{"gene":"ARL8B","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2006,"finding":"ARL8B (Arl8b) localizes to lysosomal membranes and a GTP-restricted (constitutively active) mutant of Arl8b redistributes lysosomes to the cell periphery and into membrane projections, indicating Arl8b controls lysosomal spatial distribution via GTP-dependent activity.","method":"Confocal immunofluorescence microscopy, GTP-restricted mutant expression, co-localization with lysosomal markers","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct localization experiment with functional consequence (lysosome redistribution), single lab, single method","pmids":["16650381"],"is_preprint":false},{"year":2009,"finding":"The human NatC complex (hNatC), containing catalytic subunit hMak3, acetylates Met-Leu protein N-termini in vitro; knockdown of hMAK3 alters subcellular localization of ARL8B, supporting ARL8B as an in vivo substrate of hNatC-mediated N-terminal acetylation.","method":"In vitro acetyltransferase assay, siRNA knockdown, subcellular localization imaging","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro enzymatic assay plus cellular knockdown showing localization change, single lab, two orthogonal methods","pmids":["19398576"],"is_preprint":false},{"year":2011,"finding":"Arl8b is required for cargo delivery to lysosomes; HOPS complex members (homotypic fusion and vacuole protein sorting complex) are effectors of Arl8b and depend on Arl8b for their recruitment to lysosomes, establishing an Arl8b-HOPS axis that directs lysosomal trafficking.","method":"shRNA library screen, RNAi knockdown, immunofluorescence co-localization, phagosome-lysosome fusion assay, CD1 antigen presentation assay","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal functional assays (trafficking, fusion, antigen presentation) plus effector identification, replicated across cell types","pmids":["21802320"],"is_preprint":false},{"year":2011,"finding":"Salmonella exploits Arl8b on Salmonella-containing vacuoles (SCVs) to recruit kinesin-1, driving tubulated endosome (SIF) formation, SCV migration to the cell periphery, and cell-to-cell bacterial transfer.","method":"Bacterial infection model, RNAi knockdown, immunofluorescence for kinesin-1 recruitment, LAMP1-tubule formation assay","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined cellular phenotypes and kinesin-1 recruitment readout, single lab","pmids":["21824248"],"is_preprint":false},{"year":2013,"finding":"Arl8b is required for NK cell cytotoxicity by driving polarization of lytic granules and MTOCs toward the immune synapse; kinesin-1 heavy chain KIF5B was identified as an Arl8b interaction partner via GST pull-down, and the Arl8b–SKIP–kinesin-1 tripartite complex mediates anterograde granule movement.","method":"GST pull-down, shRNA knockdown, lytic granule polarization assay, cytotoxicity assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — direct biochemical interaction (GST pull-down) combined with functional loss-of-function showing specific NK cytotoxicity phenotype, multiple orthogonal methods","pmids":["24088571"],"is_preprint":false},{"year":2015,"finding":"Arl8b, but not Rab7, is essential for membrane localization of hVps41, the HOPS complex subunit; Arl8b-dependent lysosomal localization of hVps41 is required for EGFR endocytic degradation, as an Arl8b-binding-defective mutant of hVps41 fails to rescue EGFR degradation. Additionally, Arl8b effector SKIP interacts with and recruits HOPS subunits to peripheral lysosomes.","method":"RNAi depletion, rescue with Arl8b-binding-defective mutant, EGFR degradation assay, co-immunoprecipitation","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — mutant rescue experiment plus RNAi with functional readout and co-IP, multiple orthogonal methods in single lab","pmids":["25908847"],"is_preprint":false},{"year":2015,"finding":"Arl8b localizes to MHC class II compartments in dendritic cells and regulates formation of MHC II–peptide complexes and their delivery to the plasma membrane for T cell activation.","method":"RNAi silencing, immunofluorescence localization, MHC II–peptide complex formation assay, T cell activation assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined immunological functional readouts, direct localization, single lab","pmids":["25637027"],"is_preprint":false},{"year":2016,"finding":"Arl8b regulates anterograde lysosome trafficking to the cell periphery in response to HGF, EGF, and acidic extracellular pH; depletion of Arl8b impairs invasive growth and proteolytic ECM degradation in 3D prostate cancer models and abolishes xenograft formation in mice.","method":"RNAi knockdown, 3D invasion assay, lysosome positioning assay, xenograft mouse model","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with multiple phenotypic readouts in vitro and in vivo, single lab","pmids":["27105540"],"is_preprint":false},{"year":2016,"finding":"RNF167, a RING-domain E3 ubiquitin ligase, ubiquitinates Arl8B at lysine K141, reducing Arl8B protein levels; RNF167 overexpression/knockdown correspondingly alters Arl8b-dependent lysosome positioning and endocytic trafficking, and an ubiquitination-defective Arl8B K141R mutant counteracts RNF167 effects.","method":"Proximity-dependent biotin labeling (BioID), ubiquitination assay, site-directed mutagenesis (K141R), lysosome positioning assay, endocytic trafficking assay","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct biochemical ubiquitination assay, mutagenesis identifying site, functional rescue with mutant, multiple orthogonal methods single lab","pmids":["27808481"],"is_preprint":false},{"year":2017,"finding":"The C-terminal domain of lyspersin (a BORC subunit) is essential and sufficient for BORC-dependent recruitment of Arl8b to lysosomes; LAMTOR negatively regulates this process by associating with BORC, and EGF stimulation reduces LAMTOR/BORC association to promote Arl8b-dependent centrifugal lysosomal transport.","method":"Domain deletion analysis, co-immunoprecipitation, lysosome positioning assay, EGF stimulation","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — domain mapping with functional readout, co-IP, upstream regulatory mechanism identified, single lab with multiple orthogonal approaches","pmids":["28993467"],"is_preprint":false},{"year":2017,"finding":"Arl8b is required for lysosomal degradation of maternal proteins in the visceral yolk sac endoderm; Arl8b gene-trap and conditional knockout mice show defective endocytic trafficking to lysosomes, accumulation of maternal proteins (albumin, IgG) in late endocytic organelles, reduced free amino acids in embryos, and decreased embryo body size.","method":"Gene-trap mouse model, conditional knockout (Transthyretin-Cre), immunofluorescence, free amino acid measurement","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic knockout with defined molecular and developmental phenotypes, two independent genetic models","pmids":["28827407"],"is_preprint":false},{"year":2018,"finding":"Arl8b is required for lysosomal exocytosis-mediated plasma membrane repair; Arl8b-depleted cells fail to repair plasma membrane damage induced by M. tuberculosis, causing necrosis instead of apoptosis in macrophages infected with avirulent H37Ra.","method":"RNAi knockdown, plasma membrane repair assay, lysosomal exocytosis assay, macrophage infection model","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with mechanistically defined cellular phenotype (exocytosis, cell death type), single lab, multiple readouts","pmids":["29592961"],"is_preprint":false},{"year":2019,"finding":"HCV infection increases Arl8b expression ~3-fold and redistributes it to a peripheral pattern that fails to co-localize with LC3-positive autophagosomes; knockdown of Arl8b in HCV-infected cells restores autophagosome-lysosome fusion and autophagic flux, demonstrating that HCV suppresses autophagic flux by upregulating and repositioning Arl8b.","method":"RNAi knockdown, tandem RFP-GFP-LC3 autophagic flux assay, in vitro vesicle fusion assay, immunofluorescence","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function restores flux, in vitro fusion assay distinguishes trafficking vs. fusion defect, single lab","pmids":["31383738"],"is_preprint":false},{"year":2019,"finding":"Loss of Arl8b in mice disrupts dorsal neural tube development, including ectopic Sox1 expression in the roof plate and elevated BMP receptor IA and phospho-Smad 1/5/8 signaling in the neural fold, suggesting Arl8b regulates BMP signaling during neural tube development.","method":"Gene-trap knockout mice, immunohistochemistry, in situ hybridization, western blot for BMP pathway components","journal":"Genes to cells","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic KO with defined molecular phenotype, but pathway placement (BMP signaling) is correlative rather than directly tested, single lab","pmids":["31038803"],"is_preprint":false},{"year":2020,"finding":"Arl8b controls density and position of interstitial axon branches in retinal ganglion cells by spatially controlling the location and density of lysosomes and autophagosomes along the axon shaft; Arl8b downregulation reduces branch density and shifts branches proximally, while overexpression increases density and positions branches more distally.","method":"shRNA knockdown, overexpression, immunofluorescence, in vivo conditional knockout (atg7), rapamycin treatment","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function with quantitative phenotypic readouts in vitro and in vivo, single lab","pmids":["32917789"],"is_preprint":false},{"year":2020,"finding":"Arl8b binding to its effector SKIP is increased after radiation through regulation of BORC subunits; Arl8b and BORC-mediated lysosomal exocytosis drives invasiveness of radiation-surviving cancer cells, and in vivo Arl8b ablation decreases IR-induced invasive tumor growth and metastasis.","method":"Co-immunoprecipitation, RNAi knockdown, lysosomal exocytosis assay, in vivo mouse tumor model","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP showing increased Arl8b-SKIP binding post-radiation, loss-of-function in vivo with defined metastasis readout, single lab","pmids":["33110168"],"is_preprint":false},{"year":2022,"finding":"RUFY3 is an Arl8b effector that regulates retrograde lysosomal transport; RUFY3 interacts with the JIP4-dynein-dynactin complex and facilitates Arl8b association with the retrograde motor complex. RUFY3 knockdown disrupts Arl8b-positive endosome positioning, reduces Arl8b colocalization with Rab7-marked compartments, and reduces lysosome size (rescued by PIKFYVE inhibition).","method":"Co-immunoprecipitation, RNAi knockdown, lysosome positioning assay, co-localization imaging, PIKFYVE inhibitor rescue","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, loss-of-function with multiple defined phenotypes and rescue experiment, single lab with multiple orthogonal methods","pmids":["35314681"],"is_preprint":false},{"year":2022,"finding":"Arl8b binds RUFY1 and determines RUFY1 endosomal localization by regulating its interaction with Rab14; RUFY1 mediates endosome-to-TGN retrieval of CI-M6PR via the dynein-dynactin complex, and RUFY1 depletion delays CI-M6PR retrieval and impairs lysosomal cargo (cathepsin) delivery.","method":"Co-immunoprecipitation, RNAi depletion, CI-M6PR trafficking assay, dynein interaction assay, electron microscopy","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, loss-of-function with defined cargo trafficking readout and rescue, multiple orthogonal methods single lab","pmids":["36282215"],"is_preprint":false},{"year":2022,"finding":"The Salmonella effector SifA mimics the Arl8a/Arl8b-SKIP pathway by recruiting kinesin-1 and kinesin-3 (KIF1Bβ) to Salmonella vacuoles; in the non-infectious context, SKIP is essential for kinesin-3 recruitment to a fraction of lysosomes downstream of Arl8b.","method":"Bacterial infection model, co-immunoprecipitation, kinesin recruitment assay, vacuole stability assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP and functional assays showing kinesin-3 recruitment via SKIP downstream of Arl8b, single lab","pmids":["34878110"],"is_preprint":false},{"year":2023,"finding":"ARL8B-GDP localizes to lipid droplets (LDs) via an exposed N-terminal amphipathic helix induced by GDP binding; ARL8B-GTP predominantly localizes to lysosomes. By associating with both organelles, ARL8B mediates LD-lysosome contacts and lipid transfer, serving as the major lipolytic pathway in human macrophages.","method":"Fluorescence microscopy, GDP/GTP conformational analysis, LD-lysosome contact site assay, lipid transfer assay, macrophage functional assay","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — conformational mechanism identified, organelle contact and lipid transfer directly measured, functional validation in macrophages, multiple orthogonal methods","pmids":["37777960"],"is_preprint":false},{"year":2024,"finding":"DENND6A is an Arl8b effector; Arl8b recruits DENND6A to peripheral lysosomes where DENND6A acts as a GEF activating Rab34, which then recruits a RILP/dynein complex to initiate lysosomal retrograde transport, regulating nutrient-dependent juxtanuclear lysosome repositioning and autophagic flux.","method":"GEF activity assay (cell-based), co-immunoprecipitation, loss-of-function, lysosome positioning assay, autophagic flux assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — GEF activity demonstrated, effector cascade mapped (Arl8b→DENND6A→Rab34→RILP/dynein) with functional consequences, multiple orthogonal methods single lab","pmids":["38296963"],"is_preprint":false},{"year":2024,"finding":"ARL8B directly interacts with RAB2A (shown by mass spectrometry and co-IP) and increases GTP-bound RAB2A levels, activating the MAPK/ERK signaling pathway in hepatocellular carcinoma cells.","method":"Mass spectrometry, co-immunoprecipitation, GTP-RAB2A pull-down, ERK phosphorylation assay","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — co-IP and signaling assay, single lab, mechanistic link between ARL8B and ERK via RAB2A not fully validated","pmids":["39413890"],"is_preprint":false},{"year":2025,"finding":"VPS41 binds Arl8b via its WD40 domain; Arl8b is present on TGN-derived LAMP carriers and enables their recruitment by VPS41, expanding VPS41-Arl8b interactions beyond endosome-lysosome fusion to include biosynthetic LAMP carrier trafficking.","method":"Mitochondria mis-targeting (ectopic VPS41), RUSH system for newly synthesized LAMP tracking, electron microscopy, co-IP/binding assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — RUSH pulse-chase, ectopic localization assay, and binding domain identified with EM validation; multiple orthogonal methods single lab","pmids":["39907656"],"is_preprint":false},{"year":2025,"finding":"ARL8B interacts with RAB5A (identified by co-IP and GST pull-down); ARL8B promotes RAB5A-mediated ITGB1 endosomal recycling and prevents ITGB1 lysosomal degradation, thereby maintaining ITGB1 levels and FAK signaling to support osteocyte dendritic process formation.","method":"Co-immunoprecipitation, GST pull-down, lysosome immunoprecipitation, cell surface biotinylation, ITGB1 trafficking assay","journal":"Stem cell research & therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — reciprocal pull-down showing ARL8B-RAB5A interaction with functional cargo trafficking readout, single lab","pmids":["41163020"],"is_preprint":false},{"year":2026,"finding":"Arl8b localizes to post-endocytic LAMP1-containing vesicles and recruits the Rab11a GAP TBC1D9B to LAMP1-positive membranes, inactivating the Rab11a recycling pathway; without Arl8b, LAMP1 undergoes Rab11a-dependent recycling to the plasma membrane instead of lysosomal delivery. TBC1D9B knockdown also impairs CI-M6PR retrieval from Rab11a/Rab14 endosomes to the TGN, impairing cathepsin delivery.","method":"RUSH assay, RNAi depletion, Rab11a GAP recruitment assay, LAMP1 trafficking assay, CI-M6PR retrieval assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — RUSH pulse-chase, loss-of-function with defined cargo trafficking phenotype, GAP recruitment mechanism identified, multiple orthogonal methods single lab","pmids":["42166252"],"is_preprint":false},{"year":2026,"finding":"RNF13 binds Arl8B via residues Glu22 and Phe55 of Arl8B (and Leu244 of RNF13) with modest preference for GDP-bound Arl8B; disrupting this interaction redistributes lysosomes to the cell periphery and selectively delays EGFR trafficking toward lysosomal degradation.","method":"Predictive structural modeling, co-immunoprecipitation, site-directed mutagenesis, lysosome positioning assay, EGFR trafficking assay","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 2-3 / Weak — co-IP with residue-level mutagenesis, functional readout, but structural model is predictive not experimental, single lab","pmids":["42206902"],"is_preprint":false},{"year":2025,"finding":"RNF13 mediates ubiquitin-dependent degradation of ARL8B; RNF13 activity is regulated by intracellular pH and Ca2+-bound ALG-2 (apoptosis-linked gene 2). Elevated pH_i deprotonates RNF13 at His332, enabling ALG-2 interaction and RNF13 activation, which reduces ARL8B levels and inhibits anterograde lysosomal transport; alkaline extracellular pH elevates lysosomal Ca2+ via TRPML3, further activating RNF13.","method":"pH manipulation, Ca2+ signaling assay, ubiquitination assay, lysosome positioning assay, RNF13 mutagenesis (His332), co-immunoprecipitation","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-specific mutagenesis identifying His332, multiple signaling inputs tested, functional readout, but preprint not yet peer-reviewed","pmids":[],"is_preprint":true}],"current_model":"ARL8B is a lysosome-resident Arf-like GTPase that, when GTP-bound, localizes to lysosomes and drives their anterograde (centrifugal) movement by recruiting the SKIP–kinesin-1 complex and, via DENND6A-Rab34-RILP, also coordinates retrograde transport through dynein; it recruits the HOPS tethering complex (via hVps41) to lysosomes to enable late endosome–lysosome fusion, LAMP carrier trafficking, and lysosomal cargo degradation, while in the GDP-bound state it additionally localizes to lipid droplets to mediate LD–lysosome contacts and lipid transfer; its activity is tuned by upstream regulators including BORC/lyspersin (which loads Arl8b onto lysosomes), LAMTOR (which antagonizes BORC), and post-translational modifications including NatC-mediated N-terminal acetylation and RNF167/RNF13-mediated ubiquitination at K141 that target it for degradation, collectively positioning Arl8b as a master organizer of lysosomal identity, positioning, fusion, biogenesis, and immune function."},"narrative":{"mechanistic_narrative":"ARL8B is a lysosome-resident Arf-like GTPase that functions as a master organizer of lysosomal positioning, fusion, biogenesis, and immune function [PMID:16650381, PMID:21802320]. In its GTP-bound state it localizes to lysosomal membranes, and constitutively active mutants redistribute lysosomes to the cell periphery, establishing GTP-dependent control of lysosomal spatial distribution [PMID:16650381]. ARL8B drives anterograde, centrifugal lysosome transport by assembling a tripartite ARL8B–SKIP–kinesin-1 (KIF5B) complex, with SKIP also recruiting kinesin-3 (KIF1Bβ) to a subset of lysosomes [PMID:24088571, PMID:34878110]. Opposing retrograde transport is coordinated through effectors RUFY3, which couples ARL8B to the JIP4–dynein–dynactin complex, and DENND6A, a GEF that activates Rab34 to recruit a RILP/dynein complex [PMID:35314681, PMID:38296963]. ARL8B also recruits the HOPS tethering complex to lysosomes—it is essential for membrane localization of the HOPS subunit hVps41/VPS41 (via its WD40 domain), enabling late endosome–lysosome fusion, endocytic cargo degradation including EGFR, and recruitment of TGN-derived biosynthetic LAMP carriers [PMID:21802320, PMID:25908847, PMID:39907656]. Beyond degradative trafficking, ARL8B governs lysosomal cargo delivery by controlling endosomal recycling machinery: it recruits the Rab11a GAP TBC1D9B and determines the localization of RUFY1 and the retrieval of CI-M6PR, biasing cargo toward lysosomal delivery rather than plasma-membrane recycling [PMID:36282215, PMID:42166252]. In the GDP-bound conformation an exposed N-terminal amphipathic helix targets ARL8B to lipid droplets, where it mediates LD–lysosome contacts and lipid transfer as a major lipolytic route in macrophages [PMID:37777960]. These activities underlie diverse cellular and immune processes including HOPS-dependent antigen presentation, NK-cell lytic granule polarization, lysosomal exocytosis for plasma-membrane repair, embryonic maternal-protein degradation, and axon-branch positioning [PMID:21802320, PMID:24088571, PMID:28827407, PMID:29592961, PMID:32917789]. ARL8B activity is tuned by upstream BORC/lyspersin, which loads ARL8B onto lysosomes and is antagonized by LAMTOR, and by post-translational modifications: NatC-mediated N-terminal acetylation and RNF167/RNF13-mediated ubiquitination at K141 that target it for degradation [PMID:19398576, PMID:27808481, PMID:28993467, PMID:42206902].","teleology":[{"year":2006,"claim":"Established that ARL8B is a lysosomal GTPase whose activity dictates organelle positioning, answering whether it has a defined subcellular role.","evidence":"Confocal immunofluorescence with a GTP-restricted mutant showing lysosome redistribution to the periphery","pmids":["16650381"],"confidence":"Medium","gaps":["No molecular effectors of the positioning identified","GTP-loading mechanism not addressed"]},{"year":2009,"claim":"Showed ARL8B is regulated post-translationally, identifying NatC-mediated N-terminal acetylation as a determinant of its localization.","evidence":"In vitro acetyltransferase assay plus hMAK3 knockdown with localization imaging","pmids":["19398576"],"confidence":"Medium","gaps":["Functional consequence of mis-localization not quantified","Direct acetylation of ARL8B not shown in cells"]},{"year":2011,"claim":"Defined the ARL8B–HOPS axis and ARL8B's requirement for lysosomal cargo delivery, linking the GTPase to membrane fusion machinery and immune trafficking.","evidence":"shRNA screen, RNAi, phagosome-lysosome fusion and CD1 antigen presentation assays","pmids":["21802320"],"confidence":"High","gaps":["Which HOPS subunit directly binds ARL8B not resolved here","Anterograde motor link not yet established"]},{"year":2011,"claim":"Revealed ARL8B is hijacked by pathogens to drive vacuole motility, demonstrating its kinesin-recruitment function in an infection context.","evidence":"Salmonella infection model with RNAi and kinesin-1 recruitment imaging","pmids":["21824248"],"confidence":"Medium","gaps":["Direct ARL8B-kinesin interaction not biochemically shown","Adaptor between ARL8B and kinesin-1 not identified"]},{"year":2013,"claim":"Identified the ARL8B–SKIP–kinesin-1 (KIF5B) tripartite complex and its role in NK-cell cytotoxicity, providing the biochemical basis for anterograde movement.","evidence":"GST pull-down for KIF5B interaction plus shRNA, granule polarization and cytotoxicity assays","pmids":["24088571"],"confidence":"High","gaps":["Stoichiometry/structure of the tripartite complex unresolved","Regulation of complex assembly not defined"]},{"year":2015,"claim":"Established that ARL8B is required for membrane localization of HOPS subunit hVps41 and downstream EGFR degradation, ordering the ARL8B–SKIP–HOPS hierarchy.","evidence":"RNAi, Arl8b-binding-defective hVps41 rescue, EGFR degradation assay, co-IP","pmids":["25908847"],"confidence":"High","gaps":["Direct ARL8B-hVps41 binding interface not mapped here","Rab7-independence mechanism not fully explained"]},{"year":2015,"claim":"Extended ARL8B function to adaptive immunity, showing it regulates MHC class II–peptide complex formation and delivery for T-cell activation.","evidence":"RNAi silencing in dendritic cells with MHC II complex and T-cell activation assays","pmids":["25637027"],"confidence":"Medium","gaps":["Molecular effectors in MHC II compartment not identified","Link to HOPS/fusion machinery not tested"]},{"year":2016,"claim":"Connected ARL8B-driven anterograde lysosome positioning to extracellular cues and invasive cancer phenotypes.","evidence":"RNAi, 3D invasion and lysosome positioning assays, xenograft model","pmids":["27105540"],"confidence":"Medium","gaps":["Signaling pathway from receptors to ARL8B not mapped here","Protease/cargo identity in ECM degradation not defined"]},{"year":2016,"claim":"Identified RNF167-mediated ubiquitination of ARL8B at K141 as a degradative regulatory input controlling its protein level and positioning function.","evidence":"BioID, ubiquitination assay, K141R mutagenesis, lysosome positioning and trafficking assays","pmids":["27808481"],"confidence":"High","gaps":["Deubiquitinase counterpart not identified","Signals triggering RNF167 activity unknown"]},{"year":2017,"claim":"Mapped the upstream loading machinery, showing BORC/lyspersin recruits ARL8B to lysosomes and LAMTOR antagonizes this in a growth-factor-responsive manner.","evidence":"Domain deletion, co-IP, lysosome positioning, EGF stimulation","pmids":["28993467"],"confidence":"High","gaps":["GEF that loads GTP onto ARL8B not identified","Direct lyspersin-ARL8B contact not biochemically defined"]},{"year":2017,"claim":"Demonstrated ARL8B's physiological role in lysosomal degradation during development using genetic mouse models.","evidence":"Gene-trap and conditional KO mice, immunofluorescence, free amino acid measurement","pmids":["28827407"],"confidence":"High","gaps":["Tissue-specific effectors not dissected","Mechanism of cargo accumulation step not pinpointed"]},{"year":2018,"claim":"Showed ARL8B drives lysosomal exocytosis for plasma-membrane repair, determining macrophage cell-death fate during infection.","evidence":"RNAi, membrane repair and exocytosis assays, M. tuberculosis macrophage model","pmids":["29592961"],"confidence":"Medium","gaps":["Exocytic fusion machinery downstream of ARL8B not defined","Ca2+-trigger link not addressed"]},{"year":2019,"claim":"Revealed pathogen manipulation of ARL8B abundance and positioning to suppress autophagic flux.","evidence":"RNAi, tandem RFP-GFP-LC3 flux assay, in vitro vesicle fusion assay (HCV model)","pmids":["31383738"],"confidence":"Medium","gaps":["Mechanism of HCV-induced ARL8B upregulation unknown","Whether fusion machinery is directly affected unclear"]},{"year":2019,"claim":"Linked ARL8B loss to dorsal neural tube development and BMP signaling, extending its role to morphogenesis.","evidence":"Gene-trap KO mice, IHC, in situ hybridization, BMP pathway western blots","pmids":["31038803"],"confidence":"Medium","gaps":["BMP pathway placement is correlative, not directly tested","Lysosomal mechanism connecting ARL8B to BMP signaling unknown"]},{"year":2020,"claim":"Established that ARL8B controls neuronal axon branch density and position by spatially distributing lysosomes and autophagosomes.","evidence":"shRNA, overexpression, in vivo atg7 conditional KO, rapamycin treatment in retinal ganglion cells","pmids":["32917789"],"confidence":"Medium","gaps":["Molecular link between lysosome position and branching unresolved","Effector specificity in neurons not defined"]},{"year":2020,"claim":"Connected radiation-induced ARL8B–SKIP binding and BORC regulation to lysosomal exocytosis and cancer invasiveness/metastasis.","evidence":"Co-IP, RNAi, exocytosis assay, in vivo tumor model","pmids":["33110168"],"confidence":"Medium","gaps":["Signaling upstream of increased ARL8B-SKIP binding unclear","Exocytic cargo driving invasion not identified"]},{"year":2022,"claim":"Identified RUFY3 as an ARL8B effector coupling the GTPase to the JIP4–dynein–dynactin retrograde motor, defining a bidirectional positioning system.","evidence":"Reciprocal co-IP, RNAi, positioning and colocalization imaging, PIKFYVE rescue","pmids":["35314681"],"confidence":"High","gaps":["Switch between RUFY3 and anterograde adaptors not defined","Direct dynein-RUFY3 contact specifics not resolved"]},{"year":2022,"claim":"Showed ARL8B controls RUFY1 endosomal localization and CI-M6PR retrieval, expanding its role to endosome-to-TGN cargo retrieval.","evidence":"Co-IP, RNAi, CI-M6PR trafficking and dynein interaction assays, EM","pmids":["36282215"],"confidence":"High","gaps":["How ARL8B regulates RUFY1-Rab14 interaction mechanistically unclear","Relationship between RUFY1 and RUFY3 pathways undefined"]},{"year":2024,"claim":"Defined the ARL8B→DENND6A→Rab34→RILP/dynein retrograde cascade governing nutrient-dependent juxtanuclear lysosome repositioning.","evidence":"Cell-based GEF activity assay, co-IP, loss-of-function, positioning and autophagic flux assays","pmids":["38296963"],"confidence":"High","gaps":["Coordination with the RUFY3 retrograde route unresolved","Nutrient-sensing input to ARL8B not mapped"]},{"year":2024,"claim":"Linked ARL8B to RAB2A activation and MAPK/ERK signaling in hepatocellular carcinoma, suggesting a signaling role beyond trafficking.","evidence":"Mass spectrometry, co-IP, GTP-RAB2A pull-down, ERK phosphorylation assay","pmids":["39413890"],"confidence":"Medium","gaps":["Mechanistic link between ARL8B and ERK via RAB2A not fully validated","Whether ARL8B acts as a RAB2A GEF unknown"]},{"year":2023,"claim":"Discovered the GDP-conformation-dependent lipid-droplet localization of ARL8B and its role in LD–lysosome lipid transfer, revealing a second organelle function.","evidence":"Fluorescence microscopy, GDP/GTP conformational analysis, contact-site and lipid-transfer assays in macrophages","pmids":["37777960"],"confidence":"High","gaps":["Lipid-transfer protein partner at the contact not identified","Switch between LD and lysosome pools in vivo not quantified"]},{"year":2025,"claim":"Extended VPS41-ARL8B interaction to biosynthetic LAMP carrier trafficking, mapping the WD40 domain as the binding determinant.","evidence":"Ectopic VPS41 mis-targeting, RUSH LAMP tracking, EM, binding assay","pmids":["39907656"],"confidence":"High","gaps":["Regulation of carrier vs fusion VPS41 functions undefined","Whether other HOPS subunits are involved in carrier capture unclear"]},{"year":2023,"claim":"Showed ARL8B interacts with RAB5A to promote ITGB1 endosomal recycling and FAK signaling in osteocytes, defining a cargo-protective trafficking role.","evidence":"Co-IP, GST pull-down, lysosome IP, surface biotinylation, ITGB1 trafficking assay","pmids":["41163020"],"confidence":"Medium","gaps":["Direct vs indirect ARL8B-RAB5A interaction not fully resolved","Mechanism diverting ITGB1 from degradation unclear"]},{"year":2026,"claim":"Demonstrated ARL8B recruits the Rab11a GAP TBC1D9B to bias cargo from plasma-membrane recycling toward lysosomal delivery, integrating it with recycling control.","evidence":"RUSH assay, RNAi, GAP recruitment, LAMP1 and CI-M6PR trafficking assays","pmids":["42166252"],"confidence":"High","gaps":["Direct ARL8B-TBC1D9B binding interface not mapped","Coordination with RUFY1 retrieval pathway unresolved"]},{"year":2026,"claim":"Identified RNF13 as a second E3 ligase binding ARL8B and controlling its degradation and lysosome positioning, refining the ubiquitin-regulation model.","evidence":"Predictive structural modeling, co-IP, residue-level mutagenesis (Glu22/Phe55), positioning and EGFR trafficking assays","pmids":["42206902"],"confidence":"Medium","gaps":["Structural model is predictive, not experimentally determined","Overlap/redundancy with RNF167 not tested"]},{"year":null,"claim":"How the multiple ARL8B effector arms (SKIP-kinesin, RUFY3, DENND6A-Rab34, RUFY1, TBC1D9B) are dynamically coordinated, and the identity of the GEF that loads GTP onto lysosomal ARL8B, remain open.","evidence":"","pmids":[],"confidence":"High","gaps":["No ARL8B GEF identified in the corpus","Mechanism switching anterograde vs retrograde effector selection undefined","Integration of signaling (RAB2A/ERK) and trafficking functions unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[0,19]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,16,20]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[4,5,22]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[19]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[0,2,5]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]},{"term_id":"GO:0005811","term_label":"lipid droplet","supporting_discovery_ids":[19]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[16,23,24]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[2,5,16,20,24]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,17,22]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,4,6,11]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[12,14,20]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[10,19]}],"complexes":["ARL8B-SKIP-kinesin-1 complex","HOPS complex (effector)","BORC (upstream loading)"],"partners":["KIF5B","VPS41","RUFY3","RUFY1","DENND6A","TBC1D9B","RNF167","RNF13"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NVJ2","full_name":"ADP-ribosylation factor-like protein 8B","aliases":["ADP-ribosylation factor-like protein 10C","Novel small G protein indispensable for equal chromosome segregation 1"],"length_aa":186,"mass_kda":21.5,"function":"Small GTPase which cycles between active GTP-bound and inactive GDP-bound states (PubMed:15331635, PubMed:16537643). In its active state, binds to a variety of effector proteins playing a key role in the regulation of lysosomal positioning which is important for nutrient sensing, natural killer cell-mediated cytotoxicity and antigen presentation. Along with its effectors, orchestrates lysosomal transport and fusion (PubMed:16537643, PubMed:16650381, PubMed:25898167, PubMed:27808481, PubMed:28325809). Localizes specifically to lysosomal membranes and mediates anterograde lysosomal motility by recruiting PLEKHM2, which in turn recruits the motor protein kinesin-1 on lysosomes. Required for lysosomal and cytolytic granule exocytosis (PubMed:22172677, PubMed:24088571, PubMed:29592961). Critical factor involved in NK cell-mediated cytotoxicity. Drives the polarization of cytolytic granules and microtubule-organizing centers (MTOCs) toward the immune synapse between effector NK lymphocytes and target cells (PubMed:24088571). In neurons, mediates the anterograde axonal long-range transport of presynaptic lysosome-related vesicles required for presynaptic biogenesis and synaptic function (By similarity). Also acts as a regulator of endosome to lysosome trafficking pathways of special significance for host defense (PubMed:21802320). Recruits RUFY1 onto early endosomes regulating endosomes to trans-Golgi network proteins retrieval (PubMed:36282215). Regulates cargo trafficking to lysosomes by binding to PLEKHM1 and recruiting the HOPS subunit VPS41, resulting in functional assembly of the HOPS complex on lysosomal membranes (PubMed:16537643, PubMed:25908847). Plays an important role in cargo delivery to lysosomes for antigen presentation and microbial killing. Directs the intersection of CD1d with lipid antigens in lysosomes, and plays a role in intersecting phagosomes with lysosomes to generate phagolysosomes that kill microbes (PubMed:21802320, PubMed:25908847). Involved in the process of MHC II presentation. Regulates the delivery of antigens to lysosomes and the formation of MHC II-peptide complexes through the recruitment of the HOPS complex to lysosomes allowing the fusion of late endosomes to lysosomes (By similarity). May play a role in chromosome segregation (PubMed:15331635) (Microbial infection) During Mycobacterium tuberculosis (Mtb) infection, is required for plasma membrane repair by controlling the exocytosis of lysosomes in macrophages. ARL8B secretion pathway is crucial to control the type of cell death of the M.tuberculosis-infected macrophages, distinguishing avirulent from virulent Mtb induced necrotic cell death (Microbial infection) During infection, coronaviruses such as SARS-CoV-2 and the chaperone HSPA5/GRP78 are probably co-released through ARL8B-dependent lysosomal exocytic pathway for unconventional egress","subcellular_location":"Late endosome membrane; Lysosome membrane; Cytoplasm, cytoskeleton, spindle; Cell projection, axon; Synapse; Cytolytic granule membrane; Early endosome membrane","url":"https://www.uniprot.org/uniprotkb/Q9NVJ2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ARL8B","classification":"Not Classified","n_dependent_lines":124,"n_total_lines":1208,"dependency_fraction":0.10264900662251655},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000134108","cell_line_id":"CID000496","localizations":[{"compartment":"vesicles","grade":3}],"interactors":[{"gene":"YWHAH","stoichiometry":10.0},{"gene":"ARL8A","stoichiometry":10.0},{"gene":"YWHAG","stoichiometry":4.0},{"gene":"RAB7A","stoichiometry":4.0},{"gene":"LAMP1","stoichiometry":4.0},{"gene":"TMEM192","stoichiometry":0.2},{"gene":"YWHAZ","stoichiometry":0.2},{"gene":"YWHAE","stoichiometry":0.2},{"gene":"CAMSAP3","stoichiometry":0.2},{"gene":"APPL1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000496","total_profiled":1310},"omim":[{"mim_id":"619438","title":"N-ALPHA-ACETYLTRANSFERASE 35, NatC AUXILIARY SUBUNIT; NAA35","url":"https://www.omim.org/entry/619438"},{"mim_id":"619389","title":"SPINOCEREBELLAR ATAXIA, AUTOSOMAL RECESSIVE 29; SCAR29","url":"https://www.omim.org/entry/619389"},{"mim_id":"617990","title":"N-ALPHA-ACETYLTRANSFERASE 38, NatC AUXILIARY SUBUNIT; NAA38","url":"https://www.omim.org/entry/617990"},{"mim_id":"617989","title":"N-ALPHA-ACETYLTRANSFERASE 30, NatC CATALYTIC SUBUNIT; NAA30","url":"https://www.omim.org/entry/617989"},{"mim_id":"616601","title":"BLOC1-RELATED COMPLEX, SUBUNIT 8; BORCS8","url":"https://www.omim.org/entry/616601"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ARL8B"},"hgnc":{"alias_symbol":["FLJ10702","Gie1"],"prev_symbol":["ARL10C"]},"alphafold":{"accession":"Q9NVJ2","domains":[{"cath_id":"3.40.50.300","chopping":"18-181","consensus_level":"medium","plddt":94.763,"start":18,"end":181}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NVJ2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NVJ2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NVJ2-F1-predicted_aligned_error_v6.png","plddt_mean":92.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ARL8B","jax_strain_url":"https://www.jax.org/strain/search?query=ARL8B"},"sequence":{"accession":"Q9NVJ2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NVJ2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NVJ2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NVJ2"}},"corpus_meta":[{"pmid":"21802320","id":"PMC_21802320","title":"Lysosomal 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microscopy, GTP-restricted mutant expression, co-localization with lysosomal markers\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct localization experiment with functional consequence (lysosome redistribution), single lab, single method\",\n      \"pmids\": [\"16650381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The human NatC complex (hNatC), containing catalytic subunit hMak3, acetylates Met-Leu protein N-termini in vitro; knockdown of hMAK3 alters subcellular localization of ARL8B, supporting ARL8B as an in vivo substrate of hNatC-mediated N-terminal acetylation.\",\n      \"method\": \"In vitro acetyltransferase assay, siRNA knockdown, subcellular localization imaging\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro enzymatic assay plus cellular knockdown showing localization change, single lab, two orthogonal methods\",\n      \"pmids\": [\"19398576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Arl8b is required for cargo delivery to lysosomes; HOPS complex members (homotypic fusion and vacuole protein sorting complex) are effectors of Arl8b and depend on Arl8b for their recruitment to lysosomes, establishing an Arl8b-HOPS axis that directs lysosomal trafficking.\",\n      \"method\": \"shRNA library screen, RNAi knockdown, immunofluorescence co-localization, phagosome-lysosome fusion assay, CD1 antigen presentation assay\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal functional assays (trafficking, fusion, antigen presentation) plus effector identification, replicated across cell types\",\n      \"pmids\": [\"21802320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Salmonella exploits Arl8b on Salmonella-containing vacuoles (SCVs) to recruit kinesin-1, driving tubulated endosome (SIF) formation, SCV migration to the cell periphery, and cell-to-cell bacterial transfer.\",\n      \"method\": \"Bacterial infection model, RNAi knockdown, immunofluorescence for kinesin-1 recruitment, LAMP1-tubule formation assay\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined cellular phenotypes and kinesin-1 recruitment readout, single lab\",\n      \"pmids\": [\"21824248\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Arl8b is required for NK cell cytotoxicity by driving polarization of lytic granules and MTOCs toward the immune synapse; kinesin-1 heavy chain KIF5B was identified as an Arl8b interaction partner via GST pull-down, and the Arl8b–SKIP–kinesin-1 tripartite complex mediates anterograde granule movement.\",\n      \"method\": \"GST pull-down, shRNA knockdown, lytic granule polarization assay, cytotoxicity assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — direct biochemical interaction (GST pull-down) combined with functional loss-of-function showing specific NK cytotoxicity phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"24088571\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Arl8b, but not Rab7, is essential for membrane localization of hVps41, the HOPS complex subunit; Arl8b-dependent lysosomal localization of hVps41 is required for EGFR endocytic degradation, as an Arl8b-binding-defective mutant of hVps41 fails to rescue EGFR degradation. Additionally, Arl8b effector SKIP interacts with and recruits HOPS subunits to peripheral lysosomes.\",\n      \"method\": \"RNAi depletion, rescue with Arl8b-binding-defective mutant, EGFR degradation assay, co-immunoprecipitation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — mutant rescue experiment plus RNAi with functional readout and co-IP, multiple orthogonal methods in single lab\",\n      \"pmids\": [\"25908847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Arl8b localizes to MHC class II compartments in dendritic cells and regulates formation of MHC II–peptide complexes and their delivery to the plasma membrane for T cell activation.\",\n      \"method\": \"RNAi silencing, immunofluorescence localization, MHC II–peptide complex formation assay, T cell activation assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined immunological functional readouts, direct localization, single lab\",\n      \"pmids\": [\"25637027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Arl8b regulates anterograde lysosome trafficking to the cell periphery in response to HGF, EGF, and acidic extracellular pH; depletion of Arl8b impairs invasive growth and proteolytic ECM degradation in 3D prostate cancer models and abolishes xenograft formation in mice.\",\n      \"method\": \"RNAi knockdown, 3D invasion assay, lysosome positioning assay, xenograft mouse model\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with multiple phenotypic readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"27105540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"RNF167, a RING-domain E3 ubiquitin ligase, ubiquitinates Arl8B at lysine K141, reducing Arl8B protein levels; RNF167 overexpression/knockdown correspondingly alters Arl8b-dependent lysosome positioning and endocytic trafficking, and an ubiquitination-defective Arl8B K141R mutant counteracts RNF167 effects.\",\n      \"method\": \"Proximity-dependent biotin labeling (BioID), ubiquitination assay, site-directed mutagenesis (K141R), lysosome positioning assay, endocytic trafficking assay\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct biochemical ubiquitination assay, mutagenesis identifying site, functional rescue with mutant, multiple orthogonal methods single lab\",\n      \"pmids\": [\"27808481\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The C-terminal domain of lyspersin (a BORC subunit) is essential and sufficient for BORC-dependent recruitment of Arl8b to lysosomes; LAMTOR negatively regulates this process by associating with BORC, and EGF stimulation reduces LAMTOR/BORC association to promote Arl8b-dependent centrifugal lysosomal transport.\",\n      \"method\": \"Domain deletion analysis, co-immunoprecipitation, lysosome positioning assay, EGF stimulation\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain mapping with functional readout, co-IP, upstream regulatory mechanism identified, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"28993467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Arl8b is required for lysosomal degradation of maternal proteins in the visceral yolk sac endoderm; Arl8b gene-trap and conditional knockout mice show defective endocytic trafficking to lysosomes, accumulation of maternal proteins (albumin, IgG) in late endocytic organelles, reduced free amino acids in embryos, and decreased embryo body size.\",\n      \"method\": \"Gene-trap mouse model, conditional knockout (Transthyretin-Cre), immunofluorescence, free amino acid measurement\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout with defined molecular and developmental phenotypes, two independent genetic models\",\n      \"pmids\": [\"28827407\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Arl8b is required for lysosomal exocytosis-mediated plasma membrane repair; Arl8b-depleted cells fail to repair plasma membrane damage induced by M. tuberculosis, causing necrosis instead of apoptosis in macrophages infected with avirulent H37Ra.\",\n      \"method\": \"RNAi knockdown, plasma membrane repair assay, lysosomal exocytosis assay, macrophage infection model\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with mechanistically defined cellular phenotype (exocytosis, cell death type), single lab, multiple readouts\",\n      \"pmids\": [\"29592961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HCV infection increases Arl8b expression ~3-fold and redistributes it to a peripheral pattern that fails to co-localize with LC3-positive autophagosomes; knockdown of Arl8b in HCV-infected cells restores autophagosome-lysosome fusion and autophagic flux, demonstrating that HCV suppresses autophagic flux by upregulating and repositioning Arl8b.\",\n      \"method\": \"RNAi knockdown, tandem RFP-GFP-LC3 autophagic flux assay, in vitro vesicle fusion assay, immunofluorescence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function restores flux, in vitro fusion assay distinguishes trafficking vs. fusion defect, single lab\",\n      \"pmids\": [\"31383738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Loss of Arl8b in mice disrupts dorsal neural tube development, including ectopic Sox1 expression in the roof plate and elevated BMP receptor IA and phospho-Smad 1/5/8 signaling in the neural fold, suggesting Arl8b regulates BMP signaling during neural tube development.\",\n      \"method\": \"Gene-trap knockout mice, immunohistochemistry, in situ hybridization, western blot for BMP pathway components\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic KO with defined molecular phenotype, but pathway placement (BMP signaling) is correlative rather than directly tested, single lab\",\n      \"pmids\": [\"31038803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Arl8b controls density and position of interstitial axon branches in retinal ganglion cells by spatially controlling the location and density of lysosomes and autophagosomes along the axon shaft; Arl8b downregulation reduces branch density and shifts branches proximally, while overexpression increases density and positions branches more distally.\",\n      \"method\": \"shRNA knockdown, overexpression, immunofluorescence, in vivo conditional knockout (atg7), rapamycin treatment\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function with quantitative phenotypic readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"32917789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Arl8b binding to its effector SKIP is increased after radiation through regulation of BORC subunits; Arl8b and BORC-mediated lysosomal exocytosis drives invasiveness of radiation-surviving cancer cells, and in vivo Arl8b ablation decreases IR-induced invasive tumor growth and metastasis.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, lysosomal exocytosis assay, in vivo mouse tumor model\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP showing increased Arl8b-SKIP binding post-radiation, loss-of-function in vivo with defined metastasis readout, single lab\",\n      \"pmids\": [\"33110168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RUFY3 is an Arl8b effector that regulates retrograde lysosomal transport; RUFY3 interacts with the JIP4-dynein-dynactin complex and facilitates Arl8b association with the retrograde motor complex. RUFY3 knockdown disrupts Arl8b-positive endosome positioning, reduces Arl8b colocalization with Rab7-marked compartments, and reduces lysosome size (rescued by PIKFYVE inhibition).\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, lysosome positioning assay, co-localization imaging, PIKFYVE inhibitor rescue\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, loss-of-function with multiple defined phenotypes and rescue experiment, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"35314681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Arl8b binds RUFY1 and determines RUFY1 endosomal localization by regulating its interaction with Rab14; RUFY1 mediates endosome-to-TGN retrieval of CI-M6PR via the dynein-dynactin complex, and RUFY1 depletion delays CI-M6PR retrieval and impairs lysosomal cargo (cathepsin) delivery.\",\n      \"method\": \"Co-immunoprecipitation, RNAi depletion, CI-M6PR trafficking assay, dynein interaction assay, electron microscopy\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, loss-of-function with defined cargo trafficking readout and rescue, multiple orthogonal methods single lab\",\n      \"pmids\": [\"36282215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The Salmonella effector SifA mimics the Arl8a/Arl8b-SKIP pathway by recruiting kinesin-1 and kinesin-3 (KIF1Bβ) to Salmonella vacuoles; in the non-infectious context, SKIP is essential for kinesin-3 recruitment to a fraction of lysosomes downstream of Arl8b.\",\n      \"method\": \"Bacterial infection model, co-immunoprecipitation, kinesin recruitment assay, vacuole stability assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP and functional assays showing kinesin-3 recruitment via SKIP downstream of Arl8b, single lab\",\n      \"pmids\": [\"34878110\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ARL8B-GDP localizes to lipid droplets (LDs) via an exposed N-terminal amphipathic helix induced by GDP binding; ARL8B-GTP predominantly localizes to lysosomes. By associating with both organelles, ARL8B mediates LD-lysosome contacts and lipid transfer, serving as the major lipolytic pathway in human macrophages.\",\n      \"method\": \"Fluorescence microscopy, GDP/GTP conformational analysis, LD-lysosome contact site assay, lipid transfer assay, macrophage functional assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — conformational mechanism identified, organelle contact and lipid transfer directly measured, functional validation in macrophages, multiple orthogonal methods\",\n      \"pmids\": [\"37777960\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DENND6A is an Arl8b effector; Arl8b recruits DENND6A to peripheral lysosomes where DENND6A acts as a GEF activating Rab34, which then recruits a RILP/dynein complex to initiate lysosomal retrograde transport, regulating nutrient-dependent juxtanuclear lysosome repositioning and autophagic flux.\",\n      \"method\": \"GEF activity assay (cell-based), co-immunoprecipitation, loss-of-function, lysosome positioning assay, autophagic flux assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — GEF activity demonstrated, effector cascade mapped (Arl8b→DENND6A→Rab34→RILP/dynein) with functional consequences, multiple orthogonal methods single lab\",\n      \"pmids\": [\"38296963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ARL8B directly interacts with RAB2A (shown by mass spectrometry and co-IP) and increases GTP-bound RAB2A levels, activating the MAPK/ERK signaling pathway in hepatocellular carcinoma cells.\",\n      \"method\": \"Mass spectrometry, co-immunoprecipitation, GTP-RAB2A pull-down, ERK phosphorylation assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — co-IP and signaling assay, single lab, mechanistic link between ARL8B and ERK via RAB2A not fully validated\",\n      \"pmids\": [\"39413890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"VPS41 binds Arl8b via its WD40 domain; Arl8b is present on TGN-derived LAMP carriers and enables their recruitment by VPS41, expanding VPS41-Arl8b interactions beyond endosome-lysosome fusion to include biosynthetic LAMP carrier trafficking.\",\n      \"method\": \"Mitochondria mis-targeting (ectopic VPS41), RUSH system for newly synthesized LAMP tracking, electron microscopy, co-IP/binding assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — RUSH pulse-chase, ectopic localization assay, and binding domain identified with EM validation; multiple orthogonal methods single lab\",\n      \"pmids\": [\"39907656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ARL8B interacts with RAB5A (identified by co-IP and GST pull-down); ARL8B promotes RAB5A-mediated ITGB1 endosomal recycling and prevents ITGB1 lysosomal degradation, thereby maintaining ITGB1 levels and FAK signaling to support osteocyte dendritic process formation.\",\n      \"method\": \"Co-immunoprecipitation, GST pull-down, lysosome immunoprecipitation, cell surface biotinylation, ITGB1 trafficking assay\",\n      \"journal\": \"Stem cell research & therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — reciprocal pull-down showing ARL8B-RAB5A interaction with functional cargo trafficking readout, single lab\",\n      \"pmids\": [\"41163020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Arl8b localizes to post-endocytic LAMP1-containing vesicles and recruits the Rab11a GAP TBC1D9B to LAMP1-positive membranes, inactivating the Rab11a recycling pathway; without Arl8b, LAMP1 undergoes Rab11a-dependent recycling to the plasma membrane instead of lysosomal delivery. TBC1D9B knockdown also impairs CI-M6PR retrieval from Rab11a/Rab14 endosomes to the TGN, impairing cathepsin delivery.\",\n      \"method\": \"RUSH assay, RNAi depletion, Rab11a GAP recruitment assay, LAMP1 trafficking assay, CI-M6PR retrieval assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RUSH pulse-chase, loss-of-function with defined cargo trafficking phenotype, GAP recruitment mechanism identified, multiple orthogonal methods single lab\",\n      \"pmids\": [\"42166252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"RNF13 binds Arl8B via residues Glu22 and Phe55 of Arl8B (and Leu244 of RNF13) with modest preference for GDP-bound Arl8B; disrupting this interaction redistributes lysosomes to the cell periphery and selectively delays EGFR trafficking toward lysosomal degradation.\",\n      \"method\": \"Predictive structural modeling, co-immunoprecipitation, site-directed mutagenesis, lysosome positioning assay, EGFR trafficking assay\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Weak — co-IP with residue-level mutagenesis, functional readout, but structural model is predictive not experimental, single lab\",\n      \"pmids\": [\"42206902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"RNF13 mediates ubiquitin-dependent degradation of ARL8B; RNF13 activity is regulated by intracellular pH and Ca2+-bound ALG-2 (apoptosis-linked gene 2). Elevated pH_i deprotonates RNF13 at His332, enabling ALG-2 interaction and RNF13 activation, which reduces ARL8B levels and inhibits anterograde lysosomal transport; alkaline extracellular pH elevates lysosomal Ca2+ via TRPML3, further activating RNF13.\",\n      \"method\": \"pH manipulation, Ca2+ signaling assay, ubiquitination assay, lysosome positioning assay, RNF13 mutagenesis (His332), co-immunoprecipitation\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific mutagenesis identifying His332, multiple signaling inputs tested, functional readout, but preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ARL8B is a lysosome-resident Arf-like GTPase that, when GTP-bound, localizes to lysosomes and drives their anterograde (centrifugal) movement by recruiting the SKIP–kinesin-1 complex and, via DENND6A-Rab34-RILP, also coordinates retrograde transport through dynein; it recruits the HOPS tethering complex (via hVps41) to lysosomes to enable late endosome–lysosome fusion, LAMP carrier trafficking, and lysosomal cargo degradation, while in the GDP-bound state it additionally localizes to lipid droplets to mediate LD–lysosome contacts and lipid transfer; its activity is tuned by upstream regulators including BORC/lyspersin (which loads Arl8b onto lysosomes), LAMTOR (which antagonizes BORC), and post-translational modifications including NatC-mediated N-terminal acetylation and RNF167/RNF13-mediated ubiquitination at K141 that target it for degradation, collectively positioning Arl8b as a master organizer of lysosomal identity, positioning, fusion, biogenesis, and immune function.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ARL8B is a lysosome-resident Arf-like GTPase that functions as a master organizer of lysosomal positioning, fusion, biogenesis, and immune function [#0, #2]. In its GTP-bound state it localizes to lysosomal membranes, and constitutively active mutants redistribute lysosomes to the cell periphery, establishing GTP-dependent control of lysosomal spatial distribution [#0]. ARL8B drives anterograde, centrifugal lysosome transport by assembling a tripartite ARL8B–SKIP–kinesin-1 (KIF5B) complex, with SKIP also recruiting kinesin-3 (KIF1B\\u03b2) to a subset of lysosomes [#4, #18]. Opposing retrograde transport is coordinated through effectors RUFY3, which couples ARL8B to the JIP4–dynein–dynactin complex, and DENND6A, a GEF that activates Rab34 to recruit a RILP/dynein complex [#16, #20]. ARL8B also recruits the HOPS tethering complex to lysosomes—it is essential for membrane localization of the HOPS subunit hVps41/VPS41 (via its WD40 domain), enabling late endosome–lysosome fusion, endocytic cargo degradation including EGFR, and recruitment of TGN-derived biosynthetic LAMP carriers [#2, #5, #22]. Beyond degradative trafficking, ARL8B governs lysosomal cargo delivery by controlling endosomal recycling machinery: it recruits the Rab11a GAP TBC1D9B and determines the localization of RUFY1 and the retrieval of CI-M6PR, biasing cargo toward lysosomal delivery rather than plasma-membrane recycling [#17, #24]. In the GDP-bound conformation an exposed N-terminal amphipathic helix targets ARL8B to lipid droplets, where it mediates LD–lysosome contacts and lipid transfer as a major lipolytic route in macrophages [#19]. These activities underlie diverse cellular and immune processes including HOPS-dependent antigen presentation, NK-cell lytic granule polarization, lysosomal exocytosis for plasma-membrane repair, embryonic maternal-protein degradation, and axon-branch positioning [#2, #4, #10, #11, #14]. ARL8B activity is tuned by upstream BORC/lyspersin, which loads ARL8B onto lysosomes and is antagonized by LAMTOR, and by post-translational modifications: NatC-mediated N-terminal acetylation and RNF167/RNF13-mediated ubiquitination at K141 that target it for degradation [#1, #8, #9, #25].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that ARL8B is a lysosomal GTPase whose activity dictates organelle positioning, answering whether it has a defined subcellular role.\",\n      \"evidence\": \"Confocal immunofluorescence with a GTP-restricted mutant showing lysosome redistribution to the periphery\",\n      \"pmids\": [\"16650381\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular effectors of the positioning identified\", \"GTP-loading mechanism not addressed\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed ARL8B is regulated post-translationally, identifying NatC-mediated N-terminal acetylation as a determinant of its localization.\",\n      \"evidence\": \"In vitro acetyltransferase assay plus hMAK3 knockdown with localization imaging\",\n      \"pmids\": [\"19398576\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of mis-localization not quantified\", \"Direct acetylation of ARL8B not shown in cells\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined the ARL8B–HOPS axis and ARL8B's requirement for lysosomal cargo delivery, linking the GTPase to membrane fusion machinery and immune trafficking.\",\n      \"evidence\": \"shRNA screen, RNAi, phagosome-lysosome fusion and CD1 antigen presentation assays\",\n      \"pmids\": [\"21802320\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which HOPS subunit directly binds ARL8B not resolved here\", \"Anterograde motor link not yet established\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealed ARL8B is hijacked by pathogens to drive vacuole motility, demonstrating its kinesin-recruitment function in an infection context.\",\n      \"evidence\": \"Salmonella infection model with RNAi and kinesin-1 recruitment imaging\",\n      \"pmids\": [\"21824248\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ARL8B-kinesin interaction not biochemically shown\", \"Adaptor between ARL8B and kinesin-1 not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified the ARL8B–SKIP–kinesin-1 (KIF5B) tripartite complex and its role in NK-cell cytotoxicity, providing the biochemical basis for anterograde movement.\",\n      \"evidence\": \"GST pull-down for KIF5B interaction plus shRNA, granule polarization and cytotoxicity assays\",\n      \"pmids\": [\"24088571\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry/structure of the tripartite complex unresolved\", \"Regulation of complex assembly not defined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Established that ARL8B is required for membrane localization of HOPS subunit hVps41 and downstream EGFR degradation, ordering the ARL8B–SKIP–HOPS hierarchy.\",\n      \"evidence\": \"RNAi, Arl8b-binding-defective hVps41 rescue, EGFR degradation assay, co-IP\",\n      \"pmids\": [\"25908847\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ARL8B-hVps41 binding interface not mapped here\", \"Rab7-independence mechanism not fully explained\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extended ARL8B function to adaptive immunity, showing it regulates MHC class II–peptide complex formation and delivery for T-cell activation.\",\n      \"evidence\": \"RNAi silencing in dendritic cells with MHC II complex and T-cell activation assays\",\n      \"pmids\": [\"25637027\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular effectors in MHC II compartment not identified\", \"Link to HOPS/fusion machinery not tested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connected ARL8B-driven anterograde lysosome positioning to extracellular cues and invasive cancer phenotypes.\",\n      \"evidence\": \"RNAi, 3D invasion and lysosome positioning assays, xenograft model\",\n      \"pmids\": [\"27105540\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signaling pathway from receptors to ARL8B not mapped here\", \"Protease/cargo identity in ECM degradation not defined\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identified RNF167-mediated ubiquitination of ARL8B at K141 as a degradative regulatory input controlling its protein level and positioning function.\",\n      \"evidence\": \"BioID, ubiquitination assay, K141R mutagenesis, lysosome positioning and trafficking assays\",\n      \"pmids\": [\"27808481\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Deubiquitinase counterpart not identified\", \"Signals triggering RNF167 activity unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Mapped the upstream loading machinery, showing BORC/lyspersin recruits ARL8B to lysosomes and LAMTOR antagonizes this in a growth-factor-responsive manner.\",\n      \"evidence\": \"Domain deletion, co-IP, lysosome positioning, EGF stimulation\",\n      \"pmids\": [\"28993467\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"GEF that loads GTP onto ARL8B not identified\", \"Direct lyspersin-ARL8B contact not biochemically defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated ARL8B's physiological role in lysosomal degradation during development using genetic mouse models.\",\n      \"evidence\": \"Gene-trap and conditional KO mice, immunofluorescence, free amino acid measurement\",\n      \"pmids\": [\"28827407\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific effectors not dissected\", \"Mechanism of cargo accumulation step not pinpointed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed ARL8B drives lysosomal exocytosis for plasma-membrane repair, determining macrophage cell-death fate during infection.\",\n      \"evidence\": \"RNAi, membrane repair and exocytosis assays, M. tuberculosis macrophage model\",\n      \"pmids\": [\"29592961\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Exocytic fusion machinery downstream of ARL8B not defined\", \"Ca2+-trigger link not addressed\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed pathogen manipulation of ARL8B abundance and positioning to suppress autophagic flux.\",\n      \"evidence\": \"RNAi, tandem RFP-GFP-LC3 flux assay, in vitro vesicle fusion assay (HCV model)\",\n      \"pmids\": [\"31383738\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of HCV-induced ARL8B upregulation unknown\", \"Whether fusion machinery is directly affected unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linked ARL8B loss to dorsal neural tube development and BMP signaling, extending its role to morphogenesis.\",\n      \"evidence\": \"Gene-trap KO mice, IHC, in situ hybridization, BMP pathway western blots\",\n      \"pmids\": [\"31038803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"BMP pathway placement is correlative, not directly tested\", \"Lysosomal mechanism connecting ARL8B to BMP signaling unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established that ARL8B controls neuronal axon branch density and position by spatially distributing lysosomes and autophagosomes.\",\n      \"evidence\": \"shRNA, overexpression, in vivo atg7 conditional KO, rapamycin treatment in retinal ganglion cells\",\n      \"pmids\": [\"32917789\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between lysosome position and branching unresolved\", \"Effector specificity in neurons not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Connected radiation-induced ARL8B–SKIP binding and BORC regulation to lysosomal exocytosis and cancer invasiveness/metastasis.\",\n      \"evidence\": \"Co-IP, RNAi, exocytosis assay, in vivo tumor model\",\n      \"pmids\": [\"33110168\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signaling upstream of increased ARL8B-SKIP binding unclear\", \"Exocytic cargo driving invasion not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified RUFY3 as an ARL8B effector coupling the GTPase to the JIP4–dynein–dynactin retrograde motor, defining a bidirectional positioning system.\",\n      \"evidence\": \"Reciprocal co-IP, RNAi, positioning and colocalization imaging, PIKFYVE rescue\",\n      \"pmids\": [\"35314681\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Switch between RUFY3 and anterograde adaptors not defined\", \"Direct dynein-RUFY3 contact specifics not resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed ARL8B controls RUFY1 endosomal localization and CI-M6PR retrieval, expanding its role to endosome-to-TGN cargo retrieval.\",\n      \"evidence\": \"Co-IP, RNAi, CI-M6PR trafficking and dynein interaction assays, EM\",\n      \"pmids\": [\"36282215\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How ARL8B regulates RUFY1-Rab14 interaction mechanistically unclear\", \"Relationship between RUFY1 and RUFY3 pathways undefined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined the ARL8B→DENND6A→Rab34→RILP/dynein retrograde cascade governing nutrient-dependent juxtanuclear lysosome repositioning.\",\n      \"evidence\": \"Cell-based GEF activity assay, co-IP, loss-of-function, positioning and autophagic flux assays\",\n      \"pmids\": [\"38296963\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coordination with the RUFY3 retrograde route unresolved\", \"Nutrient-sensing input to ARL8B not mapped\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Linked ARL8B to RAB2A activation and MAPK/ERK signaling in hepatocellular carcinoma, suggesting a signaling role beyond trafficking.\",\n      \"evidence\": \"Mass spectrometry, co-IP, GTP-RAB2A pull-down, ERK phosphorylation assay\",\n      \"pmids\": [\"39413890\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between ARL8B and ERK via RAB2A not fully validated\", \"Whether ARL8B acts as a RAB2A GEF unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Discovered the GDP-conformation-dependent lipid-droplet localization of ARL8B and its role in LD–lysosome lipid transfer, revealing a second organelle function.\",\n      \"evidence\": \"Fluorescence microscopy, GDP/GTP conformational analysis, contact-site and lipid-transfer assays in macrophages\",\n      \"pmids\": [\"37777960\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Lipid-transfer protein partner at the contact not identified\", \"Switch between LD and lysosome pools in vivo not quantified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended VPS41-ARL8B interaction to biosynthetic LAMP carrier trafficking, mapping the WD40 domain as the binding determinant.\",\n      \"evidence\": \"Ectopic VPS41 mis-targeting, RUSH LAMP tracking, EM, binding assay\",\n      \"pmids\": [\"39907656\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Regulation of carrier vs fusion VPS41 functions undefined\", \"Whether other HOPS subunits are involved in carrier capture unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed ARL8B interacts with RAB5A to promote ITGB1 endosomal recycling and FAK signaling in osteocytes, defining a cargo-protective trafficking role.\",\n      \"evidence\": \"Co-IP, GST pull-down, lysosome IP, surface biotinylation, ITGB1 trafficking assay\",\n      \"pmids\": [\"41163020\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs indirect ARL8B-RAB5A interaction not fully resolved\", \"Mechanism diverting ITGB1 from degradation unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrated ARL8B recruits the Rab11a GAP TBC1D9B to bias cargo from plasma-membrane recycling toward lysosomal delivery, integrating it with recycling control.\",\n      \"evidence\": \"RUSH assay, RNAi, GAP recruitment, LAMP1 and CI-M6PR trafficking assays\",\n      \"pmids\": [\"42166252\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ARL8B-TBC1D9B binding interface not mapped\", \"Coordination with RUFY1 retrieval pathway unresolved\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified RNF13 as a second E3 ligase binding ARL8B and controlling its degradation and lysosome positioning, refining the ubiquitin-regulation model.\",\n      \"evidence\": \"Predictive structural modeling, co-IP, residue-level mutagenesis (Glu22/Phe55), positioning and EGFR trafficking assays\",\n      \"pmids\": [\"42206902\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural model is predictive, not experimentally determined\", \"Overlap/redundancy with RNF167 not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple ARL8B effector arms (SKIP-kinesin, RUFY3, DENND6A-Rab34, RUFY1, TBC1D9B) are dynamically coordinated, and the identity of the GEF that loads GTP onto lysosomal ARL8B, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No ARL8B GEF identified in the corpus\", \"Mechanism switching anterograde vs retrograde effector selection undefined\", \"Integration of signaling (RAB2A/ERK) and trafficking functions unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [0, 19]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 16, 20]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [4, 5, 22]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [0, 2, 5]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005811\", \"supporting_discovery_ids\": [19]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [16, 23, 24]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [2, 5, 16, 20, 24]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 17, 22]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 4, 6, 11]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [12, 14, 20]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [10, 19]}\n    ],\n    \"complexes\": [\"ARL8B-SKIP-kinesin-1 complex\", \"HOPS complex (effector)\", \"BORC (upstream loading)\"],\n    \"partners\": [\"KIF5B\", \"VPS41\", \"RUFY3\", \"RUFY1\", \"DENND6A\", \"TBC1D9B\", \"RNF167\", \"RNF13\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":9,"faith_total":9,"faith_pct":100.0}}