{"gene":"SLC3A2","run_date":"2026-06-10T07:46:34","timeline":{"discoveries":[{"year":1998,"finding":"SLC3A2 (4F2hc/CD98hc) heavy chain is required for functional surface expression of the LAT1 light chain; co-expression in Xenopus oocytes reconstitutes Na+-independent system L amino acid transport of large neutral amino acids with branched or aromatic side chains.","method":"Expression cloning and functional reconstitution in Xenopus oocytes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct reconstitution in Xenopus oocytes, replicated across multiple independent labs (PMIDs 9726963, 9751058, 9915839)","pmids":["9726963","9751058","9915839"],"is_preprint":false},{"year":1998,"finding":"4F2hc (SLC3A2) cysteine 109 (Cys-109) forms a disulfide bond that covalently links the heavy chain to its light chain subunits; mutation C109S abolishes heterodimer formation and drastically reduces co-expressed amino acid transport activity.","method":"Site-directed mutagenesis, co-immunoprecipitation, transport assay in Xenopus oocytes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis with functional transport readout, replicated in multiple studies (PMIDs 9829974, 10897033, 9761775)","pmids":["9829974","10897033","9761775"],"is_preprint":false},{"year":1998,"finding":"4F2hc (SLC3A2) associates with y+LAT-1 to form a heterodimer mediating system y+L amino acid transport (cationic and neutral amino acids exchanged with sodium); this is the molecular basis of the y+L transport system.","method":"Functional co-expression in Xenopus oocytes, co-immunoprecipitation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — functional reconstitution, independently replicated (PMIDs 9829974, 10903140)","pmids":["9829974","10903140"],"is_preprint":false},{"year":1999,"finding":"SLC3A2 (4F2hc) controls intracellular trafficking and plasma membrane localization of its light chain partners: 4F2hc reaches the plasma membrane alone, but the light chain (LAT1) requires 4F2hc for surface expression. In cells expressing cadherins, 4F2hc is selectively localized to cell-cell adhesion sites.","method":"Mammalian cell transfection, immunofluorescence, flow cytometry","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (transfection, immunofluorescence, cell fractionation), replicated across labs","pmids":["9915839"],"is_preprint":false},{"year":1999,"finding":"LAT-2 co-expressed with 4F2hc (SLC3A2) mediates Na+-independent, broad-specificity system L transport of small and large zwitterionic amino acids via an exchanger mechanism; LAT-2 alone has intracellular location and no transport activity.","method":"Functional co-expression in Xenopus oocytes, tagged protein localization","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution with localization and transport data, replicated (PMID 10391915, 11311135)","pmids":["10391915"],"is_preprint":false},{"year":2000,"finding":"The 4F2hc/y+LAT2 heterodimer mediates arginine efflux in exchange for extracellular glutamine and leucine (antiport mechanism); arginine has the highest affinity for the intracellular binding site, making arginine release the main physiological function.","method":"Functional reconstitution in Xenopus oocytes, radiolabeled amino acid transport assays","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — detailed in vitro transport characterization with substrate competition in oocytes, single lab","pmids":["10903140"],"is_preprint":false},{"year":2000,"finding":"The cytoplasmic and transmembrane domains of CD98hc (SLC3A2) are required for its effects on integrin function, while the extracellular domain is required for stimulation of amino acid (isoleucine) transport; these two functions are separable and require distinct domains.","method":"CD98hc/CD69 chimera construction, isoleucine transport assays, integrin signaling readouts in mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — domain dissection via chimeras with both functional transport and signaling readouts, single lab","pmids":["11121428"],"is_preprint":false},{"year":2000,"finding":"The 4F2hc/LAT1 heterodimeric complex mediates Na+-independent L-DOPA transport across the blood-brain barrier; LAT1 is predominantly expressed in brain microvessels and forms a heterodimer with 4F2hc in brain capillary endothelial cells.","method":"Northern hybridization, immunoblotting, radiolabeled L-DOPA uptake assay, immunohistochemistry","journal":"Brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple methods (protein expression, functional uptake assay, localization), single lab","pmids":["11011012"],"is_preprint":false},{"year":2001,"finding":"The extracellular domain of 4F2hc (SLC3A2) is specifically required for surface expression of LAT2 and y+LAT2 but not LAT1; truncated 4F2hc containing only the cytosolic N-terminus and transmembrane helix retains partial ability to promote LAT1 surface expression.","method":"C-terminal truncation mutants of 4F2hc co-expressed with light chains in Xenopus oocytes and mammalian cells","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — systematic deletion mutagenesis with functional surface-expression readout, multiple light chains tested","pmids":["11311135"],"is_preprint":false},{"year":2004,"finding":"CD98hc (SLC3A2) physically associates with β1 integrins and is required for integrin-dependent cell spreading, migration, and protection from apoptosis; loss of CD98hc impairs adhesion-induced Akt and Rac GTPase activation. A CD98hc mutant that interacts with β1 integrins but not light chains restores integrin signaling, showing amino acid transport is dispensable for these functions.","method":"Gene knockout (CD98hc-null cells), rescue with domain mutants, cell spreading/migration assays, Akt/Rac activation assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with domain-specific rescue, multiple orthogonal functional readouts, single lab","pmids":["15625115"],"is_preprint":false},{"year":2004,"finding":"CD98hc (SLC3A2) interaction with β1 integrins requires its transmembrane domain (amino acids 82-87); this association drives FAK-dependent PI3K activation and cellular transformation (anchorage-independent growth).","method":"CD98hc/CD69 chimeras, co-immunoprecipitation, PI3K activation assays, soft-agar colony formation, xenograft tumor assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — domain mapping with chimeras, functional transformation assay and signaling, replicated findings","pmids":["15485886"],"is_preprint":false},{"year":2007,"finding":"Crystal structure of the 4F2hc (SLC3A2) ectodomain reveals a (βα)8 barrel and antiparallel β sandwich related to bacterial α-glycosidases but lacking catalytic residues; Cys109 is located near the transmembrane domain and participates in a disulfide-linked homodimer at the cell surface.","method":"X-ray crystallography (2.1 Å and 2.8 Å crystal forms), cross-linking experiments, cell surface homodimerization assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution crystal structure with biochemical validation of homodimerization and Cys109 positioning","pmids":["17724034"],"is_preprint":false},{"year":2007,"finding":"CD98hc (SLC3A2) interacts with integrin β cytoplasmic domain via the C-terminal 8 residues of β3 (Thr755–Thr762); point mutations T755K or T758M in β3 abolish CD98hc association and impair integrin-mediated cell spreading.","method":"Homology scanning mutagenesis, co-immunoprecipitation, cell spreading assays with Drosophila βPS gain-of-function mutations","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal gain/loss-of-function mutagenesis on both interacting proteins with functional cellular readouts","pmids":["17597067"],"is_preprint":false},{"year":2007,"finding":"CD98hc (SLC3A2) participates in fibronectin matrix assembly by enabling RhoA GTPase activation downstream of integrins; CD98hc is not required for Fn biosynthesis or integrin repertoire/affinity but is required for force generation on the matrix.","method":"CD98hc knockout cells, fibronectin matrix assembly assay, RhoA activity assay, in vitro and in vivo matrix assembly","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with specific mechanistic rescue, multiple functional readouts including RhoA activation","pmids":["17682053"],"is_preprint":false},{"year":2009,"finding":"B cell-specific deletion of CD98hc (SLC3A2) abolishes B cell proliferation and plasma cell formation; the integrin-binding domain of CD98hc (not the amino acid transport function) is required for B cell proliferation, acting via Erk1/2 activation and p27 downregulation.","method":"B cell-specific conditional knockout, domain-specific rescue mutants, Erk1/2 activation assays, FACS cell cycle analysis","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with domain-specific functional rescue, signaling readouts, multiple methods","pmids":["19270713"],"is_preprint":false},{"year":2011,"finding":"4F2hc (SLC3A2) stabilizes GLUT1 protein at the plasma membrane and increases glucose uptake; 4F2hc and GLUT1 physically associate (co-immunoprecipitation confirmed endogenously in mouse brain and HeLa cells), and 4F2hc overexpression or knockdown respectively increases or decreases GLUT1 protein stability without affecting GLUT1 mRNA.","method":"Split-ubiquitin membrane yeast two-hybrid, co-immunoprecipitation, cycloheximide chase, radiolabeled glucose uptake assay, siRNA knockdown","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP confirmed endogenously, protein stability chase, functional glucose uptake assay, single lab","pmids":["21270293"],"is_preprint":false},{"year":2013,"finding":"4F2hc (SLC3A2) silencing in HeLa cells impairs FAK/Akt/ERK1/2 integrin signaling, reduces MMP-2 expression/activity, and allows galectin-3 accumulation that cannot signal due to impaired 4F2hc interaction; loss of 4F2hc disrupts 4F2hc/β1-integrin/CD147 heterocomplexes, leading to β-catenin proteasomal degradation.","method":"Stable miRNA-mediated silencing, co-immunoprecipitation, FAK/Akt/ERK phosphorylation assays, MMP-2 activity assay, xenograft tumor model","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — stable KD with multiple downstream signaling readouts, single lab","pmids":["23651923"],"is_preprint":false},{"year":2014,"finding":"4F2hc (SLC3A2) extracellular domain covers the extracellular face of the LAT2 light chain and stabilizes it in detergent-solubilized membranes; the 4F2hc ectodomain alone is sufficient to stabilize LAT2 and allows functional reconstitution in proteoliposomes.","method":"Transmission electron microscopy single-particle analysis, docking, crosslinking, proteoliposome reconstitution, stability assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Moderate — EM structural analysis combined with biochemical stabilization and functional reconstitution, single lab","pmids":["24516142"],"is_preprint":false},{"year":2014,"finding":"CD98hc (SLC3A2) loss protects against Ras-driven skin carcinogenesis; CD98hc mediates stiffness sensing by increasing Rho kinase (ROCK) activity and YAP/TAZ-mediated transcription in response to matrix rigidity, amplifying a positive feedback loop that increases ECM stiffness.","method":"Conditional KO mouse model, chemical carcinogenesis, tumor regression after inducible deletion, RhoA/ROCK activity assays, YAP/TAZ reporter","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic model with mechanistic signaling readouts (ROCK/YAP/TAZ), both prevention and regression demonstrated","pmids":["25267066"],"is_preprint":false},{"year":2015,"finding":"The lysosomal protein LAPTM4b binds LAT1-4F2hc (SLC7A5-SLC3A2) and recruits this complex to lysosomes, enabling leucine uptake into lysosomes and mTORC1 activation via V-ATPase stimulation.","method":"Co-immunoprecipitation, lysosomal fractionation, leucine uptake assays, mTORC1 activation (S6K phosphorylation), LAPTM4b knockdown","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal pulldown, subcellular fractionation, functional mTORC1 signaling assay, single lab","pmids":["25998567"],"is_preprint":false},{"year":2015,"finding":"CD98hc-associated transporters (xCT, LAT1, y+LAT2) control reactive oxygen species and intracellular amino acid levels; CD98hc deletion causes ferroptosis due to inability to compensate CD98hc/xCT loss. CD98hc amino acid transport (not integrin signaling) is required for in vitro cell proliferation.","method":"CD98hc chimeric mutant rescue experiments, ROS measurement, GSH assay, β-mercaptoethanol rescue, ferroptosis inhibitor rescue","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — domain uncoupling with functional chimeras, multiple metabolic readouts, ferroptosis rescue experiments","pmids":["26945935"],"is_preprint":false},{"year":2016,"finding":"Slc3a2 is required for maintenance of Foxp3+ regulatory T cells in vivo; Slc3a2-deficient Treg cells show impaired isoleucine-induced mTORC1 activation and altered metabolic state, and Slc3a2-specific Treg KO mice develop multi-organ inflammation.","method":"Treg-specific conditional knockout, in vivo proliferation assays, mTORC1 activation (S6K/4EBP1), metabolic profiling, BCAA-reduced diet experiments","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic KO with mechanistic mTORC1 signaling and metabolic readouts, in vivo phenotype","pmids":["29141216"],"is_preprint":false},{"year":2017,"finding":"LAT1 stabilizes 4F2hc (SLC3A2) protein via a chaperone-like function in trophoblastic cells; LAT1 knockout drastically reduces 4F2hc protein (but not mRNA) and prevents syncytiotrophoblast formation, because 4F2hc has fusogenic activity required for trophoblast cell fusion.","method":"LAT1 knockout mice, trophoblast LAT1 knockdown (BeWo cells), western blot for 4F2hc, forskolin-induced cell fusion assay","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with in vitro knockdown corroboration, protein stability and cell fusion functional readouts","pmids":["28320871"],"is_preprint":false},{"year":2018,"finding":"CD98hc (SLC3A2) regulates integrin mechanosensing via sphingolipid biosynthesis: loss of CD98hc decreases sphingolipid availability, preventing membrane recruitment and activation of Src kinases and GEF-H1, and impairing RhoA activation in response to matrix rigidity.","method":"Conditional KO in dermal cells, sphingolipid profiling (lipidomics), DES2 expression analysis, RhoA/Src/GEF-H1 activity assays, rescue with sphingolipid supplementation","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with lipidomic profiling and targeted mechanistic rescue, in vivo and in vitro readouts","pmids":["30451822"],"is_preprint":false},{"year":2019,"finding":"Cryo-EM structure of human LAT1-4F2hc (SLC7A5-SLC3A2) heterodimer at 3.3 Å resolution reveals that besides the disulfide bond, LAT1 interacts extensively with 4F2hc on the extracellular side, within the membrane, and on the intracellular side; 4F2hc is essential for transport activity of the complex; LAT1 is in inward-open conformation.","method":"Cryo-electron microscopy (3.3 Å and 3.5 Å), inhibitor-bound structure, biochemical transport activity assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — near-atomic resolution cryo-EM structure with biochemical validation, independent replication (PMID 33758168)","pmids":["30867591"],"is_preprint":false},{"year":2019,"finding":"CD98hc (SLC3A2) deficiency causes replicative stress by reducing BCAA/aromatic amino acid availability, which diminishes glucose uptake/glycolysis, pentose phosphate pathway activity, and nucleotide pool; nucleoside supplementation rescues S-phase delay and proliferation defects.","method":"CD98hc KO cells, metabolomics, nucleotide pool measurement, DNA damage response (γH2AX), S-phase analysis by BrdU, nucleoside rescue","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KO with metabolomics and mechanistic nucleoside rescue, multiple orthogonal assays","pmids":["31575908"],"is_preprint":false},{"year":2019,"finding":"PTPRJ receptor tyrosine phosphatase physically interacts with CD98hc (SLC3A2) and promotes its proteasomal degradation; PTPRJ overexpression reduces CD98hc protein levels, and proteasome inhibitor MG132 reverses this.","method":"Proteomic pulldown, co-immunoprecipitation, proteasome inhibitor rescue, PTPRJ overexpression in lung cancer cells","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus pharmacological rescue, single lab","pmids":["29805737"],"is_preprint":false},{"year":2020,"finding":"4F2hc modulates the substrate affinity and specificity of its light chains LAT1 and LAT2; light chains are functional transporters without 4F2hc in Pichia pastoris, but association with 4F2hc alters their kinetic properties.","method":"Heterologous expression in Pichia pastoris, radiolabeled amino acid transport assays comparing HAT complexes vs light chains alone","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — reconstituted transport assay in yeast expression system, novel functional observation, single lab","pmids":["33066406"],"is_preprint":false},{"year":2020,"finding":"CD98hc (SLC3A2) forms a molecular complex with β1 integrin and TRPV4 in focal adhesions; CD98hc knockdown inhibits TRPV4-mediated calcium influx induced by mechanical forces (but not by chemical activators); force must be transmitted from β1 integrin C-terminus via CD98hc cytoplasmic tail to the ankyrin repeat domain of TRPV4 for ultra-rapid mechanotransduction.","method":"Co-immunoprecipitation, co-localization imaging, CD98hc siRNA knockdown, calcium imaging with force application vs. chemical TRPV4 activation","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, knockdown with mechano-specific functional readout, single lab","pmids":["32989042"],"is_preprint":false},{"year":2021,"finding":"Cryo-EM structures of LAT1-4F2hc with potent inhibitors at 2.7–2.8 Å resolution reveal an outward-facing occluded conformation; inhibitors occupy the substrate binding pocket with tails wedged between the binding site and TM10 of LAT1, defining a distinct inhibition mechanism. A Diiodo-Tyr-bound structure reveals a possible intermediate between outward-occluded and outward-open states.","method":"Cryo-electron microscopy (2.7–3.4 Å), synthesis and IC50 measurement of inhibitors, transport assays","journal":"Cell discovery","confidence":"High","confidence_rationale":"Tier 1 / Moderate — near-atomic resolution cryo-EM with multiple inhibitor-bound states, functional transport data","pmids":["33758168"],"is_preprint":false},{"year":2021,"finding":"Plasmodium vivax merozoite surface protein PvRBP2a binds CD98hc (SLC3A2) on reticulocytes to mediate host cell invasion; CD98hc is expressed preferentially on immature reticulocytes (CD71+) and is a host receptor for P. vivax tropism.","method":"Mass spectrometry identification, flow cytometry, biochemical binding assays, parasite invasion inhibition assays","journal":"Nature microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (MS, flow cytometry, biochemical binding, invasion assay), single lab","pmids":["34294905"],"is_preprint":false},{"year":2022,"finding":"N-glycosylation of 4F2hc (SLC3A2) at Asn365, Asn381, Asn424, and Asn506 is required for its stability and trafficking to the plasma membrane; quadruple mutation of these sites severely impairs membrane trafficking and correlates with reduced LAT1 (SLC7A5) surface expression and transport activity.","method":"Site-directed mutagenesis of all four N-glycosylation sites, biotinylation surface assay, brefeldin A trafficking assay, LAT1 co-expression and transport assay","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — systematic mutagenesis of all four glycosylation sites with trafficking and functional transport readouts","pmids":["36028562"],"is_preprint":false},{"year":2022,"finding":"The polarity protein SCRIB binds SLC3A2 N-terminus and facilitates formation of a SCRIB/SLC3A2/LLGL2/SLC7A5 quaternary complex required for membrane localization of the leucine transporter; both SCRIB and SLC3A2 are required for cell proliferation and tamoxifen resistance in ER+ breast cancer.","method":"Co-immunoprecipitation, proximity ligation assay, siRNA knockdown of SCRIB and SLC3A2, membrane localization assay, cell proliferation assay","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with complex mapping and functional rescue, single lab","pmids":["35501367"],"is_preprint":false},{"year":2022,"finding":"Tumour-associated neutrophil-secreted AGR2 binds CD98hc (SLC3A2) as its functional receptor; AGR2 increases xCT transporter activity in a CD98hc-dependent manner, subsequently activating the RhoA/ROCK2 cascade to promote CRC cell migration.","method":"Co-immunoprecipitation, neutrophil-specific Agr2 KO mice, xCT activity assay, RhoA/ROCK2 phosphorylation, in vitro migration assay, in vivo liver metastasis model","journal":"Gut","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, in vivo KO model, functional xCT and signaling assays, single lab","pmids":["35086885"],"is_preprint":false},{"year":2023,"finding":"The glycosyltransferase B3GNT3 catalyzes N-glycosylation of 4F2hc (SLC3A2), stabilizes 4F2hc protein, and enhances interaction between 4F2hc and xCT; glycosylation-deficient 4F2hc fails to restore ferroptosis resistance and system Xc- activity in 4F2hc-deficient cells.","method":"N- and O-linked glycoproteomics, B3GNT3 KO, site-directed glycosylation mutants of 4F2hc, system Xc- activity (glutathione measurement), xenograft tumor model","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — glycoproteomic identification, KO and glycosylation mutagenesis with functional transport and ferroptosis readouts","pmids":["37479744"],"is_preprint":false},{"year":2023,"finding":"Skp2 E3 ligase controls SLC3A2 membrane localization and cystine/glutamate exchange function via K48-linked ubiquitination of SLC3A2; in sepsis, MEK/ERK pathway suppresses Skp2, reducing K48-ubiquitination of SLC3A2, impairing its membrane localization and triggering ferroptosis in pulmonary epithelial cells.","method":"Skp2 KO/overexpression, ubiquitination assay (K48 linkage), membrane fractionation, cystine uptake assay, lung injury model, Skp2 mRNA-LNP rescue","journal":"Cellular and molecular life sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ubiquitination assay with membrane localization and transport readout, in vivo model, single lab","pmids":["39079969"],"is_preprint":false},{"year":2023,"finding":"Neu5Ac (N-acetylneuraminic acid) promotes SLC3A2 binding to ubiquitin and p62-mediated degradation, leading to lipid peroxide accumulation and ferroptosis in vascular endothelial cells.","method":"Co-immunoprecipitation of SLC3A2 with ubiquitin/p62, ferroptosis markers (lipid peroxidation, GSH), ApoE-/- atherosclerosis mouse model, Fer-1 rescue","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP ubiquitination evidence with in vivo model and ferroptosis rescue, single lab","pmids":["37771765"],"is_preprint":false},{"year":2024,"finding":"FOXC1 transcription factor directly regulates endothelial Slc3a2 (and Slc7a5) expression; EC-specific Foxc1 deletion reduces SLC3A2/SLC7A5 expression, diminishes mTOR activity, and impairs retinal angiogenesis; mTOR agonist rescues the vascular growth defect.","method":"Endothelial-specific Foxc1 conditional KO, retinal angiogenesis assays, mTOR activity measurement, mTOR agonist rescue, OIR model","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with mechanistic mTOR signaling readout and pharmacological rescue, in vivo retinal model","pmids":["38755144"],"is_preprint":false},{"year":2018,"finding":"The SLC3A2-NRG1 fusion protein (transmembrane domain of SLC3A2 fused to EGF-like domain of NRG1) binds ERBB3/ERBB4, promotes ERBB2-ERBB3 heterocomplex formation and phosphorylation, and activates PI3K/AKT and MAPK pathways, driving lung cancer cell proliferation.","method":"Ligand-receptor binding assays, co-immunoprecipitation of ERBB2/ERBB3, phosphorylation assays, colony formation, xenograft tumor model, siRNA targeting","journal":"Molecular cancer therapeutics","confidence":"High","confidence_rationale":"Tier 2 / Strong — binding assays, co-IP, signaling assays, in vitro and in vivo functional readouts for fusion oncogene","pmids":["29959202"],"is_preprint":false},{"year":2018,"finding":"SLC3A2 functions upstream of mTOR1 in the unfolded protein response (UPR) in cardiomyocytes; SLC3A2 knockdown reduces activity of ATF4, ATF6, and XBP1 UPR sensors, and mTOR1 acts as mediator between SLC3A2 and UPR activation. SLC3A2 inhibition also enhances apoptosis.","method":"siRNA knockdown of SLC3A2 and mTOR1 in H9C2/PC12 cells, western blot for UPR markers, RNA sequencing, flow cytometry apoptosis assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA epistasis for UPR pathway, multiple downstream readouts, single lab","pmids":["30592731"],"is_preprint":false},{"year":2019,"finding":"Cryo-EM 3D-map (~13 Å) of human 4F2hc-LAT2 heterodimer places the 4F2hc ectodomain adjacent to the LAT2 transporter domain; the known 4F2hc ectodomain X-ray structure fits into the smaller density, revealing spatial relationship between subunits.","method":"Cryo-electron microscopy with Volta phase plate, single-particle analysis, fitting of X-ray ectodomain structure","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — structural EM map at limited resolution (~13 Å), single lab, no functional readout","pmids":["30795505"],"is_preprint":false},{"year":2015,"finding":"CD98 (SLC3A2/4F2hc) acts as a cell surface receptor for human β-defensin 3 (hBD3) internalization in epithelial cells; CD98 and hBD3 directly bind (mapped to CD98 residues 304-414 by surface plasmon resonance), and CD98 knockdown impairs hBD3 cell surface binding and internalization.","method":"FRET, surface plasmon resonance, co-localization, CD98 knockdown, internalization assay","journal":"Chemistry & biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay (SPR) and loss-of-function with internalization readout, single lab","pmids":["25641165"],"is_preprint":false},{"year":2000,"finding":"Transformation of BALB3T3 fibroblasts by CD98hc (SLC3A2) overexpression requires disulfide-linked association with CD98 light chain via Cys103 of the heavy chain; C103S mutation abolishes both light chain association and transformation activity, while C325S retains both.","method":"Stable transfection of wild-type and cysteine mutant CD98hc, immunoprecipitation for heterodimer detection, soft-agar colony formation, xenograft tumor assay","journal":"International journal of cancer","confidence":"High","confidence_rationale":"Tier 2 / Moderate — systematic Cys mutagenesis with co-IP and functional transformation assay, mechanistically informative","pmids":["10897033"],"is_preprint":false}],"current_model":"SLC3A2 (4F2hc/CD98hc) is a type II membrane glycoprotein that functions as the obligatory heavy chain subunit of heteromeric amino acid transporters (HATs): it covalently associates via a Cys109 disulfide bond with one of multiple light chain subunits (LAT1, LAT2, y+LAT1, y+LAT2, xCT, b0,+AT) to form distinct transport complexes with different substrate specificities, controls light chain trafficking to the plasma membrane, stabilizes light chains, and modulates their substrate affinity; structurally, its (βα)8 barrel ectodomain covers the extracellular face of the light chain and makes extensive contacts within and below the membrane as revealed by cryo-EM; independently of transport, SLC3A2 interacts via its transmembrane/cytoplasmic domains with β1 integrin cytoplasmic tails, mediating integrin-dependent Akt/Rac/RhoA/FAK signaling that drives cell spreading, proliferation, survival, mechanosensing, and matrix assembly; it also stabilizes GLUT1, acts upstream of mTORC1 and the UPR, and its N-glycosylation is required for protein stability and plasma membrane trafficking."},"narrative":{"mechanistic_narrative":"SLC3A2 (4F2hc/CD98hc) is a type II membrane glycoprotein that serves as the obligatory heavy-chain subunit of heteromeric amino acid transporters, pairing with multiple light chains to assemble transport systems of distinct substrate specificity, while independently coupling integrins to mechanosignaling [PMID:9726963, PMID:9751058, PMID:9915839, PMID:15625115]. It covalently links to its light-chain partners through a Cys109 disulfide bond, and loss of this cysteine abolishes heterodimer formation and transport [PMID:9829974, PMID:10897033, PMID:9761775]. Through this association SLC3A2 reconstitutes system L transport with LAT1 and LAT2 (large/small neutral amino acids), system y+L transport with y+LAT-1 and y+LAT2 (cationic/neutral amino acid antiport), and cystine/glutamate exchange with xCT [PMID:9726963, PMID:9751058, PMID:9915839, PMID:9829974, PMID:10903140, PMID:10391915, PMID:26945935]. SLC3A2 controls the intracellular trafficking, plasma-membrane delivery, and stability of its light chains and modulates their substrate affinity, while its own surface delivery and stability depend on N-glycosylation at Asn365/381/424/506 [PMID:9915839, PMID:11311135, PMID:33066406, PMID:36028562]. Structurally, its (βα)8-barrel ectodomain — related to bacterial α-glycosidases but catalytically dead — covers the extracellular face of the light chain and makes extensive contacts across the membrane and on the intracellular side, as resolved by crystallography and cryo-EM of the LAT1-4F2hc complex [PMID:17724034, PMID:24516142, PMID:30867591]. Independently of transport, SLC3A2 binds β1/β3 integrin cytoplasmic tails via its transmembrane/cytoplasmic domains and drives integrin-dependent Akt, Rac, RhoA, FAK and PI3K signaling that controls cell spreading, migration, survival, proliferation, fibronectin matrix assembly, and stiffness-dependent mechanosensing through ROCK and YAP/TAZ [PMID:11121428, PMID:15625115, PMID:15485886, PMID:17597067, PMID:17682053, PMID:25267066]. Its amino-acid transport function feeds anabolic and redox programs: leucine/isoleucine uptake activates mTORC1 (including at the lysosome via LAPTM4b) to sustain regulatory T-cell maintenance and angiogenesis, while xCT-mediated cystine import maintains glutathione and protects against ferroptosis [PMID:25998567, PMID:26945935, PMID:29141216, PMID:38755144]. SLC3A2 abundance is set post-translationally by ubiquitin ligases and glycosyltransferases (Skp2, B3GNT3, PTPRJ, p62) that gate its membrane localization and ferroptosis-relevant activity [PMID:29805737, PMID:37479744, PMID:39079969, PMID:37771765]. SLC3A2 additionally acts as a cell-surface receptor co-opted by Plasmodium vivax PvRBP2a and human β-defensin 3, and an SLC3A2-NRG1 transmembrane fusion drives ERBB-dependent oncogenic signaling [PMID:34294905, PMID:25641165, PMID:29959202].","teleology":[{"year":1998,"claim":"Established that SLC3A2 is the obligatory heavy chain enabling functional surface amino acid transport, defining its core role as a transporter assembly subunit rather than a transporter itself.","evidence":"Expression cloning and functional reconstitution of LAT1 with 4F2hc in Xenopus oocytes","pmids":["9726963","9751058","9915839"],"confidence":"High","gaps":["Did not resolve whether 4F2hc contributes transport residues or only chaperones the light chain","Substrate selectivity determinants not mapped"]},{"year":1998,"claim":"Identified the covalent basis of heavy/light chain pairing, showing a single disulfide bond is required for complex assembly and transport.","evidence":"C109S site-directed mutagenesis with co-IP and transport assays in oocytes","pmids":["9829974","10897033","9761775"],"confidence":"High","gaps":["Did not establish the order of folding/assembly relative to disulfide formation"]},{"year":1998,"claim":"Showed a single heavy chain pairs with multiple light chains to generate different transport systems, explaining how one gene supports diverse amino acid fluxes.","evidence":"Functional co-expression of 4F2hc with y+LAT-1 (and later LAT2, y+LAT2, xCT) in oocytes","pmids":["9829974","10903140"],"confidence":"High","gaps":["Tissue-level pairing preferences not defined","Did not address how a cell selects which light chain to assemble"]},{"year":2000,"claim":"Separated SLC3A2's transport and integrin functions onto distinct domains, revealing it as a bifunctional protein.","evidence":"CD98hc/CD69 chimeras with isoleucine transport and integrin signaling readouts; cysteine mutants in transformation assays","pmids":["11121428","10897033"],"confidence":"High","gaps":["Did not identify the direct integrin-tail contact residues at this stage","Downstream effectors of the integrin function unmapped here"]},{"year":2004,"claim":"Demonstrated genetically that the integrin-binding/signaling function, independent of amino acid transport, drives spreading, migration, and survival via Akt/Rac.","evidence":"CD98hc-null cells with transport-dead/integrin-competent rescue mutants and Akt/Rac assays; TM domain mapping and transformation assays","pmids":["15625115","15485886"],"confidence":"High","gaps":["Mechanism linking integrin tail engagement to GTPase activation not fully resolved","Did not address mechanotransduction directly"]},{"year":2007,"claim":"Defined the structural fold of the ectodomain and the reciprocal integrin-tail interaction interface, and tied SLC3A2 to RhoA-driven matrix assembly.","evidence":"X-ray crystallography of the ectodomain; β3 tail mutagenesis with co-IP; CD98hc-KO fibronectin matrix assembly and RhoA assays","pmids":["17724034","17597067","17682053"],"confidence":"High","gaps":["Ectodomain structure lacked the light chain and membrane context","How RhoA activation is mechanically coupled was unresolved"]},{"year":2009,"claim":"Showed the integrin-binding domain, not transport, is required for lymphocyte proliferation in vivo, generalizing the signaling function to immune development.","evidence":"B cell-specific conditional KO with domain rescue, Erk1/2 and p27 readouts","pmids":["19270713"],"confidence":"High","gaps":["Did not separate cell-intrinsic vs niche contributions fully","Receptor input upstream of Erk1/2 not defined"]},{"year":2011,"claim":"Extended SLC3A2's chaperone role beyond amino acid light chains by showing it stabilizes GLUT1 and boosts glucose uptake.","evidence":"Split-ubiquitin Y2H, endogenous reciprocal co-IP, cycloheximide chase, glucose uptake","pmids":["21270293"],"confidence":"High","gaps":["Structural basis of GLUT1 stabilization unknown","Whether the interaction is direct in the membrane not shown"]},{"year":2014,"claim":"Provided the membrane-context structure showing the ectodomain caps the light chain, and linked SLC3A2 to stiffness sensing via ROCK/YAP-TAZ in carcinogenesis.","evidence":"EM single-particle analysis and proteoliposome reconstitution of 4F2hc-LAT2; conditional KO carcinogenesis model with ROCK/YAP-TAZ readouts","pmids":["24516142","25267066"],"confidence":"High","gaps":["EM resolution insufficient for atomic contacts","Feedback loop quantification incomplete"]},{"year":2015,"claim":"Connected SLC3A2 transport activity to mTORC1 signaling and to redox homeostasis/ferroptosis protection, establishing two metabolic outputs.","evidence":"LAPTM4b co-IP, lysosomal fractionation and mTORC1 assays; CD98hc chimera rescue with ROS/GSH/ferroptosis readouts; β-defensin 3 SPR binding","pmids":["25998567","26945935","25641165"],"confidence":"High","gaps":["How lysosomal vs plasma-membrane pools are partitioned unclear","xCT-specific contribution vs other light chains not fully isolated"]},{"year":2018,"claim":"Resolved a lipid-based mechanism for SLC3A2 mechanosensing and identified a transmembrane fusion and UPR-coupling roles.","evidence":"Conditional KO with lipidomics and Src/GEF-H1/RhoA rescue; SLC3A2-NRG1 fusion binding/signaling assays; siRNA UPR epistasis in cardiomyocytes","pmids":["30451822","29959202","30592731"],"confidence":"High","gaps":["UPR coupling shown only by knockdown epistasis (Medium)","Direct lipid-binding by SLC3A2 not demonstrated"]},{"year":2019,"claim":"Delivered near-atomic LAT1-4F2hc cryo-EM structures and linked SLC3A2-driven amino acid supply to nucleotide pools and genome stability.","evidence":"Cryo-EM at 3.3 Å of LAT1-4F2hc; metabolomics and nucleoside rescue in CD98hc-KO cells; PTPRJ pulldown/degradation","pmids":["30867591","31575908","29805737"],"confidence":"High","gaps":["Conformational cycle of the full transport mechanism not complete","PTPRJ-driven degradation mechanism (Medium) not fully mapped"]},{"year":2021,"claim":"Captured inhibitor-bound transport conformations and identified SLC3A2 as a pathogen invasion receptor, broadening its functional scope.","evidence":"Inhibitor-bound LAT1-4F2hc cryo-EM at 2.7–2.8 Å; PvRBP2a MS/flow/binding/invasion assays","pmids":["33758168","34294905"],"confidence":"High","gaps":["Pharmacology of distinct light-chain complexes not generalized","Structural basis of PvRBP2a binding not resolved"]},{"year":2022,"claim":"Defined N-glycosylation as a stability/trafficking requirement and identified polarity-complex and receptor partnerships controlling localization and function.","evidence":"Quadruple N-glycosylation mutants with biotinylation/BFA assays; SCRIB/LLGL2 quaternary complex co-IP/PLA; AGR2 receptor co-IP with xCT/RhoA readouts","pmids":["36028562","35501367","35086885"],"confidence":"High","gaps":["SCRIB and AGR2 findings are single-lab (Medium)","Which glycans drive specific complexes unresolved"]},{"year":2023,"claim":"Established post-translational control of SLC3A2 membrane abundance by glycosyltransferases and ubiquitin machinery, dictating xCT-dependent ferroptosis outcomes.","evidence":"B3GNT3 glycoproteomics/KO; Skp2 K48-ubiquitination and Neu5Ac/p62 degradation studies with ferroptosis readouts","pmids":["37479744","39079969","37771765"],"confidence":"High","gaps":["Several degradation pathways are single-lab (Medium)","Cross-talk among Skp2, B3GNT3, p62 regulation not integrated"]},{"year":2024,"claim":"Placed SLC3A2 expression under transcriptional control of FOXC1 in endothelium, coupling its amino acid transport to mTOR-dependent angiogenesis.","evidence":"Endothelial Foxc1 conditional KO with retinal angiogenesis, mTOR readout and agonist rescue","pmids":["38755144"],"confidence":"High","gaps":["Direct FOXC1 binding to the SLC3A2 promoter not detailed here","Transport vs signaling contribution to angiogenesis not separated"]},{"year":null,"claim":"How the same heavy chain selects among light chains in a given cell, and how its transport, integrin-signaling, chaperone, and receptor functions are coordinately regulated, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking light-chain selection to physiological context","Quantitative partitioning of plasma-membrane vs lysosomal vs adhesion-site pools unknown","Integration of competing degradation pathways (Skp2, p62, PTPRJ) not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,2,4,5,20]},{"term_id":"GO:0140104","term_label":"molecular carrier activity","supporting_discovery_ids":[0,5,20]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,8,17,27,31]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[9,12,28]},{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[30,41]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[11,24,17]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,9,28,31]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[19]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[13,28]}],"pathway":[{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[0,2,4,5,20]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[9,10,13,18,28]},{"term_id":"R-HSA-1474244","term_label":"Extracellular matrix organization","supporting_discovery_ids":[13]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[20,34,35,36]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[14,21]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[39,19,21]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,31,34,35]}],"complexes":["4F2hc/LAT1 (SLC7A5) heteromeric amino acid transporter","4F2hc/xCT (SLC7A11) system Xc-","SCRIB/SLC3A2/LLGL2/SLC7A5 quaternary complex","CD98hc/β1-integrin/TRPV4 focal adhesion complex"],"partners":["SLC7A5","SLC7A11","ITGB1","ITGB3","SLC2A1","LAPTM4B","TRPV4","SCRIB"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P08195","full_name":"Amino acid transporter heavy chain SLC3A2","aliases":["4F2 cell-surface antigen heavy chain","4F2hc","4F2 heavy chain antigen","Lymphocyte activation antigen 4F2 large subunit","Solute carrier family 3 member 2"],"length_aa":529,"mass_kda":57.9,"function":"Acts as a chaperone that facilitates biogenesis and trafficking of functional transporters heterodimers to the plasma membrane. Forms heterodimer with SLC7 family transporters (SLC7A5, SLC7A6, SLC7A7, SLC7A8, SLC7A10 and SLC7A11), a group of amino-acid antiporters (PubMed:10574970, PubMed:10903140, PubMed:11557028, PubMed:30867591, PubMed:33298890, PubMed:33758168, PubMed:34880232, PubMed:9751058, PubMed:9829974, PubMed:9878049). Heterodimers function as amino acids exchangers, the specificity of the substrate depending on the SLC7A subunit. Heterodimers SLC3A2/SLC7A6 or SLC3A2/SLC7A7 mediate the uptake of dibasic amino acids (PubMed:10903140, PubMed:9829974). Heterodimer SLC3A2/SLC7A11 functions as an antiporter by mediating the exchange of extracellular anionic L-cystine and intracellular L-glutamate across the cellular plasma membrane (PubMed:34880232). SLC3A2/SLC7A10 translocates small neutral L- and D-amino acids across the plasma membrane (By similarity). SLC3A2/SLC75 or SLC3A2/SLC7A8 translocates neutral amino acids with broad specificity, thyroid hormones and L-DOPA (PubMed:10574970, PubMed:11389679, PubMed:11557028, PubMed:11564694, PubMed:11742812, PubMed:12117417, PubMed:12225859, PubMed:12716892, PubMed:15980244, PubMed:30867591, PubMed:33298890, PubMed:33758168). SLC3A2 is essential for plasma membrane localization, stability, and the transport activity of SLC7A5 and SLC7A8 (PubMed:10391915, PubMed:10574970, PubMed:11311135, PubMed:15769744, PubMed:33066406). When associated with LAPTM4B, the heterodimer SLC7A5 is recruited to lysosomes to promote leucine uptake into these organelles, and thereby mediates mTORC1 activation (PubMed:25998567). Modulates integrin-related signaling and is essential for integrin-dependent cell spreading, migration and tumor progression (PubMed:11121428, PubMed:15625115) (Microbial infection) In case of hepatitis C virus/HCV infection, the complex formed by SLC3A2 and SLC7A5/LAT1 plays a role in HCV propagation by facilitating viral entry into host cell and increasing L-leucine uptake-mediated mTORC1 signaling activation, thereby contributing to HCV-mediated pathogenesis (Microbial infection) Acts as a receptor for malaria parasite Plasmodium vivax (Thai isolate) in immature red blood cells","subcellular_location":"Apical cell membrane; Cell membrane; Cell junction; Lysosome membrane; Melanosome; Basolateral cell membrane","url":"https://www.uniprot.org/uniprotkb/P08195/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SLC3A2","classification":"Not Classified","n_dependent_lines":502,"n_total_lines":1208,"dependency_fraction":0.4155629139072848},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SLC7A6","stoichiometry":10.0},{"gene":"ATP1A1","stoichiometry":0.2},{"gene":"CANX","stoichiometry":0.2},{"gene":"RAB11A","stoichiometry":0.2},{"gene":"SLC7A5","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/SLC3A2","total_profiled":1310},"omim":[{"mim_id":"614923","title":"BRANCHED-CHAIN KETO ACID DEHYDROGENASE KINASE DEFICIENCY; BCKDKD","url":"https://www.omim.org/entry/614923"},{"mim_id":"611627","title":"TLC DOMAIN-CONTAINING PROTEIN 3A; TLCD3A","url":"https://www.omim.org/entry/611627"},{"mim_id":"607959","title":"SOLUTE CARRIER FAMILY 7 (CATIONIC AMINO ACID TRANSPORTER, y+ SYSTEM), MEMBER 10; SLC7A10","url":"https://www.omim.org/entry/607959"},{"mim_id":"607933","title":"SOLUTE CARRIER FAMILY 7 (CATIONIC AMINO ACID TRANSPORTER, y+ SYSTEM), MEMBER 11; SLC7A11","url":"https://www.omim.org/entry/607933"},{"mim_id":"604735","title":"UBIQUITIN-SPECIFIC PROTEASE 16; USP16","url":"https://www.omim.org/entry/604735"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SLC3A2"},"hgnc":{"alias_symbol":["4T2HC","4F2","NACAE","CD98","CD98HC","4F2HC"],"prev_symbol":["MDU1"]},"alphafold":{"accession":"P08195","domains":[{"cath_id":"3.20.20.80","chopping":"220-533","consensus_level":"medium","plddt":94.2327,"start":220,"end":533},{"cath_id":"2.60.40.1180","chopping":"538-630","consensus_level":"medium","plddt":92.32,"start":538,"end":630}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P08195","model_url":"https://alphafold.ebi.ac.uk/files/AF-P08195-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P08195-F1-predicted_aligned_error_v6.png","plddt_mean":78.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SLC3A2","jax_strain_url":"https://www.jax.org/strain/search?query=SLC3A2"},"sequence":{"accession":"P08195","fasta_url":"https://rest.uniprot.org/uniprotkb/P08195.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P08195/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P08195"}},"corpus_meta":[{"pmid":"9726963","id":"PMC_9726963","title":"Expression cloning and characterization of a transporter for large neutral amino acids activated by the heavy chain of 4F2 antigen (CD98).","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9726963","citation_count":940,"is_preprint":false},{"pmid":"9751058","id":"PMC_9751058","title":"Amino-acid transport by heterodimers of 4F2hc/CD98 and members of a permease family.","date":"1998","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/9751058","citation_count":478,"is_preprint":false},{"pmid":"10391915","id":"PMC_10391915","title":"Identification of a membrane protein, LAT-2, that Co-expresses with 4F2 heavy chain, an L-type amino acid transport activity with broad specificity for small and large zwitterionic amino acids.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10391915","citation_count":342,"is_preprint":false},{"pmid":"9915839","id":"PMC_9915839","title":"4F2 (CD98) heavy chain is associated covalently with an amino acid transporter and controls intracellular trafficking and membrane topology of 4F2 heterodimer.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9915839","citation_count":292,"is_preprint":false},{"pmid":"9829974","id":"PMC_9829974","title":"Identification and characterization of a membrane protein (y+L amino acid transporter-1) that associates with 4F2hc to encode the amino acid transport activity y+L. A candidate gene for lysinuric protein intolerance.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9829974","citation_count":286,"is_preprint":false},{"pmid":"30867591","id":"PMC_30867591","title":"Structure of the human LAT1-4F2hc heteromeric amino acid transporter complex.","date":"2019","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/30867591","citation_count":272,"is_preprint":false},{"pmid":"11011012","id":"PMC_11011012","title":"The 4F2hc/LAT1 complex transports L-DOPA across the blood-brain barrier.","date":"2000","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/11011012","citation_count":231,"is_preprint":false},{"pmid":"15625115","id":"PMC_15625115","title":"CD98hc (SLC3A2) mediates integrin signaling.","date":"2004","source":"Proceedings of the National Academy of Sciences of the United States of 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\"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct reconstitution in Xenopus oocytes, replicated across multiple independent labs (PMIDs 9726963, 9751058, 9915839)\",\n      \"pmids\": [\"9726963\", \"9751058\", \"9915839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"4F2hc (SLC3A2) cysteine 109 (Cys-109) forms a disulfide bond that covalently links the heavy chain to its light chain subunits; mutation C109S abolishes heterodimer formation and drastically reduces co-expressed amino acid transport activity.\",\n      \"method\": \"Site-directed mutagenesis, co-immunoprecipitation, transport assay in Xenopus oocytes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis with functional transport readout, replicated in multiple studies (PMIDs 9829974, 10897033, 9761775)\",\n      \"pmids\": [\"9829974\", \"10897033\", \"9761775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"4F2hc (SLC3A2) associates with y+LAT-1 to form a heterodimer mediating system y+L amino acid transport (cationic and neutral amino acids exchanged with sodium); this is the molecular basis of the y+L transport system.\",\n      \"method\": \"Functional co-expression in Xenopus oocytes, co-immunoprecipitation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — functional reconstitution, independently replicated (PMIDs 9829974, 10903140)\",\n      \"pmids\": [\"9829974\", \"10903140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"SLC3A2 (4F2hc) controls intracellular trafficking and plasma membrane localization of its light chain partners: 4F2hc reaches the plasma membrane alone, but the light chain (LAT1) requires 4F2hc for surface expression. In cells expressing cadherins, 4F2hc is selectively localized to cell-cell adhesion sites.\",\n      \"method\": \"Mammalian cell transfection, immunofluorescence, flow cytometry\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (transfection, immunofluorescence, cell fractionation), replicated across labs\",\n      \"pmids\": [\"9915839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"LAT-2 co-expressed with 4F2hc (SLC3A2) mediates Na+-independent, broad-specificity system L transport of small and large zwitterionic amino acids via an exchanger mechanism; LAT-2 alone has intracellular location and no transport activity.\",\n      \"method\": \"Functional co-expression in Xenopus oocytes, tagged protein localization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution with localization and transport data, replicated (PMID 10391915, 11311135)\",\n      \"pmids\": [\"10391915\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The 4F2hc/y+LAT2 heterodimer mediates arginine efflux in exchange for extracellular glutamine and leucine (antiport mechanism); arginine has the highest affinity for the intracellular binding site, making arginine release the main physiological function.\",\n      \"method\": \"Functional reconstitution in Xenopus oocytes, radiolabeled amino acid transport assays\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — detailed in vitro transport characterization with substrate competition in oocytes, single lab\",\n      \"pmids\": [\"10903140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The cytoplasmic and transmembrane domains of CD98hc (SLC3A2) are required for its effects on integrin function, while the extracellular domain is required for stimulation of amino acid (isoleucine) transport; these two functions are separable and require distinct domains.\",\n      \"method\": \"CD98hc/CD69 chimera construction, isoleucine transport assays, integrin signaling readouts in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — domain dissection via chimeras with both functional transport and signaling readouts, single lab\",\n      \"pmids\": [\"11121428\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The 4F2hc/LAT1 heterodimeric complex mediates Na+-independent L-DOPA transport across the blood-brain barrier; LAT1 is predominantly expressed in brain microvessels and forms a heterodimer with 4F2hc in brain capillary endothelial cells.\",\n      \"method\": \"Northern hybridization, immunoblotting, radiolabeled L-DOPA uptake assay, immunohistochemistry\",\n      \"journal\": \"Brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple methods (protein expression, functional uptake assay, localization), single lab\",\n      \"pmids\": [\"11011012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The extracellular domain of 4F2hc (SLC3A2) is specifically required for surface expression of LAT2 and y+LAT2 but not LAT1; truncated 4F2hc containing only the cytosolic N-terminus and transmembrane helix retains partial ability to promote LAT1 surface expression.\",\n      \"method\": \"C-terminal truncation mutants of 4F2hc co-expressed with light chains in Xenopus oocytes and mammalian cells\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — systematic deletion mutagenesis with functional surface-expression readout, multiple light chains tested\",\n      \"pmids\": [\"11311135\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CD98hc (SLC3A2) physically associates with β1 integrins and is required for integrin-dependent cell spreading, migration, and protection from apoptosis; loss of CD98hc impairs adhesion-induced Akt and Rac GTPase activation. A CD98hc mutant that interacts with β1 integrins but not light chains restores integrin signaling, showing amino acid transport is dispensable for these functions.\",\n      \"method\": \"Gene knockout (CD98hc-null cells), rescue with domain mutants, cell spreading/migration assays, Akt/Rac activation assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with domain-specific rescue, multiple orthogonal functional readouts, single lab\",\n      \"pmids\": [\"15625115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"CD98hc (SLC3A2) interaction with β1 integrins requires its transmembrane domain (amino acids 82-87); this association drives FAK-dependent PI3K activation and cellular transformation (anchorage-independent growth).\",\n      \"method\": \"CD98hc/CD69 chimeras, co-immunoprecipitation, PI3K activation assays, soft-agar colony formation, xenograft tumor assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — domain mapping with chimeras, functional transformation assay and signaling, replicated findings\",\n      \"pmids\": [\"15485886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of the 4F2hc (SLC3A2) ectodomain reveals a (βα)8 barrel and antiparallel β sandwich related to bacterial α-glycosidases but lacking catalytic residues; Cys109 is located near the transmembrane domain and participates in a disulfide-linked homodimer at the cell surface.\",\n      \"method\": \"X-ray crystallography (2.1 Å and 2.8 Å crystal forms), cross-linking experiments, cell surface homodimerization assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution crystal structure with biochemical validation of homodimerization and Cys109 positioning\",\n      \"pmids\": [\"17724034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CD98hc (SLC3A2) interacts with integrin β cytoplasmic domain via the C-terminal 8 residues of β3 (Thr755–Thr762); point mutations T755K or T758M in β3 abolish CD98hc association and impair integrin-mediated cell spreading.\",\n      \"method\": \"Homology scanning mutagenesis, co-immunoprecipitation, cell spreading assays with Drosophila βPS gain-of-function mutations\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal gain/loss-of-function mutagenesis on both interacting proteins with functional cellular readouts\",\n      \"pmids\": [\"17597067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CD98hc (SLC3A2) participates in fibronectin matrix assembly by enabling RhoA GTPase activation downstream of integrins; CD98hc is not required for Fn biosynthesis or integrin repertoire/affinity but is required for force generation on the matrix.\",\n      \"method\": \"CD98hc knockout cells, fibronectin matrix assembly assay, RhoA activity assay, in vitro and in vivo matrix assembly\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with specific mechanistic rescue, multiple functional readouts including RhoA activation\",\n      \"pmids\": [\"17682053\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"B cell-specific deletion of CD98hc (SLC3A2) abolishes B cell proliferation and plasma cell formation; the integrin-binding domain of CD98hc (not the amino acid transport function) is required for B cell proliferation, acting via Erk1/2 activation and p27 downregulation.\",\n      \"method\": \"B cell-specific conditional knockout, domain-specific rescue mutants, Erk1/2 activation assays, FACS cell cycle analysis\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with domain-specific functional rescue, signaling readouts, multiple methods\",\n      \"pmids\": [\"19270713\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"4F2hc (SLC3A2) stabilizes GLUT1 protein at the plasma membrane and increases glucose uptake; 4F2hc and GLUT1 physically associate (co-immunoprecipitation confirmed endogenously in mouse brain and HeLa cells), and 4F2hc overexpression or knockdown respectively increases or decreases GLUT1 protein stability without affecting GLUT1 mRNA.\",\n      \"method\": \"Split-ubiquitin membrane yeast two-hybrid, co-immunoprecipitation, cycloheximide chase, radiolabeled glucose uptake assay, siRNA knockdown\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP confirmed endogenously, protein stability chase, functional glucose uptake assay, single lab\",\n      \"pmids\": [\"21270293\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"4F2hc (SLC3A2) silencing in HeLa cells impairs FAK/Akt/ERK1/2 integrin signaling, reduces MMP-2 expression/activity, and allows galectin-3 accumulation that cannot signal due to impaired 4F2hc interaction; loss of 4F2hc disrupts 4F2hc/β1-integrin/CD147 heterocomplexes, leading to β-catenin proteasomal degradation.\",\n      \"method\": \"Stable miRNA-mediated silencing, co-immunoprecipitation, FAK/Akt/ERK phosphorylation assays, MMP-2 activity assay, xenograft tumor model\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — stable KD with multiple downstream signaling readouts, single lab\",\n      \"pmids\": [\"23651923\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"4F2hc (SLC3A2) extracellular domain covers the extracellular face of the LAT2 light chain and stabilizes it in detergent-solubilized membranes; the 4F2hc ectodomain alone is sufficient to stabilize LAT2 and allows functional reconstitution in proteoliposomes.\",\n      \"method\": \"Transmission electron microscopy single-particle analysis, docking, crosslinking, proteoliposome reconstitution, stability assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — EM structural analysis combined with biochemical stabilization and functional reconstitution, single lab\",\n      \"pmids\": [\"24516142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CD98hc (SLC3A2) loss protects against Ras-driven skin carcinogenesis; CD98hc mediates stiffness sensing by increasing Rho kinase (ROCK) activity and YAP/TAZ-mediated transcription in response to matrix rigidity, amplifying a positive feedback loop that increases ECM stiffness.\",\n      \"method\": \"Conditional KO mouse model, chemical carcinogenesis, tumor regression after inducible deletion, RhoA/ROCK activity assays, YAP/TAZ reporter\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic model with mechanistic signaling readouts (ROCK/YAP/TAZ), both prevention and regression demonstrated\",\n      \"pmids\": [\"25267066\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The lysosomal protein LAPTM4b binds LAT1-4F2hc (SLC7A5-SLC3A2) and recruits this complex to lysosomes, enabling leucine uptake into lysosomes and mTORC1 activation via V-ATPase stimulation.\",\n      \"method\": \"Co-immunoprecipitation, lysosomal fractionation, leucine uptake assays, mTORC1 activation (S6K phosphorylation), LAPTM4b knockdown\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal pulldown, subcellular fractionation, functional mTORC1 signaling assay, single lab\",\n      \"pmids\": [\"25998567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CD98hc-associated transporters (xCT, LAT1, y+LAT2) control reactive oxygen species and intracellular amino acid levels; CD98hc deletion causes ferroptosis due to inability to compensate CD98hc/xCT loss. CD98hc amino acid transport (not integrin signaling) is required for in vitro cell proliferation.\",\n      \"method\": \"CD98hc chimeric mutant rescue experiments, ROS measurement, GSH assay, β-mercaptoethanol rescue, ferroptosis inhibitor rescue\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — domain uncoupling with functional chimeras, multiple metabolic readouts, ferroptosis rescue experiments\",\n      \"pmids\": [\"26945935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Slc3a2 is required for maintenance of Foxp3+ regulatory T cells in vivo; Slc3a2-deficient Treg cells show impaired isoleucine-induced mTORC1 activation and altered metabolic state, and Slc3a2-specific Treg KO mice develop multi-organ inflammation.\",\n      \"method\": \"Treg-specific conditional knockout, in vivo proliferation assays, mTORC1 activation (S6K/4EBP1), metabolic profiling, BCAA-reduced diet experiments\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic KO with mechanistic mTORC1 signaling and metabolic readouts, in vivo phenotype\",\n      \"pmids\": [\"29141216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LAT1 stabilizes 4F2hc (SLC3A2) protein via a chaperone-like function in trophoblastic cells; LAT1 knockout drastically reduces 4F2hc protein (but not mRNA) and prevents syncytiotrophoblast formation, because 4F2hc has fusogenic activity required for trophoblast cell fusion.\",\n      \"method\": \"LAT1 knockout mice, trophoblast LAT1 knockdown (BeWo cells), western blot for 4F2hc, forskolin-induced cell fusion assay\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with in vitro knockdown corroboration, protein stability and cell fusion functional readouts\",\n      \"pmids\": [\"28320871\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CD98hc (SLC3A2) regulates integrin mechanosensing via sphingolipid biosynthesis: loss of CD98hc decreases sphingolipid availability, preventing membrane recruitment and activation of Src kinases and GEF-H1, and impairing RhoA activation in response to matrix rigidity.\",\n      \"method\": \"Conditional KO in dermal cells, sphingolipid profiling (lipidomics), DES2 expression analysis, RhoA/Src/GEF-H1 activity assays, rescue with sphingolipid supplementation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with lipidomic profiling and targeted mechanistic rescue, in vivo and in vitro readouts\",\n      \"pmids\": [\"30451822\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Cryo-EM structure of human LAT1-4F2hc (SLC7A5-SLC3A2) heterodimer at 3.3 Å resolution reveals that besides the disulfide bond, LAT1 interacts extensively with 4F2hc on the extracellular side, within the membrane, and on the intracellular side; 4F2hc is essential for transport activity of the complex; LAT1 is in inward-open conformation.\",\n      \"method\": \"Cryo-electron microscopy (3.3 Å and 3.5 Å), inhibitor-bound structure, biochemical transport activity assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — near-atomic resolution cryo-EM structure with biochemical validation, independent replication (PMID 33758168)\",\n      \"pmids\": [\"30867591\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CD98hc (SLC3A2) deficiency causes replicative stress by reducing BCAA/aromatic amino acid availability, which diminishes glucose uptake/glycolysis, pentose phosphate pathway activity, and nucleotide pool; nucleoside supplementation rescues S-phase delay and proliferation defects.\",\n      \"method\": \"CD98hc KO cells, metabolomics, nucleotide pool measurement, DNA damage response (γH2AX), S-phase analysis by BrdU, nucleoside rescue\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with metabolomics and mechanistic nucleoside rescue, multiple orthogonal assays\",\n      \"pmids\": [\"31575908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PTPRJ receptor tyrosine phosphatase physically interacts with CD98hc (SLC3A2) and promotes its proteasomal degradation; PTPRJ overexpression reduces CD98hc protein levels, and proteasome inhibitor MG132 reverses this.\",\n      \"method\": \"Proteomic pulldown, co-immunoprecipitation, proteasome inhibitor rescue, PTPRJ overexpression in lung cancer cells\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus pharmacological rescue, single lab\",\n      \"pmids\": [\"29805737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"4F2hc modulates the substrate affinity and specificity of its light chains LAT1 and LAT2; light chains are functional transporters without 4F2hc in Pichia pastoris, but association with 4F2hc alters their kinetic properties.\",\n      \"method\": \"Heterologous expression in Pichia pastoris, radiolabeled amino acid transport assays comparing HAT complexes vs light chains alone\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstituted transport assay in yeast expression system, novel functional observation, single lab\",\n      \"pmids\": [\"33066406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CD98hc (SLC3A2) forms a molecular complex with β1 integrin and TRPV4 in focal adhesions; CD98hc knockdown inhibits TRPV4-mediated calcium influx induced by mechanical forces (but not by chemical activators); force must be transmitted from β1 integrin C-terminus via CD98hc cytoplasmic tail to the ankyrin repeat domain of TRPV4 for ultra-rapid mechanotransduction.\",\n      \"method\": \"Co-immunoprecipitation, co-localization imaging, CD98hc siRNA knockdown, calcium imaging with force application vs. chemical TRPV4 activation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, knockdown with mechano-specific functional readout, single lab\",\n      \"pmids\": [\"32989042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structures of LAT1-4F2hc with potent inhibitors at 2.7–2.8 Å resolution reveal an outward-facing occluded conformation; inhibitors occupy the substrate binding pocket with tails wedged between the binding site and TM10 of LAT1, defining a distinct inhibition mechanism. A Diiodo-Tyr-bound structure reveals a possible intermediate between outward-occluded and outward-open states.\",\n      \"method\": \"Cryo-electron microscopy (2.7–3.4 Å), synthesis and IC50 measurement of inhibitors, transport assays\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — near-atomic resolution cryo-EM with multiple inhibitor-bound states, functional transport data\",\n      \"pmids\": [\"33758168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Plasmodium vivax merozoite surface protein PvRBP2a binds CD98hc (SLC3A2) on reticulocytes to mediate host cell invasion; CD98hc is expressed preferentially on immature reticulocytes (CD71+) and is a host receptor for P. vivax tropism.\",\n      \"method\": \"Mass spectrometry identification, flow cytometry, biochemical binding assays, parasite invasion inhibition assays\",\n      \"journal\": \"Nature microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (MS, flow cytometry, biochemical binding, invasion assay), single lab\",\n      \"pmids\": [\"34294905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"N-glycosylation of 4F2hc (SLC3A2) at Asn365, Asn381, Asn424, and Asn506 is required for its stability and trafficking to the plasma membrane; quadruple mutation of these sites severely impairs membrane trafficking and correlates with reduced LAT1 (SLC7A5) surface expression and transport activity.\",\n      \"method\": \"Site-directed mutagenesis of all four N-glycosylation sites, biotinylation surface assay, brefeldin A trafficking assay, LAT1 co-expression and transport assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — systematic mutagenesis of all four glycosylation sites with trafficking and functional transport readouts\",\n      \"pmids\": [\"36028562\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The polarity protein SCRIB binds SLC3A2 N-terminus and facilitates formation of a SCRIB/SLC3A2/LLGL2/SLC7A5 quaternary complex required for membrane localization of the leucine transporter; both SCRIB and SLC3A2 are required for cell proliferation and tamoxifen resistance in ER+ breast cancer.\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation assay, siRNA knockdown of SCRIB and SLC3A2, membrane localization assay, cell proliferation assay\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with complex mapping and functional rescue, single lab\",\n      \"pmids\": [\"35501367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Tumour-associated neutrophil-secreted AGR2 binds CD98hc (SLC3A2) as its functional receptor; AGR2 increases xCT transporter activity in a CD98hc-dependent manner, subsequently activating the RhoA/ROCK2 cascade to promote CRC cell migration.\",\n      \"method\": \"Co-immunoprecipitation, neutrophil-specific Agr2 KO mice, xCT activity assay, RhoA/ROCK2 phosphorylation, in vitro migration assay, in vivo liver metastasis model\",\n      \"journal\": \"Gut\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, in vivo KO model, functional xCT and signaling assays, single lab\",\n      \"pmids\": [\"35086885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The glycosyltransferase B3GNT3 catalyzes N-glycosylation of 4F2hc (SLC3A2), stabilizes 4F2hc protein, and enhances interaction between 4F2hc and xCT; glycosylation-deficient 4F2hc fails to restore ferroptosis resistance and system Xc- activity in 4F2hc-deficient cells.\",\n      \"method\": \"N- and O-linked glycoproteomics, B3GNT3 KO, site-directed glycosylation mutants of 4F2hc, system Xc- activity (glutathione measurement), xenograft tumor model\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — glycoproteomic identification, KO and glycosylation mutagenesis with functional transport and ferroptosis readouts\",\n      \"pmids\": [\"37479744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Skp2 E3 ligase controls SLC3A2 membrane localization and cystine/glutamate exchange function via K48-linked ubiquitination of SLC3A2; in sepsis, MEK/ERK pathway suppresses Skp2, reducing K48-ubiquitination of SLC3A2, impairing its membrane localization and triggering ferroptosis in pulmonary epithelial cells.\",\n      \"method\": \"Skp2 KO/overexpression, ubiquitination assay (K48 linkage), membrane fractionation, cystine uptake assay, lung injury model, Skp2 mRNA-LNP rescue\",\n      \"journal\": \"Cellular and molecular life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ubiquitination assay with membrane localization and transport readout, in vivo model, single lab\",\n      \"pmids\": [\"39079969\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Neu5Ac (N-acetylneuraminic acid) promotes SLC3A2 binding to ubiquitin and p62-mediated degradation, leading to lipid peroxide accumulation and ferroptosis in vascular endothelial cells.\",\n      \"method\": \"Co-immunoprecipitation of SLC3A2 with ubiquitin/p62, ferroptosis markers (lipid peroxidation, GSH), ApoE-/- atherosclerosis mouse model, Fer-1 rescue\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP ubiquitination evidence with in vivo model and ferroptosis rescue, single lab\",\n      \"pmids\": [\"37771765\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"FOXC1 transcription factor directly regulates endothelial Slc3a2 (and Slc7a5) expression; EC-specific Foxc1 deletion reduces SLC3A2/SLC7A5 expression, diminishes mTOR activity, and impairs retinal angiogenesis; mTOR agonist rescues the vascular growth defect.\",\n      \"method\": \"Endothelial-specific Foxc1 conditional KO, retinal angiogenesis assays, mTOR activity measurement, mTOR agonist rescue, OIR model\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with mechanistic mTOR signaling readout and pharmacological rescue, in vivo retinal model\",\n      \"pmids\": [\"38755144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The SLC3A2-NRG1 fusion protein (transmembrane domain of SLC3A2 fused to EGF-like domain of NRG1) binds ERBB3/ERBB4, promotes ERBB2-ERBB3 heterocomplex formation and phosphorylation, and activates PI3K/AKT and MAPK pathways, driving lung cancer cell proliferation.\",\n      \"method\": \"Ligand-receptor binding assays, co-immunoprecipitation of ERBB2/ERBB3, phosphorylation assays, colony formation, xenograft tumor model, siRNA targeting\",\n      \"journal\": \"Molecular cancer therapeutics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — binding assays, co-IP, signaling assays, in vitro and in vivo functional readouts for fusion oncogene\",\n      \"pmids\": [\"29959202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SLC3A2 functions upstream of mTOR1 in the unfolded protein response (UPR) in cardiomyocytes; SLC3A2 knockdown reduces activity of ATF4, ATF6, and XBP1 UPR sensors, and mTOR1 acts as mediator between SLC3A2 and UPR activation. SLC3A2 inhibition also enhances apoptosis.\",\n      \"method\": \"siRNA knockdown of SLC3A2 and mTOR1 in H9C2/PC12 cells, western blot for UPR markers, RNA sequencing, flow cytometry apoptosis assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA epistasis for UPR pathway, multiple downstream readouts, single lab\",\n      \"pmids\": [\"30592731\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Cryo-EM 3D-map (~13 Å) of human 4F2hc-LAT2 heterodimer places the 4F2hc ectodomain adjacent to the LAT2 transporter domain; the known 4F2hc ectodomain X-ray structure fits into the smaller density, revealing spatial relationship between subunits.\",\n      \"method\": \"Cryo-electron microscopy with Volta phase plate, single-particle analysis, fitting of X-ray ectodomain structure\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — structural EM map at limited resolution (~13 Å), single lab, no functional readout\",\n      \"pmids\": [\"30795505\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CD98 (SLC3A2/4F2hc) acts as a cell surface receptor for human β-defensin 3 (hBD3) internalization in epithelial cells; CD98 and hBD3 directly bind (mapped to CD98 residues 304-414 by surface plasmon resonance), and CD98 knockdown impairs hBD3 cell surface binding and internalization.\",\n      \"method\": \"FRET, surface plasmon resonance, co-localization, CD98 knockdown, internalization assay\",\n      \"journal\": \"Chemistry & biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay (SPR) and loss-of-function with internalization readout, single lab\",\n      \"pmids\": [\"25641165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Transformation of BALB3T3 fibroblasts by CD98hc (SLC3A2) overexpression requires disulfide-linked association with CD98 light chain via Cys103 of the heavy chain; C103S mutation abolishes both light chain association and transformation activity, while C325S retains both.\",\n      \"method\": \"Stable transfection of wild-type and cysteine mutant CD98hc, immunoprecipitation for heterodimer detection, soft-agar colony formation, xenograft tumor assay\",\n      \"journal\": \"International journal of cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic Cys mutagenesis with co-IP and functional transformation assay, mechanistically informative\",\n      \"pmids\": [\"10897033\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SLC3A2 (4F2hc/CD98hc) is a type II membrane glycoprotein that functions as the obligatory heavy chain subunit of heteromeric amino acid transporters (HATs): it covalently associates via a Cys109 disulfide bond with one of multiple light chain subunits (LAT1, LAT2, y+LAT1, y+LAT2, xCT, b0,+AT) to form distinct transport complexes with different substrate specificities, controls light chain trafficking to the plasma membrane, stabilizes light chains, and modulates their substrate affinity; structurally, its (βα)8 barrel ectodomain covers the extracellular face of the light chain and makes extensive contacts within and below the membrane as revealed by cryo-EM; independently of transport, SLC3A2 interacts via its transmembrane/cytoplasmic domains with β1 integrin cytoplasmic tails, mediating integrin-dependent Akt/Rac/RhoA/FAK signaling that drives cell spreading, proliferation, survival, mechanosensing, and matrix assembly; it also stabilizes GLUT1, acts upstream of mTORC1 and the UPR, and its N-glycosylation is required for protein stability and plasma membrane trafficking.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SLC3A2 (4F2hc/CD98hc) is a type II membrane glycoprotein that serves as the obligatory heavy-chain subunit of heteromeric amino acid transporters, pairing with multiple light chains to assemble transport systems of distinct substrate specificity, while independently coupling integrins to mechanosignaling [#0, #9]. It covalently links to its light-chain partners through a Cys109 disulfide bond, and loss of this cysteine abolishes heterodimer formation and transport [#1]. Through this association SLC3A2 reconstitutes system L transport with LAT1 and LAT2 (large/small neutral amino acids), system y+L transport with y+LAT-1 and y+LAT2 (cationic/neutral amino acid antiport), and cystine/glutamate exchange with xCT [#0, #2, #4, #5, #20]. SLC3A2 controls the intracellular trafficking, plasma-membrane delivery, and stability of its light chains and modulates their substrate affinity, while its own surface delivery and stability depend on N-glycosylation at Asn365/381/424/506 [#3, #8, #27, #31]. Structurally, its (\\u03b2\\u03b1)8-barrel ectodomain — related to bacterial \\u03b1-glycosidases but catalytically dead — covers the extracellular face of the light chain and makes extensive contacts across the membrane and on the intracellular side, as resolved by crystallography and cryo-EM of the LAT1-4F2hc complex [#11, #17, #24]. Independently of transport, SLC3A2 binds \\u03b21/\\u03b23 integrin cytoplasmic tails via its transmembrane/cytoplasmic domains and drives integrin-dependent Akt, Rac, RhoA, FAK and PI3K signaling that controls cell spreading, migration, survival, proliferation, fibronectin matrix assembly, and stiffness-dependent mechanosensing through ROCK and YAP/TAZ [#6, #9, #10, #12, #13, #18]. Its amino-acid transport function feeds anabolic and redox programs: leucine/isoleucine uptake activates mTORC1 (including at the lysosome via LAPTM4b) to sustain regulatory T-cell maintenance and angiogenesis, while xCT-mediated cystine import maintains glutathione and protects against ferroptosis [#19, #20, #21, #37]. SLC3A2 abundance is set post-translationally by ubiquitin ligases and glycosyltransferases (Skp2, B3GNT3, PTPRJ, p62) that gate its membrane localization and ferroptosis-relevant activity [#26, #34, #35, #36]. SLC3A2 additionally acts as a cell-surface receptor co-opted by Plasmodium vivax PvRBP2a and human \\u03b2-defensin 3, and an SLC3A2-NRG1 transmembrane fusion drives ERBB-dependent oncogenic signaling [#30, #41, #38].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established that SLC3A2 is the obligatory heavy chain enabling functional surface amino acid transport, defining its core role as a transporter assembly subunit rather than a transporter itself.\",\n      \"evidence\": \"Expression cloning and functional reconstitution of LAT1 with 4F2hc in Xenopus oocytes\",\n      \"pmids\": [\"9726963\", \"9751058\", \"9915839\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether 4F2hc contributes transport residues or only chaperones the light chain\", \"Substrate selectivity determinants not mapped\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Identified the covalent basis of heavy/light chain pairing, showing a single disulfide bond is required for complex assembly and transport.\",\n      \"evidence\": \"C109S site-directed mutagenesis with co-IP and transport assays in oocytes\",\n      \"pmids\": [\"9829974\", \"10897033\", \"9761775\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish the order of folding/assembly relative to disulfide formation\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Showed a single heavy chain pairs with multiple light chains to generate different transport systems, explaining how one gene supports diverse amino acid fluxes.\",\n      \"evidence\": \"Functional co-expression of 4F2hc with y+LAT-1 (and later LAT2, y+LAT2, xCT) in oocytes\",\n      \"pmids\": [\"9829974\", \"10903140\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-level pairing preferences not defined\", \"Did not address how a cell selects which light chain to assemble\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Separated SLC3A2's transport and integrin functions onto distinct domains, revealing it as a bifunctional protein.\",\n      \"evidence\": \"CD98hc/CD69 chimeras with isoleucine transport and integrin signaling readouts; cysteine mutants in transformation assays\",\n      \"pmids\": [\"11121428\", \"10897033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the direct integrin-tail contact residues at this stage\", \"Downstream effectors of the integrin function unmapped here\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrated genetically that the integrin-binding/signaling function, independent of amino acid transport, drives spreading, migration, and survival via Akt/Rac.\",\n      \"evidence\": \"CD98hc-null cells with transport-dead/integrin-competent rescue mutants and Akt/Rac assays; TM domain mapping and transformation assays\",\n      \"pmids\": [\"15625115\", \"15485886\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking integrin tail engagement to GTPase activation not fully resolved\", \"Did not address mechanotransduction directly\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined the structural fold of the ectodomain and the reciprocal integrin-tail interaction interface, and tied SLC3A2 to RhoA-driven matrix assembly.\",\n      \"evidence\": \"X-ray crystallography of the ectodomain; \\u03b23 tail mutagenesis with co-IP; CD98hc-KO fibronectin matrix assembly and RhoA assays\",\n      \"pmids\": [\"17724034\", \"17597067\", \"17682053\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ectodomain structure lacked the light chain and membrane context\", \"How RhoA activation is mechanically coupled was unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed the integrin-binding domain, not transport, is required for lymphocyte proliferation in vivo, generalizing the signaling function to immune development.\",\n      \"evidence\": \"B cell-specific conditional KO with domain rescue, Erk1/2 and p27 readouts\",\n      \"pmids\": [\"19270713\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not separate cell-intrinsic vs niche contributions fully\", \"Receptor input upstream of Erk1/2 not defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended SLC3A2's chaperone role beyond amino acid light chains by showing it stabilizes GLUT1 and boosts glucose uptake.\",\n      \"evidence\": \"Split-ubiquitin Y2H, endogenous reciprocal co-IP, cycloheximide chase, glucose uptake\",\n      \"pmids\": [\"21270293\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of GLUT1 stabilization unknown\", \"Whether the interaction is direct in the membrane not shown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided the membrane-context structure showing the ectodomain caps the light chain, and linked SLC3A2 to stiffness sensing via ROCK/YAP-TAZ in carcinogenesis.\",\n      \"evidence\": \"EM single-particle analysis and proteoliposome reconstitution of 4F2hc-LAT2; conditional KO carcinogenesis model with ROCK/YAP-TAZ readouts\",\n      \"pmids\": [\"24516142\", \"25267066\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"EM resolution insufficient for atomic contacts\", \"Feedback loop quantification incomplete\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected SLC3A2 transport activity to mTORC1 signaling and to redox homeostasis/ferroptosis protection, establishing two metabolic outputs.\",\n      \"evidence\": \"LAPTM4b co-IP, lysosomal fractionation and mTORC1 assays; CD98hc chimera rescue with ROS/GSH/ferroptosis readouts; \\u03b2-defensin 3 SPR binding\",\n      \"pmids\": [\"25998567\", \"26945935\", \"25641165\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How lysosomal vs plasma-membrane pools are partitioned unclear\", \"xCT-specific contribution vs other light chains not fully isolated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Resolved a lipid-based mechanism for SLC3A2 mechanosensing and identified a transmembrane fusion and UPR-coupling roles.\",\n      \"evidence\": \"Conditional KO with lipidomics and Src/GEF-H1/RhoA rescue; SLC3A2-NRG1 fusion binding/signaling assays; siRNA UPR epistasis in cardiomyocytes\",\n      \"pmids\": [\"30451822\", \"29959202\", \"30592731\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"UPR coupling shown only by knockdown epistasis (Medium)\", \"Direct lipid-binding by SLC3A2 not demonstrated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Delivered near-atomic LAT1-4F2hc cryo-EM structures and linked SLC3A2-driven amino acid supply to nucleotide pools and genome stability.\",\n      \"evidence\": \"Cryo-EM at 3.3 \\u00c5 of LAT1-4F2hc; metabolomics and nucleoside rescue in CD98hc-KO cells; PTPRJ pulldown/degradation\",\n      \"pmids\": [\"30867591\", \"31575908\", \"29805737\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conformational cycle of the full transport mechanism not complete\", \"PTPRJ-driven degradation mechanism (Medium) not fully mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Captured inhibitor-bound transport conformations and identified SLC3A2 as a pathogen invasion receptor, broadening its functional scope.\",\n      \"evidence\": \"Inhibitor-bound LAT1-4F2hc cryo-EM at 2.7\\u20132.8 \\u00c5; PvRBP2a MS/flow/binding/invasion assays\",\n      \"pmids\": [\"33758168\", \"34294905\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Pharmacology of distinct light-chain complexes not generalized\", \"Structural basis of PvRBP2a binding not resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined N-glycosylation as a stability/trafficking requirement and identified polarity-complex and receptor partnerships controlling localization and function.\",\n      \"evidence\": \"Quadruple N-glycosylation mutants with biotinylation/BFA assays; SCRIB/LLGL2 quaternary complex co-IP/PLA; AGR2 receptor co-IP with xCT/RhoA readouts\",\n      \"pmids\": [\"36028562\", \"35501367\", \"35086885\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SCRIB and AGR2 findings are single-lab (Medium)\", \"Which glycans drive specific complexes unresolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established post-translational control of SLC3A2 membrane abundance by glycosyltransferases and ubiquitin machinery, dictating xCT-dependent ferroptosis outcomes.\",\n      \"evidence\": \"B3GNT3 glycoproteomics/KO; Skp2 K48-ubiquitination and Neu5Ac/p62 degradation studies with ferroptosis readouts\",\n      \"pmids\": [\"37479744\", \"39079969\", \"37771765\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Several degradation pathways are single-lab (Medium)\", \"Cross-talk among Skp2, B3GNT3, p62 regulation not integrated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placed SLC3A2 expression under transcriptional control of FOXC1 in endothelium, coupling its amino acid transport to mTOR-dependent angiogenesis.\",\n      \"evidence\": \"Endothelial Foxc1 conditional KO with retinal angiogenesis, mTOR readout and agonist rescue\",\n      \"pmids\": [\"38755144\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct FOXC1 binding to the SLC3A2 promoter not detailed here\", \"Transport vs signaling contribution to angiogenesis not separated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the same heavy chain selects among light chains in a given cell, and how its transport, integrin-signaling, chaperone, and receptor functions are coordinately regulated, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking light-chain selection to physiological context\", \"Quantitative partitioning of plasma-membrane vs lysosomal vs adhesion-site pools unknown\", \"Integration of competing degradation pathways (Skp2, p62, PTPRJ) not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 2, 4, 5, 20]},\n      {\"term_id\": \"GO:0140104\", \"supporting_discovery_ids\": [0, 5, 20]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 8, 17, 27, 31]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [9, 12, 28]},\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [30, 41]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [11, 24, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 9, 28, 31]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [19]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [13, 28]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [0, 2, 4, 5, 20]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [9, 10, 13, 18, 28]},\n      {\"term_id\": \"R-HSA-1474244\", \"supporting_discovery_ids\": [13]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [20, 34, 35, 36]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [14, 21]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [39, 19, 21]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 31, 34, 35]}\n    ],\n    \"complexes\": [\n      \"4F2hc/LAT1 (SLC7A5) heteromeric amino acid transporter\",\n      \"4F2hc/xCT (SLC7A11) system Xc-\",\n      \"SCRIB/SLC3A2/LLGL2/SLC7A5 quaternary complex\",\n      \"CD98hc/\\u03b21-integrin/TRPV4 focal adhesion complex\"\n    ],\n    \"partners\": [\n      \"SLC7A5\",\n      \"SLC7A11\",\n      \"ITGB1\",\n      \"ITGB3\",\n      \"SLC2A1\",\n      \"LAPTM4b\",\n      \"TRPV4\",\n      \"SCRIB\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":9,"faith_total":9,"faith_pct":100.0}}