{"gene":"LAPTM5","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":1996,"finding":"LAPTM5 is a pentaspanning lysosomal transmembrane protein preferentially expressed in hematopoietic cells, localizing to lysosomes as determined by immunocytological and cell fractionation studies, and shows preliminary evidence of interaction with ubiquitin.","method":"Immunocytology, cell fractionation, cDNA cloning","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization by fractionation; ubiquitin interaction preliminary/single method","pmids":["8661146"],"is_preprint":false},{"year":2006,"finding":"LAPTM5 trafficking from the Golgi to the lysosome requires its PY motifs (L/PPxY) binding to Nedd4 WW domains and its UIM motif binding ubiquitinated GGA3; Nedd4 binding to LAPTM5 (not LAPTM5 ubiquitination) is required for lysosomal targeting, and Nedd4 can also ubiquitinate GGA3.","method":"Co-immunoprecipitation, RNAi knockdown, site-directed mutagenesis of PY and UIM motifs, subcellular localization imaging","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (mutagenesis, RNAi, coIP, localization), replicated across conditions","pmids":["17116753"],"is_preprint":false},{"year":2009,"finding":"Accumulation of LAPTM5 protein induces non-apoptotic, caspase-independent lysosomal cell death characterized by lysosomal membrane permeabilization (LMP), disruption of autophagic flux, and accumulation of autophagic vacuoles and p62/SQSTM1 in neuroblastoma cells.","method":"In vitro overexpression/restoration of LAPTM5 expression, lysosomal membrane permeabilization assay, autophagy flux analysis","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — defined cellular phenotype with multiple readouts in a single lab","pmids":["19787053"],"is_preprint":false},{"year":2011,"finding":"The HECT-type E3 ubiquitin ligase ITCH directly binds the PPxY motif of LAPTM5 via its WW domains and ubiquitinates LAPTM5 via its HECT domain, promoting LAPTM5 protein degradation; ITCH knockdown stabilizes LAPTM5 and enhances LAPTM5-mediated cell death.","method":"Co-immunoprecipitation, in vitro ubiquitination assay, siRNA knockdown, overexpression","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — direct binding, in vitro ubiquitination, and functional consequence demonstrated","pmids":["22009753"],"is_preprint":false},{"year":2012,"finding":"LAPTM5 is required for proinflammatory cytokine secretion in macrophages via TLR ligands; LAPTM5-deficient macrophages show reduced NF-κB and MAPK activation downstream of TNF receptor and pattern recognition receptors, reduced RIP1 ubiquitination, and upregulated A20 (a deubiquitinase of RIP1).","method":"LAPTM5 knockout mice, RNAi knockdown in RAW264.7 cells, NF-κB/MAPK signaling assays, cytokine secretion assays, ubiquitination assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — KO mice plus knockdown, multiple signaling readouts and mechanistic pathway placement","pmids":["22733818"],"is_preprint":false},{"year":2012,"finding":"LAPTM5 is a molecular partner of CD1e; the two proteins co-localize in trans-Golgi and late endosomal compartments, and their association increases under bafilomycin treatment, though LAPTM5 does not control CD1e ubiquitination or generation of soluble lysosomal CD1e.","method":"Co-immunoprecipitation, mass spectrometry identification, confocal co-localization","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, coIP and colocalization with partial functional follow-up","pmids":["22880058"],"is_preprint":false},{"year":2014,"finding":"LAPTM5 promotes lysosomal translocation of newly synthesized intracellular CD3ζ (targeting it from the Golgi) but not cell-surface CD3ζ from the mature TCR complex; this pathway is independent of TCR signaling-triggered tyrosine phosphorylation of CD3ζ and operates via a distinct genetic pathway from SLAP/c-Cbl-mediated degradation.","method":"Subcellular localization kinetics, Golgi-localizing CD3ζ mutants, tyrosine-to-phenylalanine CD3ζ mutants, genetic epistasis (double knockdown/mutant analysis)","journal":"Immunology and cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — multiple mutagenesis approaches, kinetic localization studies, genetic epistasis","pmids":["24638062"],"is_preprint":false},{"year":2017,"finding":"Ectopic overexpression of LAPTM5 in HeLa cells localizes to lysosomes and induces apoptosis via Mcl-1 and Bid cleavage (by a lysosomal cathepsin-dependent pathway), Bak activation, mitochondrial membrane potential loss, and caspase-9/-8/-3 cascade; co-overexpression of Mcl-1 abrogates these events.","method":"GFP-LAPTM5 overexpression, flow cytometry, caspase activity assays, cathepsin inhibitor, mitochondrial membrane potential assay, western blotting","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal assays, rescue with Mcl-1, single lab","pmids":["28464033"],"is_preprint":false},{"year":2019,"finding":"LAPTM5 expression is transcriptionally activated by RUNX2, which directly binds the LAPTM5 promoter at position -1176 to -1171; LAPTM5 is involved in RANKL trafficking in osteoblastic cells, as LAPTM5 knockdown increases cytoplasmic and secreted RANKL and enhances osteoclast differentiation.","method":"Chromatin immunoprecipitation, dual-luciferase reporter assay, RUNX2 overexpression/silencing, RANKL trafficking assay, co-culture osteoclast differentiation assay","journal":"Molecular medicine reports","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus reporter assay confirms direct transcriptional activation; functional trafficking assay","pmids":["31545469"],"is_preprint":false},{"year":2020,"finding":"LAPTM5 suppresses CD40-mediated NF-κB activation in glioblastoma; LAPTM5 knockdown unleashes CD40-driven NF-κB signaling, leading to enhanced invasiveness, clonogenicity, and temozolomide resistance that is overcome by NF-κB inhibition.","method":"RNAi knockdown in glioma cell lines, expression arrays, NF-κB inhibition rescue, in vitro and in vivo invasion/clonogenicity assays","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic knockdown with NF-κB inhibitor rescue and multiple functional readouts","pmids":["32582531"],"is_preprint":false},{"year":2021,"finding":"HIV-1 Vpr counteracts LAPTM5 restriction by triggering LAPTM5 degradation via DCAF1; LAPTM5 inhibits HIV-1 particle infectivity by transporting HIV-1 envelope glycoproteins to lysosomes for degradation; LAPTM5 silencing phenocopies Vpr in macrophages, and LAPTM5 re-expression in CD4+ T cells reconstitutes Vpr-dependent HIV-1 infection enhancement.","method":"Viral infection assays, LAPTM5 knockdown/overexpression, Vpr mutant analysis, DCAF1 dependency assays, envelope glycoprotein trafficking to lysosomes","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal approaches including phenocopy, re-expression rescue, and mechanistic trafficking assay","pmids":["34140527"],"is_preprint":false},{"year":2022,"finding":"BCR stimulation upregulates LAPTM5, which triggers immature B cell apoptosis through two mechanisms: (1) promoting BCR internalization, reducing SYK and ERK phosphorylation; and (2) targeting the E3 ubiquitin ligase WWP2 for lysosomal degradation, causing PTEN accumulation, suppressed AKT phosphorylation, increased FOXO1/p27Kip1/BIM expression. LAPTM5 deficiency exacerbates autoantibody production in vivo.","method":"BCR stimulation assays, LAPTM5 knockout mice, co-immunoprecipitation, western blotting for signaling pathway components, flow cytometry for BCR internalization, in vivo autoantibody measurement","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — two mechanistic pathways defined by multiple orthogonal methods plus in vivo KO validation","pmids":["36037365"],"is_preprint":false},{"year":2022,"finding":"The lncRNA LCDR binds hnRNP K to stabilize LAPTM5 mRNA, maintaining lysosomal membrane integrity; knockdown of LCDR, hnRNP K, or LAPTM5 each promotes lysosomal membrane permeabilization and lysosomal cell death/apoptosis in lung cancer cells; LAPTM5 overexpression or cathepsin B inhibition partially rescues these effects.","method":"RNA pulldown, RIP-qPCR, siRNA knockdown, LAPTM5 overexpression rescue, lysosomal membrane permeabilization assay, in vivo xenograft","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, rescue experiments, and in vivo validation","pmids":["35091468"],"is_preprint":false},{"year":2023,"finding":"c-Myc trans-represses LAPTM5 transcription by binding two E-boxes in the LAPTM5 promoter; Myc also trans-activates miR-17-3p, which binds 11 sites in LAPTM5 3'UTR to suppress LAPTM5 protein synthesis, further dampening tumor-suppressive LAPTM5 in B-lymphomas.","method":"Promoter binding assays (E-box mutagenesis), miRNA target site analysis, reporter assays, functional growth assays","journal":"Annals of hematology","confidence":"Medium","confidence_rationale":"Tier 2 — direct promoter binding and miRNA target site demonstrated; single lab","pmids":["37713124"],"is_preprint":false},{"year":2025,"finding":"LAPTM5 competes with LAMP1 for binding to the E3 ubiquitin ligase WWP2, thereby inhibiting LAMP1 ubiquitination and degradation to preserve lysosomal membrane stability and sustain autophagic flux, conferring cisplatin resistance in NSCLC; LAPTM5 knockdown increases lysosomal membrane permeability, releases cathepsin D, elevates ROS, and accelerates cell death.","method":"Co-immunoprecipitation, LAPTM5 knockdown, cathepsin D release assay, ROS measurement, autophagic flux assay, western blotting","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — competitive binding mechanism supported by coIP and functional assays; single lab","pmids":["40280227"],"is_preprint":false},{"year":2025,"finding":"LAPTM5 associates with STING, represses its K48- and K63-linked polyubiquitination, preventing both proteasomal and lysosomal degradation of STING, thereby maintaining STING protein stability; LAPTM5 knockdown reduces STING protein levels and downstream inflammatory signaling in macrophages.","method":"Co-immunoprecipitation, ubiquitination assays (K48/K63 linkage-specific), LAPTM5 knockdown, STING signaling assays","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 — direct interaction and mechanistic ubiquitination suppression demonstrated; single lab","pmids":["41087666"],"is_preprint":false},{"year":2026,"finding":"Ginkgetin inhibits K48-linked ubiquitination of LAPTM5 at residues K86 and K122 by targeting Ube3c (ubiquitin-protein ligase E3C), thereby increasing LAPTM5 protein levels, promoting autophagosome-lysosome fusion, and enabling autophagic degradation of TBK1 to suppress inflammatory signaling in macrophages during sepsis-induced acute lung injury.","method":"Co-immunoprecipitation, site-directed mutagenesis (K86/K122), biotin pulldown with mass spectrometry, DARTS, molecular docking, proteomics, autophagy flux assays","journal":"Phytomedicine","confidence":"High","confidence_rationale":"Tier 1-2 — ubiquitination site mapping by mutagenesis, direct target identification by pulldown/MS, functional assays in vitro and in vivo","pmids":["41666511"],"is_preprint":false},{"year":2026,"finding":"In AML, LAPTM5 promotes LAMP1 and LAMP2 transcription, supporting lysosomal biogenesis and autophagolysosome formation to sustain autophagic flux and reduce cytarabine-induced apoptosis; LAPTM5 knockdown impairs autophagolysosome formation and lysosomal biogenesis, sensitizing resistant AML cells to cytarabine in vitro and in vivo.","method":"scRNA-seq data analysis, LAPTM5 knockdown, autophagic flux assay, LAMP1/LAMP2 expression analysis, in vivo tumor model","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — knockdown with defined mechanistic pathway and in vivo validation; single lab","pmids":["41912486"],"is_preprint":false},{"year":2025,"finding":"WDFY4 interacts with LAPTM5 (validated by co-immunoprecipitation and immunofluorescence co-localization); WDFY4 interference inhibits LAPTM5 expression and activates the downstream CDC42/mTOR/4EBP1/SLC7A11 pathway, reducing ferroptosis; LAPTM5 overexpression rescues ferroptosis suppression caused by WDFY4 knockdown.","method":"Co-immunoprecipitation, immunofluorescence co-localization, WDFY4/LAPTM5 knockdown/overexpression, pathway analysis (CDC42/mTOR/4EBP1/SLC7A11), in vivo atherosclerosis model","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — direct interaction validated, epistasis by rescue experiment, in vivo model","pmids":["40755163"],"is_preprint":false}],"current_model":"LAPTM5 is a pentaspanning lysosomal transmembrane protein that uses its PY motifs to bind Nedd4/ITCH ubiquitin ligases and its UIM to recruit ubiquitinated GGA3, enabling Golgi-to-lysosome cargo sorting (including CD3ζ and BCR/TCR components) independent of its own ubiquitination; it maintains lysosomal membrane integrity by competing with LAMP1 for WWP2-mediated ubiquitination and by stabilizing STING against ubiquitin-dependent degradation; in immune cells it acts as a context-dependent regulator—promoting inflammatory NF-κB/MAPK signaling in macrophages via RIP1 ubiquitination, triggering immature B cell apoptosis through WWP2/PTEN/AKT/FOXO1 pathway and BCR internalization, and serving as a restriction factor for HIV-1 by routing envelope glycoproteins to lysosomal degradation."},"narrative":{"teleology":[{"year":1996,"claim":"Establishing the identity and subcellular home of LAPTM5 answered where in the cell this hematopoietic-restricted protein operates, placing it at lysosomes with preliminary ubiquitin association.","evidence":"cDNA cloning, immunocytology, and cell fractionation in hematopoietic cells","pmids":["8661146"],"confidence":"Medium","gaps":["Ubiquitin interaction was preliminary and lacked biochemical validation","No functional role established","Topology and membrane-spanning architecture not experimentally resolved"]},{"year":2006,"claim":"Defining the molecular logic of LAPTM5 trafficking revealed that PY-motif/Nedd4 binding and UIM/GGA3 interaction constitute two separable sorting signals for Golgi-to-lysosome transport, and that Nedd4 binding—not LAPTM5 ubiquitination—is the critical trafficking determinant.","evidence":"Mutagenesis of PY and UIM motifs, Nedd4 RNAi, co-immunoprecipitation, subcellular localization imaging","pmids":["17116753"],"confidence":"High","gaps":["Whether other Nedd4-family ligases substitute for Nedd4 in vivo","Structural basis of PY–WW domain recognition for LAPTM5 not determined","Cargo repertoire beyond LAPTM5 itself not yet identified"]},{"year":2009,"claim":"Demonstrating that LAPTM5 accumulation induces lysosomal membrane permeabilization and non-apoptotic cell death linked it to a lysosomal cell death pathway and hinted at a tumor-suppressive function.","evidence":"LAPTM5 overexpression/restoration in neuroblastoma cells, LMP assays, autophagy flux analysis","pmids":["19787053"],"confidence":"Medium","gaps":["Mechanism by which LAPTM5 triggers LMP was undefined","Physiological relevance in endogenous expression contexts unclear","Relationship between LAPTM5 levels and lysosomal membrane composition not explored"]},{"year":2011,"claim":"Identifying ITCH as a second HECT E3 that ubiquitinates and degrades LAPTM5 established a feedback mechanism controlling LAPTM5 protein levels and linked LAPTM5 turnover to cell death regulation.","evidence":"Co-immunoprecipitation, in vitro ubiquitination assay, siRNA knockdown of ITCH","pmids":["22009753"],"confidence":"High","gaps":["Relative contributions of ITCH vs Nedd4 to LAPTM5 turnover in different cell types unresolved","Whether ITCH-mediated degradation is proteasomal or lysosomal not clarified"]},{"year":2012,"claim":"Two studies expanded LAPTM5 function beyond trafficking: in macrophages, LAPTM5 promotes inflammatory NF-κB/MAPK signaling by sustaining RIP1 ubiquitination downstream of TLRs and TNF receptor; separately, LAPTM5 was identified as a molecular partner of CD1e in Golgi/endosomal compartments.","evidence":"LAPTM5 knockout mice and RAW264.7 knockdown with cytokine/signaling assays; co-IP/MS identification and confocal co-localization of CD1e–LAPTM5","pmids":["22733818","22880058"],"confidence":"High","gaps":["Direct mechanism by which LAPTM5 sustains RIP1 ubiquitination (e.g., does it sequester A20?) not biochemically resolved","Functional consequence of CD1e–LAPTM5 interaction on antigen presentation unclear"]},{"year":2014,"claim":"Showing that LAPTM5 selectively targets newly synthesized intracellular CD3ζ (but not surface TCR-associated CD3ζ) for lysosomal degradation identified a specific cargo and distinguished this pathway from SLAP/c-Cbl-mediated TCR downregulation.","evidence":"Golgi-localizing CD3ζ mutants, tyrosine-to-phenylalanine mutants, genetic epistasis analysis","pmids":["24638062"],"confidence":"High","gaps":["Whether LAPTM5 directly binds CD3ζ or acts through an adaptor not determined","Physiological impact on T cell development or activation thresholds not tested in vivo"]},{"year":2019,"claim":"Demonstrating that RUNX2 directly transactivates the LAPTM5 promoter and that LAPTM5 controls RANKL trafficking in osteoblasts extended its function beyond hematopoietic cells to bone biology.","evidence":"Chromatin immunoprecipitation, dual-luciferase reporter, RANKL trafficking and osteoclast differentiation assays","pmids":["31545469"],"confidence":"Medium","gaps":["In vivo bone phenotype of LAPTM5 deficiency not characterized","Whether LAPTM5 routes RANKL via the same PY/UIM-dependent mechanism as other cargoes not tested"]},{"year":2021,"claim":"Identifying LAPTM5 as a restriction factor for HIV-1—routing envelope glycoproteins to lysosomes for degradation—and showing that HIV-1 Vpr counteracts it via DCAF1-dependent LAPTM5 destruction revealed a virus–host arms race centered on lysosomal sorting.","evidence":"Viral infection assays with Vpr mutants, LAPTM5 knockdown/re-expression, DCAF1 dependency, envelope trafficking to lysosomes in macrophages and CD4+ T cells","pmids":["34140527"],"confidence":"High","gaps":["Whether LAPTM5 restricts other enveloped viruses not explored","Structural basis of Vpr–DCAF1–LAPTM5 ternary complex not resolved"]},{"year":2022,"claim":"Two parallel advances established LAPTM5's dual role in B cell tolerance and lysosomal membrane integrity: BCR-stimulated LAPTM5 promotes immature B cell apoptosis by internalizing BCR and degrading WWP2 (activating PTEN/AKT/FOXO1), while the lncRNA LCDR/hnRNP K axis stabilizes LAPTM5 mRNA to maintain lysosomal membrane integrity in cancer cells.","evidence":"LAPTM5 KO mice with autoantibody assays, BCR internalization/signaling pathway dissection; RNA pulldown, RIP-qPCR, LMP assays, in vivo xenograft rescue","pmids":["36037365","35091468"],"confidence":"High","gaps":["Whether LAPTM5-mediated WWP2 degradation requires its PY motifs not tested","How LAPTM5 physically maintains lysosomal membrane stability at the structural level remains unknown"]},{"year":2025,"claim":"Multiple studies refined LAPTM5's lysosomal-protective and signaling roles: LAPTM5 competes with LAMP1 for WWP2 binding to prevent LAMP1 degradation and preserve autophagic flux; LAPTM5 stabilizes STING by suppressing K48/K63-linked polyubiquitination; and WDFY4 interaction with LAPTM5 regulates ferroptosis through CDC42/mTOR signaling.","evidence":"Co-IP competition assays, linkage-specific ubiquitination assays, LAPTM5/WDFY4 epistasis with rescue, in vivo atherosclerosis and NSCLC models","pmids":["40280227","41087666","40755163"],"confidence":"Medium","gaps":["Competition model for LAMP1/LAPTM5/WWP2 awaits reconstitution with purified components","Mechanism by which LAPTM5 suppresses STING ubiquitination (direct shielding vs. recruiting a DUB) unknown","WDFY4–LAPTM5 interaction stoichiometry and structural basis not defined"]},{"year":2026,"claim":"Mapping K48-linked ubiquitination of LAPTM5 at K86 and K122 by Ube3c, and showing that stabilization of LAPTM5 promotes autophagosome–lysosome fusion and autophagic TBK1 degradation, established a druggable axis (targeted by ginkgetin) for controlling inflammation; separately, LAPTM5 was shown to promote LAMP1/LAMP2 transcription and lysosomal biogenesis to maintain autophagic flux and drug resistance in AML.","evidence":"Site-directed mutagenesis of K86/K122, biotin pulldown/MS target identification (Ube3c), autophagy flux assays in sepsis model; scRNA-seq, LAPTM5 knockdown, LAMP1/LAMP2 expression analysis, in vivo AML model","pmids":["41666511","41912486"],"confidence":"High","gaps":["Whether Ube3c is the primary E3 controlling LAPTM5 turnover in all cell types or context-specific","Mechanism by which LAPTM5 promotes LAMP1/LAMP2 transcription is undefined","In vivo validation of ginkgetin efficacy via LAPTM5-specific mechanisms needs genetic confirmation"]},{"year":null,"claim":"The structural basis of LAPTM5's pentaspanning architecture, how it physically stabilizes lysosomal membranes, and the complete cargo repertoire it sorts remain open questions; whether its opposing roles in inflammation (promoting NF-κB in macrophages vs. suppressing it in glioblastoma) reflect cell-type-specific interactors or distinct signaling complexes is unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of LAPTM5","No systematic cargo identification (e.g., proximity labeling)","Cell-type-specific interactome not mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,6,10,14]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,11,15]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[0,1,2,6,7,10,12,14]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[1,5,6]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[2,12,14,16,17]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[4,6,10,11]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[2,7,11,12]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,6,10]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,15,16]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,9,11]}],"complexes":[],"partners":["NEDD4","ITCH","GGA3","WWP2","STING1","WDFY4","UBE3C","CD1E"],"other_free_text":[]},"mechanistic_narrative":"LAPTM5 is a pentaspanning lysosomal transmembrane protein, preferentially expressed in hematopoietic cells, that functions as a central regulator of lysosomal cargo sorting, lysosomal membrane integrity, and immune cell signaling. Its Golgi-to-lysosome trafficking depends on PY motifs that recruit Nedd4-family HECT E3 ubiquitin ligases (Nedd4, ITCH) and a UIM that binds ubiquitinated GGA3, enabling it to route diverse cargoes—including newly synthesized CD3ζ, BCR components, HIV-1 envelope glycoproteins, and RANKL—to lysosomes for degradation [PMID:17116753, PMID:24638062, PMID:34140527, PMID:31545469]. LAPTM5 preserves lysosomal membrane stability by competing with LAMP1 for WWP2-mediated ubiquitination and by promoting LAMP1/LAMP2 expression and autophagolysosome formation, and it stabilizes STING by suppressing its K48/K63-linked polyubiquitination [PMID:40280227, PMID:41912486, PMID:41087666]. In immune cells, LAPTM5 has context-dependent roles: it promotes NF-κB/MAPK inflammatory signaling in macrophages through RIP1 ubiquitination, enforces negative selection of autoreactive immature B cells by internalizing BCR and degrading WWP2 to activate the PTEN/AKT/FOXO1 apoptotic axis, and restricts HIV-1 infectivity by targeting viral envelope glycoproteins for lysosomal degradation—a function counteracted by HIV-1 Vpr via DCAF1-dependent LAPTM5 destruction [PMID:22733818, PMID:36037365, PMID:34140527]."},"prefetch_data":{"uniprot":{"accession":"Q13571","full_name":"Lysosomal-associated transmembrane protein 5","aliases":["Lysosomal-associated multitransmembrane protein 5","Retinoic acid-inducible E3 protein"],"length_aa":262,"mass_kda":29.9,"function":"May have a special functional role during embryogenesis and in adult hematopoietic cells","subcellular_location":"Lysosome membrane","url":"https://www.uniprot.org/uniprotkb/Q13571/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LAPTM5","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/LAPTM5","total_profiled":1310},"omim":[{"mim_id":"608323","title":"CHARCOT-MARIE-TOOTH DISEASE, DOMINANT INTERMEDIATE C; CMTDIC","url":"https://www.omim.org/entry/608323"},{"mim_id":"601476","title":"LYSOSOME-ASSOCIATED PROTEIN, TRANSMEMBRANE 5; LAPTM5","url":"https://www.omim.org/entry/601476"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"bone marrow","ntpm":1214.0},{"tissue":"lymphoid tissue","ntpm":628.3}],"url":"https://www.proteinatlas.org/search/LAPTM5"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q13571","domains":[{"cath_id":"-","chopping":"9-45_61-163_180-229","consensus_level":"high","plddt":74.1996,"start":9,"end":229}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13571","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13571-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13571-F1-predicted_aligned_error_v6.png","plddt_mean":69.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LAPTM5","jax_strain_url":"https://www.jax.org/strain/search?query=LAPTM5"},"sequence":{"accession":"Q13571","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13571.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13571/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13571"}},"corpus_meta":[{"pmid":"17116753","id":"PMC_17116753","title":"Transport of LAPTM5 to lysosomes requires association with the ubiquitin ligase Nedd4, but not LAPTM5 ubiquitination.","date":"2006","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/17116753","citation_count":87,"is_preprint":false},{"pmid":"8661146","id":"PMC_8661146","title":"LAPTM5: a novel lysosomal-associated multispanning membrane protein preferentially expressed in hematopoietic cells.","date":"1996","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8661146","citation_count":80,"is_preprint":false},{"pmid":"22733818","id":"PMC_22733818","title":"LAPTM5 protein is a positive regulator of proinflammatory signaling pathways in macrophages.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22733818","citation_count":76,"is_preprint":false},{"pmid":"36037300","id":"PMC_36037300","title":"Genome-Scale CRISPR screen identifies LAPTM5 driving lenvatinib resistance in hepatocellular carcinoma.","date":"2022","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/36037300","citation_count":74,"is_preprint":false},{"pmid":"19787053","id":"PMC_19787053","title":"Lysosomal-associated protein multispanning transmembrane 5 gene (LAPTM5) is associated with spontaneous regression of neuroblastomas.","date":"2009","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/19787053","citation_count":46,"is_preprint":false},{"pmid":"35091468","id":"PMC_35091468","title":"LCDR regulates the integrity of lysosomal membrane by hnRNP K-stabilized LAPTM5 transcript and promotes cell survival.","date":"2022","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/35091468","citation_count":45,"is_preprint":false},{"pmid":"27922670","id":"PMC_27922670","title":"Downregulation of LAPTM5 suppresses cell proliferation and viability inducing cell cycle arrest at G0/G1 phase of bladder cancer cells.","date":"2016","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/27922670","citation_count":39,"is_preprint":false},{"pmid":"34140527","id":"PMC_34140527","title":"Vpr counteracts the restriction of LAPTM5 to promote HIV-1 infection in macrophages.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/34140527","citation_count":36,"is_preprint":false},{"pmid":"12527926","id":"PMC_12527926","title":"Stage-specific expression of Clast6/E3/LAPTM5 during B cell differentiation: elevated expression in human B lymphomas.","date":"2003","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/12527926","citation_count":27,"is_preprint":false},{"pmid":"12886255","id":"PMC_12886255","title":"Inactivation of the E3/LAPTm5 gene by chromosomal rearrangement and DNA methylation in human multiple myeloma.","date":"2003","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/12886255","citation_count":26,"is_preprint":false},{"pmid":"36037365","id":"PMC_36037365","title":"LAPTM5 mediates immature B cell apoptosis and B cell tolerance by regulating the WWP2-PTEN-AKT pathway.","date":"2022","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/36037365","citation_count":25,"is_preprint":false},{"pmid":"27058622","id":"PMC_27058622","title":"Down-regulation of LAPTM5 in human cancer cells.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27058622","citation_count":23,"is_preprint":false},{"pmid":"24638062","id":"PMC_24638062","title":"LAPTM5 promotes lysosomal degradation of intracellular CD3ζ but not of cell surface CD3ζ.","date":"2014","source":"Immunology and cell 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Population.","date":"2015","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/25998573","citation_count":7,"is_preprint":false},{"pmid":"22880058","id":"PMC_22880058","title":"Lysosomal-associated transmembrane protein 5 (LAPTM5) is a molecular partner of CD1e.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22880058","citation_count":6,"is_preprint":false},{"pmid":"37713124","id":"PMC_37713124","title":"c-Myc inhibits LAPTM5 expression in B-cell lymphomas.","date":"2023","source":"Annals of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/37713124","citation_count":5,"is_preprint":false},{"pmid":"36121636","id":"PMC_36121636","title":"Expression of RUNX2/LAPTM5 in the Induction of MC3T3-e1 Mineralization and Its Possible Relationship with Autophagy.","date":"2022","source":"Tissue engineering and regenerative medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36121636","citation_count":5,"is_preprint":false},{"pmid":"34658355","id":"PMC_34658355","title":"[Expression of RUNX2/LAPTM5 in MC3T3-E1 osteoblastic cells with induced mineralization].","date":"2021","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/34658355","citation_count":4,"is_preprint":false},{"pmid":"40280227","id":"PMC_40280227","title":"LAPTM5 confers cisplatin resistance in NSCLC by suppressing LAMP1 ubiquitination to stabilize lysosomal membranes and sustain autophagic flux.","date":"2025","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/40280227","citation_count":3,"is_preprint":false},{"pmid":"39753521","id":"PMC_39753521","title":"LAPTM5 Confers the Resistance to Venetoclax via Promoting the Autophagosome-Lysosome Fusion in Multiple Myeloma.","date":"2025","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39753521","citation_count":3,"is_preprint":false},{"pmid":"40755163","id":"PMC_40755163","title":"WDFY4 Promotes the Progression of Atherosclerosis by Regulating Ferroptosis Mediated by the LAPTM5/CDC42/mTOR/4EBP1/SLC7A11 Pathway.","date":"2025","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40755163","citation_count":2,"is_preprint":false},{"pmid":"40495222","id":"PMC_40495222","title":"LINC02888 promotes HGSOC progression and immune evasion via PPIB-mediated stabilization of LAPTM5 mRNA and inhibition of RIG-I-like receptor signaling.","date":"2025","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40495222","citation_count":2,"is_preprint":false},{"pmid":"38018874","id":"PMC_38018874","title":"ZKSCAN5 activates LAPTM5 expression by recruiting SETD7 to promote metastasis in pancreatic ductal adenocarcinoma.","date":"2023","source":"Histology and histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/38018874","citation_count":1,"is_preprint":false},{"pmid":"41124083","id":"PMC_41124083","title":"COL6A1, LAPTM5, and ZFAND2A as Crucial Biomolecules Driving Immunoregulation in Human Nucleus Pulposus Degeneration.","date":"2025","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/41124083","citation_count":1,"is_preprint":false},{"pmid":"41087666","id":"PMC_41087666","title":"LAPTM5 exacerbates STING-mediated inflammation induced by LL-37 through stabilizing STING in rosacea.","date":"2025","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/41087666","citation_count":1,"is_preprint":false},{"pmid":"41666511","id":"PMC_41666511","title":"Ginkgetin alleviates sepsis-induced acute lung injury by promoting autophagy via inhibiting ubiquitination of Laptm5 in macrophages.","date":"2026","source":"Phytomedicine : international journal of phytotherapy and phytopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/41666511","citation_count":0,"is_preprint":false},{"pmid":"41462255","id":"PMC_41462255","title":"LAPTM5 drives omental metastasis in high-grade serous ovarian cancer via TGF-β/Smad-mediated epithelial plasticity.","date":"2025","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41462255","citation_count":0,"is_preprint":false},{"pmid":"41969478","id":"PMC_41969478","title":"LAPTM5-dependent lipophagy enhances ferroptosis sensitivity in glioma cells.","date":"2026","source":"Translational cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/41969478","citation_count":0,"is_preprint":false},{"pmid":"41699322","id":"PMC_41699322","title":"LAPTM5 potentiates airway remodeling by regulating MAPKs-mediated airway smooth muscle cells' dysfunction.","date":"2026","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/41699322","citation_count":0,"is_preprint":false},{"pmid":"41912486","id":"PMC_41912486","title":"Targeting LAPTM5 enhances AML sensitivity to cytarabine through autophagy inhibition.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/41912486","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.29.630486","title":"H3K4-H3K9 Histone Methylation Patterns and Oncofetal Developmental Networks as Drivers of Cell Fate Decisions in Pediatric High-Grade Gliomas","date":"2024-12-30","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.29.630486","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":21613,"output_tokens":4774,"usd":0.068224},"stage2":{"model":"claude-opus-4-6","input_tokens":8288,"output_tokens":3662,"usd":0.199485},"total_usd":0.267709,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"LAPTM5 is a pentaspanning lysosomal transmembrane protein preferentially expressed in hematopoietic cells, localizing to lysosomes as determined by immunocytological and cell fractionation studies, and shows preliminary evidence of interaction with ubiquitin.\",\n      \"method\": \"Immunocytology, cell fractionation, cDNA cloning\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by fractionation; ubiquitin interaction preliminary/single method\",\n      \"pmids\": [\"8661146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"LAPTM5 trafficking from the Golgi to the lysosome requires its PY motifs (L/PPxY) binding to Nedd4 WW domains and its UIM motif binding ubiquitinated GGA3; Nedd4 binding to LAPTM5 (not LAPTM5 ubiquitination) is required for lysosomal targeting, and Nedd4 can also ubiquitinate GGA3.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, site-directed mutagenesis of PY and UIM motifs, subcellular localization imaging\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (mutagenesis, RNAi, coIP, localization), replicated across conditions\",\n      \"pmids\": [\"17116753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Accumulation of LAPTM5 protein induces non-apoptotic, caspase-independent lysosomal cell death characterized by lysosomal membrane permeabilization (LMP), disruption of autophagic flux, and accumulation of autophagic vacuoles and p62/SQSTM1 in neuroblastoma cells.\",\n      \"method\": \"In vitro overexpression/restoration of LAPTM5 expression, lysosomal membrane permeabilization assay, autophagy flux analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — defined cellular phenotype with multiple readouts in a single lab\",\n      \"pmids\": [\"19787053\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The HECT-type E3 ubiquitin ligase ITCH directly binds the PPxY motif of LAPTM5 via its WW domains and ubiquitinates LAPTM5 via its HECT domain, promoting LAPTM5 protein degradation; ITCH knockdown stabilizes LAPTM5 and enhances LAPTM5-mediated cell death.\",\n      \"method\": \"Co-immunoprecipitation, in vitro ubiquitination assay, siRNA knockdown, overexpression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct binding, in vitro ubiquitination, and functional consequence demonstrated\",\n      \"pmids\": [\"22009753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LAPTM5 is required for proinflammatory cytokine secretion in macrophages via TLR ligands; LAPTM5-deficient macrophages show reduced NF-κB and MAPK activation downstream of TNF receptor and pattern recognition receptors, reduced RIP1 ubiquitination, and upregulated A20 (a deubiquitinase of RIP1).\",\n      \"method\": \"LAPTM5 knockout mice, RNAi knockdown in RAW264.7 cells, NF-κB/MAPK signaling assays, cytokine secretion assays, ubiquitination assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO mice plus knockdown, multiple signaling readouts and mechanistic pathway placement\",\n      \"pmids\": [\"22733818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LAPTM5 is a molecular partner of CD1e; the two proteins co-localize in trans-Golgi and late endosomal compartments, and their association increases under bafilomycin treatment, though LAPTM5 does not control CD1e ubiquitination or generation of soluble lysosomal CD1e.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry identification, confocal co-localization\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, coIP and colocalization with partial functional follow-up\",\n      \"pmids\": [\"22880058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LAPTM5 promotes lysosomal translocation of newly synthesized intracellular CD3ζ (targeting it from the Golgi) but not cell-surface CD3ζ from the mature TCR complex; this pathway is independent of TCR signaling-triggered tyrosine phosphorylation of CD3ζ and operates via a distinct genetic pathway from SLAP/c-Cbl-mediated degradation.\",\n      \"method\": \"Subcellular localization kinetics, Golgi-localizing CD3ζ mutants, tyrosine-to-phenylalanine CD3ζ mutants, genetic epistasis (double knockdown/mutant analysis)\",\n      \"journal\": \"Immunology and cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple mutagenesis approaches, kinetic localization studies, genetic epistasis\",\n      \"pmids\": [\"24638062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Ectopic overexpression of LAPTM5 in HeLa cells localizes to lysosomes and induces apoptosis via Mcl-1 and Bid cleavage (by a lysosomal cathepsin-dependent pathway), Bak activation, mitochondrial membrane potential loss, and caspase-9/-8/-3 cascade; co-overexpression of Mcl-1 abrogates these events.\",\n      \"method\": \"GFP-LAPTM5 overexpression, flow cytometry, caspase activity assays, cathepsin inhibitor, mitochondrial membrane potential assay, western blotting\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal assays, rescue with Mcl-1, single lab\",\n      \"pmids\": [\"28464033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"LAPTM5 expression is transcriptionally activated by RUNX2, which directly binds the LAPTM5 promoter at position -1176 to -1171; LAPTM5 is involved in RANKL trafficking in osteoblastic cells, as LAPTM5 knockdown increases cytoplasmic and secreted RANKL and enhances osteoclast differentiation.\",\n      \"method\": \"Chromatin immunoprecipitation, dual-luciferase reporter assay, RUNX2 overexpression/silencing, RANKL trafficking assay, co-culture osteoclast differentiation assay\",\n      \"journal\": \"Molecular medicine reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus reporter assay confirms direct transcriptional activation; functional trafficking assay\",\n      \"pmids\": [\"31545469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LAPTM5 suppresses CD40-mediated NF-κB activation in glioblastoma; LAPTM5 knockdown unleashes CD40-driven NF-κB signaling, leading to enhanced invasiveness, clonogenicity, and temozolomide resistance that is overcome by NF-κB inhibition.\",\n      \"method\": \"RNAi knockdown in glioma cell lines, expression arrays, NF-κB inhibition rescue, in vitro and in vivo invasion/clonogenicity assays\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockdown with NF-κB inhibitor rescue and multiple functional readouts\",\n      \"pmids\": [\"32582531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HIV-1 Vpr counteracts LAPTM5 restriction by triggering LAPTM5 degradation via DCAF1; LAPTM5 inhibits HIV-1 particle infectivity by transporting HIV-1 envelope glycoproteins to lysosomes for degradation; LAPTM5 silencing phenocopies Vpr in macrophages, and LAPTM5 re-expression in CD4+ T cells reconstitutes Vpr-dependent HIV-1 infection enhancement.\",\n      \"method\": \"Viral infection assays, LAPTM5 knockdown/overexpression, Vpr mutant analysis, DCAF1 dependency assays, envelope glycoprotein trafficking to lysosomes\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal approaches including phenocopy, re-expression rescue, and mechanistic trafficking assay\",\n      \"pmids\": [\"34140527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"BCR stimulation upregulates LAPTM5, which triggers immature B cell apoptosis through two mechanisms: (1) promoting BCR internalization, reducing SYK and ERK phosphorylation; and (2) targeting the E3 ubiquitin ligase WWP2 for lysosomal degradation, causing PTEN accumulation, suppressed AKT phosphorylation, increased FOXO1/p27Kip1/BIM expression. LAPTM5 deficiency exacerbates autoantibody production in vivo.\",\n      \"method\": \"BCR stimulation assays, LAPTM5 knockout mice, co-immunoprecipitation, western blotting for signaling pathway components, flow cytometry for BCR internalization, in vivo autoantibody measurement\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — two mechanistic pathways defined by multiple orthogonal methods plus in vivo KO validation\",\n      \"pmids\": [\"36037365\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The lncRNA LCDR binds hnRNP K to stabilize LAPTM5 mRNA, maintaining lysosomal membrane integrity; knockdown of LCDR, hnRNP K, or LAPTM5 each promotes lysosomal membrane permeabilization and lysosomal cell death/apoptosis in lung cancer cells; LAPTM5 overexpression or cathepsin B inhibition partially rescues these effects.\",\n      \"method\": \"RNA pulldown, RIP-qPCR, siRNA knockdown, LAPTM5 overexpression rescue, lysosomal membrane permeabilization assay, in vivo xenograft\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, rescue experiments, and in vivo validation\",\n      \"pmids\": [\"35091468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"c-Myc trans-represses LAPTM5 transcription by binding two E-boxes in the LAPTM5 promoter; Myc also trans-activates miR-17-3p, which binds 11 sites in LAPTM5 3'UTR to suppress LAPTM5 protein synthesis, further dampening tumor-suppressive LAPTM5 in B-lymphomas.\",\n      \"method\": \"Promoter binding assays (E-box mutagenesis), miRNA target site analysis, reporter assays, functional growth assays\",\n      \"journal\": \"Annals of hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct promoter binding and miRNA target site demonstrated; single lab\",\n      \"pmids\": [\"37713124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LAPTM5 competes with LAMP1 for binding to the E3 ubiquitin ligase WWP2, thereby inhibiting LAMP1 ubiquitination and degradation to preserve lysosomal membrane stability and sustain autophagic flux, conferring cisplatin resistance in NSCLC; LAPTM5 knockdown increases lysosomal membrane permeability, releases cathepsin D, elevates ROS, and accelerates cell death.\",\n      \"method\": \"Co-immunoprecipitation, LAPTM5 knockdown, cathepsin D release assay, ROS measurement, autophagic flux assay, western blotting\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — competitive binding mechanism supported by coIP and functional assays; single lab\",\n      \"pmids\": [\"40280227\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LAPTM5 associates with STING, represses its K48- and K63-linked polyubiquitination, preventing both proteasomal and lysosomal degradation of STING, thereby maintaining STING protein stability; LAPTM5 knockdown reduces STING protein levels and downstream inflammatory signaling in macrophages.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays (K48/K63 linkage-specific), LAPTM5 knockdown, STING signaling assays\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct interaction and mechanistic ubiquitination suppression demonstrated; single lab\",\n      \"pmids\": [\"41087666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Ginkgetin inhibits K48-linked ubiquitination of LAPTM5 at residues K86 and K122 by targeting Ube3c (ubiquitin-protein ligase E3C), thereby increasing LAPTM5 protein levels, promoting autophagosome-lysosome fusion, and enabling autophagic degradation of TBK1 to suppress inflammatory signaling in macrophages during sepsis-induced acute lung injury.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis (K86/K122), biotin pulldown with mass spectrometry, DARTS, molecular docking, proteomics, autophagy flux assays\",\n      \"journal\": \"Phytomedicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ubiquitination site mapping by mutagenesis, direct target identification by pulldown/MS, functional assays in vitro and in vivo\",\n      \"pmids\": [\"41666511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In AML, LAPTM5 promotes LAMP1 and LAMP2 transcription, supporting lysosomal biogenesis and autophagolysosome formation to sustain autophagic flux and reduce cytarabine-induced apoptosis; LAPTM5 knockdown impairs autophagolysosome formation and lysosomal biogenesis, sensitizing resistant AML cells to cytarabine in vitro and in vivo.\",\n      \"method\": \"scRNA-seq data analysis, LAPTM5 knockdown, autophagic flux assay, LAMP1/LAMP2 expression analysis, in vivo tumor model\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — knockdown with defined mechanistic pathway and in vivo validation; single lab\",\n      \"pmids\": [\"41912486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"WDFY4 interacts with LAPTM5 (validated by co-immunoprecipitation and immunofluorescence co-localization); WDFY4 interference inhibits LAPTM5 expression and activates the downstream CDC42/mTOR/4EBP1/SLC7A11 pathway, reducing ferroptosis; LAPTM5 overexpression rescues ferroptosis suppression caused by WDFY4 knockdown.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, WDFY4/LAPTM5 knockdown/overexpression, pathway analysis (CDC42/mTOR/4EBP1/SLC7A11), in vivo atherosclerosis model\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct interaction validated, epistasis by rescue experiment, in vivo model\",\n      \"pmids\": [\"40755163\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LAPTM5 is a pentaspanning lysosomal transmembrane protein that uses its PY motifs to bind Nedd4/ITCH ubiquitin ligases and its UIM to recruit ubiquitinated GGA3, enabling Golgi-to-lysosome cargo sorting (including CD3ζ and BCR/TCR components) independent of its own ubiquitination; it maintains lysosomal membrane integrity by competing with LAMP1 for WWP2-mediated ubiquitination and by stabilizing STING against ubiquitin-dependent degradation; in immune cells it acts as a context-dependent regulator—promoting inflammatory NF-κB/MAPK signaling in macrophages via RIP1 ubiquitination, triggering immature B cell apoptosis through WWP2/PTEN/AKT/FOXO1 pathway and BCR internalization, and serving as a restriction factor for HIV-1 by routing envelope glycoproteins to lysosomal degradation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LAPTM5 is a pentaspanning lysosomal transmembrane protein, preferentially expressed in hematopoietic cells, that functions as a central regulator of lysosomal cargo sorting, lysosomal membrane integrity, and immune cell signaling. Its Golgi-to-lysosome trafficking depends on PY motifs that recruit Nedd4-family HECT E3 ubiquitin ligases (Nedd4, ITCH) and a UIM that binds ubiquitinated GGA3, enabling it to route diverse cargoes—including newly synthesized CD3ζ, BCR components, HIV-1 envelope glycoproteins, and RANKL—to lysosomes for degradation [PMID:17116753, PMID:24638062, PMID:34140527, PMID:31545469]. LAPTM5 preserves lysosomal membrane stability by competing with LAMP1 for WWP2-mediated ubiquitination and by promoting LAMP1/LAMP2 expression and autophagolysosome formation, and it stabilizes STING by suppressing its K48/K63-linked polyubiquitination [PMID:40280227, PMID:41912486, PMID:41087666]. In immune cells, LAPTM5 has context-dependent roles: it promotes NF-κB/MAPK inflammatory signaling in macrophages through RIP1 ubiquitination, enforces negative selection of autoreactive immature B cells by internalizing BCR and degrading WWP2 to activate the PTEN/AKT/FOXO1 apoptotic axis, and restricts HIV-1 infectivity by targeting viral envelope glycoproteins for lysosomal degradation—a function counteracted by HIV-1 Vpr via DCAF1-dependent LAPTM5 destruction [PMID:22733818, PMID:36037365, PMID:34140527].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Establishing the identity and subcellular home of LAPTM5 answered where in the cell this hematopoietic-restricted protein operates, placing it at lysosomes with preliminary ubiquitin association.\",\n      \"evidence\": \"cDNA cloning, immunocytology, and cell fractionation in hematopoietic cells\",\n      \"pmids\": [\"8661146\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitin interaction was preliminary and lacked biochemical validation\", \"No functional role established\", \"Topology and membrane-spanning architecture not experimentally resolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defining the molecular logic of LAPTM5 trafficking revealed that PY-motif/Nedd4 binding and UIM/GGA3 interaction constitute two separable sorting signals for Golgi-to-lysosome transport, and that Nedd4 binding—not LAPTM5 ubiquitination—is the critical trafficking determinant.\",\n      \"evidence\": \"Mutagenesis of PY and UIM motifs, Nedd4 RNAi, co-immunoprecipitation, subcellular localization imaging\",\n      \"pmids\": [\"17116753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other Nedd4-family ligases substitute for Nedd4 in vivo\", \"Structural basis of PY–WW domain recognition for LAPTM5 not determined\", \"Cargo repertoire beyond LAPTM5 itself not yet identified\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrating that LAPTM5 accumulation induces lysosomal membrane permeabilization and non-apoptotic cell death linked it to a lysosomal cell death pathway and hinted at a tumor-suppressive function.\",\n      \"evidence\": \"LAPTM5 overexpression/restoration in neuroblastoma cells, LMP assays, autophagy flux analysis\",\n      \"pmids\": [\"19787053\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which LAPTM5 triggers LMP was undefined\", \"Physiological relevance in endogenous expression contexts unclear\", \"Relationship between LAPTM5 levels and lysosomal membrane composition not explored\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identifying ITCH as a second HECT E3 that ubiquitinates and degrades LAPTM5 established a feedback mechanism controlling LAPTM5 protein levels and linked LAPTM5 turnover to cell death regulation.\",\n      \"evidence\": \"Co-immunoprecipitation, in vitro ubiquitination assay, siRNA knockdown of ITCH\",\n      \"pmids\": [\"22009753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of ITCH vs Nedd4 to LAPTM5 turnover in different cell types unresolved\", \"Whether ITCH-mediated degradation is proteasomal or lysosomal not clarified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Two studies expanded LAPTM5 function beyond trafficking: in macrophages, LAPTM5 promotes inflammatory NF-κB/MAPK signaling by sustaining RIP1 ubiquitination downstream of TLRs and TNF receptor; separately, LAPTM5 was identified as a molecular partner of CD1e in Golgi/endosomal compartments.\",\n      \"evidence\": \"LAPTM5 knockout mice and RAW264.7 knockdown with cytokine/signaling assays; co-IP/MS identification and confocal co-localization of CD1e–LAPTM5\",\n      \"pmids\": [\"22733818\", \"22880058\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct mechanism by which LAPTM5 sustains RIP1 ubiquitination (e.g., does it sequester A20?) not biochemically resolved\", \"Functional consequence of CD1e–LAPTM5 interaction on antigen presentation unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showing that LAPTM5 selectively targets newly synthesized intracellular CD3ζ (but not surface TCR-associated CD3ζ) for lysosomal degradation identified a specific cargo and distinguished this pathway from SLAP/c-Cbl-mediated TCR downregulation.\",\n      \"evidence\": \"Golgi-localizing CD3ζ mutants, tyrosine-to-phenylalanine mutants, genetic epistasis analysis\",\n      \"pmids\": [\"24638062\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether LAPTM5 directly binds CD3ζ or acts through an adaptor not determined\", \"Physiological impact on T cell development or activation thresholds not tested in vivo\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrating that RUNX2 directly transactivates the LAPTM5 promoter and that LAPTM5 controls RANKL trafficking in osteoblasts extended its function beyond hematopoietic cells to bone biology.\",\n      \"evidence\": \"Chromatin immunoprecipitation, dual-luciferase reporter, RANKL trafficking and osteoclast differentiation assays\",\n      \"pmids\": [\"31545469\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo bone phenotype of LAPTM5 deficiency not characterized\", \"Whether LAPTM5 routes RANKL via the same PY/UIM-dependent mechanism as other cargoes not tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identifying LAPTM5 as a restriction factor for HIV-1—routing envelope glycoproteins to lysosomes for degradation—and showing that HIV-1 Vpr counteracts it via DCAF1-dependent LAPTM5 destruction revealed a virus–host arms race centered on lysosomal sorting.\",\n      \"evidence\": \"Viral infection assays with Vpr mutants, LAPTM5 knockdown/re-expression, DCAF1 dependency, envelope trafficking to lysosomes in macrophages and CD4+ T cells\",\n      \"pmids\": [\"34140527\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether LAPTM5 restricts other enveloped viruses not explored\", \"Structural basis of Vpr–DCAF1–LAPTM5 ternary complex not resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Two parallel advances established LAPTM5's dual role in B cell tolerance and lysosomal membrane integrity: BCR-stimulated LAPTM5 promotes immature B cell apoptosis by internalizing BCR and degrading WWP2 (activating PTEN/AKT/FOXO1), while the lncRNA LCDR/hnRNP K axis stabilizes LAPTM5 mRNA to maintain lysosomal membrane integrity in cancer cells.\",\n      \"evidence\": \"LAPTM5 KO mice with autoantibody assays, BCR internalization/signaling pathway dissection; RNA pulldown, RIP-qPCR, LMP assays, in vivo xenograft rescue\",\n      \"pmids\": [\"36037365\", \"35091468\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether LAPTM5-mediated WWP2 degradation requires its PY motifs not tested\", \"How LAPTM5 physically maintains lysosomal membrane stability at the structural level remains unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Multiple studies refined LAPTM5's lysosomal-protective and signaling roles: LAPTM5 competes with LAMP1 for WWP2 binding to prevent LAMP1 degradation and preserve autophagic flux; LAPTM5 stabilizes STING by suppressing K48/K63-linked polyubiquitination; and WDFY4 interaction with LAPTM5 regulates ferroptosis through CDC42/mTOR signaling.\",\n      \"evidence\": \"Co-IP competition assays, linkage-specific ubiquitination assays, LAPTM5/WDFY4 epistasis with rescue, in vivo atherosclerosis and NSCLC models\",\n      \"pmids\": [\"40280227\", \"41087666\", \"40755163\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Competition model for LAMP1/LAPTM5/WWP2 awaits reconstitution with purified components\", \"Mechanism by which LAPTM5 suppresses STING ubiquitination (direct shielding vs. recruiting a DUB) unknown\", \"WDFY4–LAPTM5 interaction stoichiometry and structural basis not defined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Mapping K48-linked ubiquitination of LAPTM5 at K86 and K122 by Ube3c, and showing that stabilization of LAPTM5 promotes autophagosome–lysosome fusion and autophagic TBK1 degradation, established a druggable axis (targeted by ginkgetin) for controlling inflammation; separately, LAPTM5 was shown to promote LAMP1/LAMP2 transcription and lysosomal biogenesis to maintain autophagic flux and drug resistance in AML.\",\n      \"evidence\": \"Site-directed mutagenesis of K86/K122, biotin pulldown/MS target identification (Ube3c), autophagy flux assays in sepsis model; scRNA-seq, LAPTM5 knockdown, LAMP1/LAMP2 expression analysis, in vivo AML model\",\n      \"pmids\": [\"41666511\", \"41912486\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Ube3c is the primary E3 controlling LAPTM5 turnover in all cell types or context-specific\", \"Mechanism by which LAPTM5 promotes LAMP1/LAMP2 transcription is undefined\", \"In vivo validation of ginkgetin efficacy via LAPTM5-specific mechanisms needs genetic confirmation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis of LAPTM5's pentaspanning architecture, how it physically stabilizes lysosomal membranes, and the complete cargo repertoire it sorts remain open questions; whether its opposing roles in inflammation (promoting NF-κB in macrophages vs. suppressing it in glioblastoma) reflect cell-type-specific interactors or distinct signaling complexes is unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of LAPTM5\", \"No systematic cargo identification (e.g., proximity labeling)\", \"Cell-type-specific interactome not mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 6, 10, 14]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 11, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [0, 1, 2, 6, 7, 10, 12, 14]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [1, 5, 6]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [2, 12, 14, 16, 17]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [4, 6, 10, 11]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [2, 7, 11, 12]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 6, 10]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 15, 16]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 9, 11]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"NEDD4\",\n      \"ITCH\",\n      \"GGA3\",\n      \"WWP2\",\n      \"STING1\",\n      \"WDFY4\",\n      \"UBE3C\",\n      \"CD1E\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}