP2 sequestration and PLD1 coupling are mechanistically linked or parallel remains undefined\", \"No structural model of E peptide within the bilayer at atomic resolution\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Loss-of-function knockdown confirming that endogenous SCAMP2 is required for normal exocytotic event frequency, onset kinetics, and fusion pore dilation validated the gain-of-function mutant studies and established SCAMP2 as a necessary component of the exocytotic machinery.\",\n      \"evidence\": \"siRNA knockdown in PC12 cells with amperometry and calcium imaging\",\n      \"pmids\": [\"18171723\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Redundancy with other SCAMPs not evaluated by double knockdown\", \"Effect on kiss-and-run versus full fusion not quantitatively separated\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrating that SCAMP2 increases NHE5 surface expression through an Arf6-dependent (but Rab11-independent) recycling endosome pathway linked SCAMP2's transporter trafficking function to the same Arf6 axis involved in its exocytotic role.\",\n      \"evidence\": \"In vitro binding, co-immunoprecipitation, surface biotinylation, dominant-negative GTPase epistasis in heterologous cells\",\n      \"pmids\": [\"19276089\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether SCAMP2 acts as a cargo adaptor or a general fusion regulator in recycling endosomes is unresolved\", \"Native neuronal validation lacking\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extension of SCAMP2's transporter regulatory repertoire to NKCC2 (reducing exocytotic insertion) and DAT (reducing surface levels) demonstrated the generality of E peptide–dependent surface trafficking control across functionally diverse cargo proteins.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, MesNa cleavage assay distinguishing exo- from endocytosis for NKCC2; CoIP and FRET for DAT\",\n      \"pmids\": [\"21205824\", \"21295544\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why SCAMP2 increases surface expression of some cargoes (NHE5, hSVCT1) but decreases others (SERT, DAT, NKCC2, Cav3.2) is mechanistically unexplained\", \"Cargo selectivity determinants not mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identification of SCAMP2 as a regulator of Cav3.2 T-type calcium channel surface expression—nearly abolishing current by blocking forward trafficking without reducing total protein—extended SCAMP2's E peptide–dependent trafficking control to ion channels.\",\n      \"evidence\": \"Whole-cell patch clamp, intramembrane charge movement recording, E peptide mutagenesis in heterologous expression system\",\n      \"pmids\": [\"34980194\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous interaction not validated in native neurons\", \"Trafficking step (ER exit, Golgi, recycling) affected by SCAMP2 not identified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Discovery that SCAMP2 interacts with hSVCT1 and positively regulates vitamin C uptake, and that SCAMP2 knockdown impairs hiPSC neuronal differentiation, expanded the functional scope of SCAMP2 to nutrient transport and developmental processes.\",\n      \"evidence\": \"Affinity proteomics, co-immunoprecipitation, 14C-ascorbic acid uptake, siRNA knockdown, hiPSC differentiation assay\",\n      \"pmids\": [\"36632962\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal link between SCAMP2-dependent vitamin C uptake and neuronal differentiation not established\", \"Single-lab observation awaiting independent replication\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The mechanistic basis for SCAMP2's bidirectional regulation of cargo surface expression—increasing some cargoes (NHE5, hSVCT1) while decreasing others (SERT, DAT, NKCC2, Cav3.2)—and whether this reflects cargo-specific adaptor interactions or context-dependent fusion regulation remains an open question.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of full-length SCAMP2 exists\", \"No in vivo animal model phenotype reported\", \"Relationship between PIP2 sequestration and cargo-specific trafficking outcomes is undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [5, 10, 11]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [5, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1, 2, 3, 9]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [4, 6, 7, 13]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [4, 8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"ARF6\", \"PLD1\", \"SNAP23\", \"STX4\", \"STX1A\", \"SLC6A4\", \"SLC6A3\", \"SLC9A7\"],\n    \"other_free_text\": []\n  }\n}\n```"}