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Showing ARL5B — ARL8 is a alias.

ARL5B

ADP-ribosylation factor-like protein 5B · UniProt Q96KC2

Length
179 aa
Mass
20.4 kDa
Annotated
2026-06-09
26 papers in source corpus 16 papers cited in narrative 16 extracted findings
Cross-family judge faithfulness: 6/7 claims corpus-supported (86%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

ARL5B is an ARF-like small GTPase that operates at two membrane interfaces — the trans-Golgi network and the lysosome — to control membrane traffic in a nucleotide-dependent, effector-recruiting manner (PMID:22172677, PMID:22245584). At the TGN, ARL5B is required for retrograde endosome-to-Golgi transport: constitutively active ARL5B(Q70L) enhances, and depletion impairs, delivery of TGN38, Shiga toxin, and mannose-6-phosphate receptors back to the Golgi (PMID:22245584). It executes this role by physically associating with and recruiting the AP4 adaptor complex, thereby directing post-Golgi sorting of cargo such as APP, with loss of ARL5B causing Golgi accumulation of APP and elevated Aβ secretion (PMID:28000370). ARL5B also recruits the scaffold ACBD3 to the TGN (PMID:35789482), and its Golgi membrane association is fine-tuned by HSC70 in an ADP- and nucleotide-status-dependent manner, an interaction required for correct Golgi localization of the cation-independent mannose-6-phosphate receptor (PMID:34798070). In its lysosomal role, GTP-bound ARL5B/ARL8 directly binds the adaptor SKIP (PLEKHM2) and couples lysosomes to kinesin-1 for plus-end-directed, anterograde transport toward the cell periphery (PMID:22172677); this engagement both recruits SKIP and relieves its intramolecular autoinhibition to license kinesin-1 coupling (PMID:33232665). ARL5B/ARL8 additionally engages the HOPS complex via VPS-41 to drive phagosome–lysosome fusion (PMID:23485564) and, within a BORC–ARL8–HOPS ensemble, sustains lysosomal NPC2 delivery and free-cholesterol egress (PMID:35653304). Through these lysosomal functions ARL5B contributes to phagolysosomal biogenesis, autophagosome–lysosome fusion, and intracellular pathogen handling in macrophages (PMID:38332148, PMID:32250445).

Mechanistic history

Synthesis pass · year-by-year structured walk · 14 steps
  1. 2011 High

    Established how lysosomes are coupled to outward microtubule motility: active ARL8 was shown to directly bind the adaptor SKIP, physically linking lysosomal membranes to kinesin-1 for plus-end-directed transport.

    Evidence Affinity chromatography and lysosome-distribution assays with kinesin-light-chain motif mapping in SKIP

    PMID:22172677

    Open questions at the time
    • Did not define how SKIP recruitment is switched on/off
    • Nucleotide-exchange regulator of ARL8 not identified
  2. 2012 High

    Defined the canonical Golgi role of human ARL5B: it localizes to the TGN and is required for retrograde endosome-to-TGN cargo transport, distinguishing it from anterograde pathways.

    Evidence Confocal microscopy with Q70L/T30N mutants and RNAi with TGN38, Shiga toxin, M6PR and E-cadherin cargo readouts

    PMID:22245584

    Open questions at the time
    • Direct effectors at the TGN not identified
    • Relationship between TGN and lysosomal functions unresolved
  3. 2012 Medium

    Placed ARL8B in lysosome morphogenesis by showing it and SKIP are required for LPS-induced lysosome tubulation in macrophages.

    Evidence siRNA knockdown with fluorescence readout of lysosome tubulation

    PMID:22909026

    Open questions at the time
    • Single method/single lab
    • Mechanistic link between motor coupling and tubulation not dissected
  4. 2013 High

    Linked ARL8 to membrane fusion rather than just motility, showing the ortholog ARL-8 drives phagosome–lysosome fusion via the HOPS subunit VPS-41.

    Evidence C. elegans arl-8 loss-of-function genetics with phagosome maturation markers and ARL-8/VPS-41 co-IP

    PMID:23485564

    Open questions at the time
    • Mammalian confirmation of the VPS-41 interaction not shown here
    • How ARL8 toggles between HOPS and kinesin effectors unclear
  5. 2017 High

    Identified the molecular adaptor mechanism for ARL5B TGN cargo sorting: ARL5B physically associates with and recruits AP4 to direct APP export, with disease-relevant consequences for Aβ processing.

    Evidence Reciprocal co-IP, siRNA of ARL5B and AP4, and APP trafficking/Aβ secretion assays

    PMID:28000370

    Open questions at the time
    • Whether ARL5B-AP4 governs other cargoes not defined
    • Direct binding interface not resolved structurally
  6. 2018 Medium

    Showed ARL8 controls late endocytic transport via at least two distinct effectors and is required for neuronal axonal transport and synapse size.

    Evidence Drosophila genetics with neuron-specific rescue and affinity chromatography for HOPS and RILP

    PMID:30115618

    Open questions at the time
    • Effector switching logic not established
    • Mammalian relevance of RILP binding not tested here
  7. 2020 High

    Resolved the regulatory logic of SKIP activation, showing ARL8 binding disrupts SKIP intramolecular autoinhibition to license kinesin-1 coupling, with self-association further enhancing motor binding.

    Evidence Structure-function domain mutagenesis, co-IP/pull-down, and lysosome motility assays

    PMID:33232665

    Open questions at the time
    • No high-resolution structure of the ARL8–SKIP complex
    • Stoichiometry of self-association in cells unknown
  8. 2020 Medium

    Connected ARL8 to autophagy and infection control, showing elevated ARL8 blocks autophagosome–lysosome fusion and impairs bacterial clearance in stressed macrophages.

    Evidence siRNA knockdown in THP-1 macrophages with fusion and S. aureus survival assays

    PMID:32250445

    Open questions at the time
    • Single lab/single study
    • How ARL8 dosage shifts fusion outcome mechanistically unclear
  9. 2021 High

    Identified a chaperone-based control of ARL5B membrane targeting: HSC70 binds ARL5B in a nucleotide-status-dependent manner and fine-tunes its Golgi association and CIMPR localization.

    Evidence GBP pull-down/MS, ITC, fractionation, in vitro reconstitution and HSC70 knockdown

    PMID:34798070

    Open questions at the time
    • Whether HSC70 acts as a cycling/extraction factor in vivo not fully resolved
    • Effect on lysosomal pool of ARL5B not addressed
  10. 2022 Medium

    Mapped the TGN interactome of ARL5B, expanding its scaffold partners and showing it is required for ACBD3 recruitment.

    Evidence BioID and APEX2 proximity labelling plus GFP-Trap pull-down/MS with ACBD3 functional validation

    PMID:35789482

    Open questions at the time
    • Most identified neighbours not functionally validated
    • Direct vs. proximity interactions not distinguished
  11. 2022 Medium

    Defined a metabolic output of ARL8 lysosomal function within the BORC–ARL8–HOPS ensemble: it sustains NPC2 delivery and lysosomal cholesterol egress.

    Evidence siRNA of ARL8/BORC/HOPS with filipin cholesterol staining, NPC2 secretion and CI-MPR trafficking assays

    PMID:35653304

    Open questions at the time
    • Direct ARL8 contribution within the ensemble not isolated
    • Single lab
  12. 2024 Medium

    Implicated ARL5B in macrophage trafficking dynamics during infection, acting as a regulator of phagolysosomal biogenesis and a restriction factor for HRV16.

    Evidence RNA-seq discovery plus siRNA knockdown with bacterial killing, phagolysosome biogenesis and viral secretion readouts

    PMID:38332148

    Open questions at the time
    • Molecular basis of viral restriction not defined
    • Single lab
  13. 2025 Medium

    Defined an upstream transcriptional input to ARL5B, with ATF4 directly driving ARL5B expression and RPL41 limiting it via ATF4 degradation, affecting lysosomal trafficking and cell migration.

    Evidence ChIP, dual-luciferase reporter, Western blot and ARL5B overexpression rescue in retinoblastoma cells

    PMID:41451209

    Open questions at the time
    • Direct trafficking targets downstream not mapped
    • Single lab/single cancer context
  14. 2025 Low

    Linked ARL5B to lipogenic signalling in cancer via ROCK1-dependent SREBP1 activation, though without demonstrating direct ARL5B–ROCK1 binding.

    Evidence Knockdown/overexpression assays, ROCK1/SREBP1 pharmacological inhibition, nuclear fractionation and xenografts

    PMID:41144804

    Open questions at the time
    • No direct biochemical interaction between ARL5B and ROCK1 shown
    • Mechanism connecting a trafficking GTPase to SREBP1 unresolved
    • Single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • How ARL5B is spatially partitioned and nucleotide-cycled between its TGN retrograde role and its lysosomal motor/fusion roles, and what GEFs/GAPs govern this switch, remains unresolved.
  • No GEF/GAP identified in the corpus
  • No structural model of ARL5B–effector complexes
  • Determinants of TGN- vs. lysosome-targeting not defined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0003924 GTPase activity 2
Localization
GO:0005794 Golgi apparatus 4 GO:0005764 lysosome 3
Pathway
R-HSA-5653656 Vesicle-mediated transport 4 R-HSA-9609507 Protein localization 3 R-HSA-9612973 Autophagy 1
Partners
ACBD3GOPCHSC70PLEKHM2VPS41
Complex memberships
AP4HOPS

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2011 Arl8-GTP (active form) directly binds the soluble protein SKIP (PLEKHM2) via affinity chromatography; this interaction links lysosomal membranes to kinesin-1-driven plus-end-directed microtubule motility, enabling lysosomes to distribute away from the microtubule-organizing center toward the cell periphery. Affinity chromatography, overexpression/knockdown with lysosome distribution readout, identification of kinesin light chain binding motifs in SKIP Developmental Cell High 22172677
2020 ARL8 not only recruits SKIP to the lysosomal membrane but also relieves SKIP autoinhibition: the C-terminal PH domains of SKIP interact with its N-terminal ARL8- and kinesin-1-binding sites to autoinhibit coupling; ARL8 binding disrupts this intramolecular interaction, promoting kinesin-1-driven anterograde lysosome transport. Additionally, a disordered middle region of SKIP mediates self-association that enhances SKIP–kinesin-1 interaction. Structure-function analysis with domain deletions and mutants, lysosome motility assays, Co-IP/pull-down Current Biology High 33232665
2012 Arl5b (the canonical human ARL5B) localizes to the trans-Golgi network (TGN) and regulates retrograde membrane transport from endosomes to the TGN. Constitutively active Arl5b(Q70L) increases endosome-to-Golgi transport of TGN38; dominant-negative Arl5b(T30N) disperses to cytoplasm and perturbs Golgi. RNAi depletion of Arl5b reduces endosome-to-TGN transport of TGN38 and Shiga toxin and alters mannose-6-phosphate receptor distribution, but does not affect anterograde E-cadherin transport. Confocal microscopy with constitutively active/dominant-negative mutants, RNAi knockdown, cargo transport assays (TGN38, Shiga toxin, M6PR, E-cadherin) Experimental Cell Research High 22245584
2017 Arl5b localizes to the TGN and is physically associated with the AP4 adaptor complex. Arl5b is required for recruitment of AP4 (but not AP1) to the TGN and for direct post-Golgi transport of APP to early endosomes. Depletion of either Arl5b or AP4 causes APP to accumulate in the Golgi and increases Aβ secretion. Co-immunoprecipitation, siRNA knockdown, pulse-chase/trafficking assays, APP processing readout Traffic High 28000370
2021 Heat shock cognate protein HSC70 physically interacts with ARL5B in an ADP-dependent manner; the N-terminal helix and nucleotide status of ARL5B contribute to HSC70 recognition. HSC70 depletion reduces ARL5B Golgi localization, and in vitro reconstitution shows HSC70 fine-tunes ARL5B–Golgi membrane association. The ARL5B–HSC70 interaction is required for correct Golgi localization of the cation-independent mannose-6-phosphate receptor (CIMPR). GBP pull-down + mass spectrometry, isothermal titration calorimetry (ITC), confocal microscopy, cell fractionation, in vitro reconstitution, HSC70 knockdown Journal of Biological Chemistry High 34798070
2022 Proximity labelling (BioID, APEX2) and GFP-Trap pull-down identified 22 Golgi proteins as interacting partners/near-neighbours of Arl5b at the TGN, including TGN-localised Rabs, Arfs and Arls, and scaffold/tethering factors ACBD3 (GCP60) and PIST (GOPC). Arl5b was shown to be required for TGN recruitment of ACBD3. BioID proximity labelling, APEX2 proximity labelling, GFP-Trap pull-down, mass spectrometry, functional validation of ACBD3 recruitment FEBS Letters Medium 35789482
2013 C. elegans ARL-8 (ortholog of ARL8/ARL5B) localizes to lysosomes and is required for phagosome–lysosome fusion during apoptotic cell clearance. arl-8 loss-of-function mutants accumulate RAB-7-positive phagosomes that fail to fuse with lysosomes. ARL-8 physically interacts with the HOPS complex component VPS-41. C. elegans genetics (arl-8 loss-of-function), fluorescence microscopy of phagosome maturation markers, co-immunoprecipitation (ARL-8/VPS-41) Molecular Biology of the Cell High 23485564
2012 Arl8B and its effector SKIP are required for lysosome tubulation in macrophages exposed to LPS, placing Arl8B in the molecular pathway driving tubular lysosome biogenesis alongside Rab7/RILP/FYCO1. siRNA knockdown of Arl8B and SKIP with fluorescence microscopy readout of lysosome tubulation in LPS-treated macrophages Traffic Medium 22909026
2018 Drosophila Arl8 (ortholog) is essential for viability and normal late endocytic pathway function. In motor neurons, Arl8 is required for normal synapse size and efficient axonal transport. Affinity chromatography revealed Drosophila Arl8 binds the HOPS complex and the dynein adaptor RILP ortholog, indicating Arl8 controls late endocytic transport via at least two distinct effectors. Drosophila genetics (mutant clones, neuron-specific rescue), affinity chromatography for HOPS and RILP interactions, fluorescence microscopy of axonal cargo Biology Open Medium 30115618
2022 The BORC–ARL8–HOPS ensemble is required for lysosomal cholesterol egress: depletion of ARL8 (or BORC or HOPS) decreases NPC2 association with lysosomes (increasing NPC2 secretion) and increases lysosomal degradation of CI-MPR, thereby impairing NPC2 delivery and free cholesterol export from lysosomes. siRNA depletion of ARL8/BORC/HOPS subunits, cholesterol localization assays (filipin staining), NPC2 secretion assays, CI-MPR trafficking assays Molecular Biology of the Cell Medium 35653304
2024 ARL5b is upregulated in macrophages by HRV16 and its depletion rescues bacterial clearance and normalizes endosomal marker localization impaired by the virus, identifying ARL5b as a regulator of intracellular trafficking dynamics and phagolysosomal biogenesis in macrophages. In permissive epithelial cells, ARL5b depletion increases HRV16 secretion, indicating it acts as a restriction factor for HRV16. RNA sequencing (discovery), siRNA knockdown with bacterial killing assay, phagolysosome biogenesis assay, HRV16 virion secretion measurement EMBO Reports Medium 38332148
2020 Elevated ARL8 expression in advanced-glycation-end-product (AGE)-treated macrophages blocks autophagosome–lysosome fusion. Silencing ARL8 in AGE-treated macrophages restores autophagic flux and increases S. aureus clearance. siRNA knockdown of ARL8 in THP-1 macrophages, autophagosome–lysosome fusion assay (fluorescence microscopy), S. aureus intracellular survival assay European Journal of Immunology Medium 32250445
2025 ATF4 transcription factor positively regulates ARL5B expression (confirmed by ChIP and dual-luciferase assay). RPL41 promotes ATF4 degradation, thereby reducing ARL5B levels and impairing ARL5B-related lysosomal trafficking; ARL5B overexpression partially reverses RPL41-mediated inhibition of cell migration and lysosomal pathway activity in retinoblastoma cells. ChIP, dual-luciferase reporter, Western blotting, rescue experiments with ARL5B overexpression Frontiers in Immunology Medium 41451209
2025 ARL5B promotes ROCK1-dependent activation and nuclear translocation of SREBP1, enhancing lipogenic programming in esophageal squamous cell carcinoma. Pharmacological inhibition of ROCK1 or SREBP1 abrogates oncogenic effects of ARL5B overexpression, confirming functional dependency on the ROCK1–SREBP1 axis. Knockdown/overexpression functional assays, pharmacological inhibition of ROCK1/SREBP1, nuclear fractionation for SREBP1 translocation, in vivo xenograft Advanced Science Low 41144804
2025 In Drosophila, the novel dynein adaptor RUFY binds Arl8 on dense core vesicles, and together with Syd (dJIP3/4) forms a complex anchored to DCVs by Arl8 (activated by BORC) to recruit dynein for retrograde axonal transport. Loss of BORC (Arl8 activator) phenocopies loss of Syd, RUFY, Rab2, and dynein, producing axonal accumulation of immobile DCVs and reduced retrograde DCV flux. Drosophila genetics, pull-down (RUFY–Syd, RUFY–Arl8 interactions), live imaging of DCV axonal transport bioRxivpreprint Medium bio_10.1101_2025.05.28.656585
2024 A +1 programmatic ribosomal frameshifting event during PLEKHM2 (SKIP, the ARL8 effector) mRNA decoding generates a frameshifted proteoform whose new C-terminal domain relieves SKIP autoinhibition, allowing kinesin-1 association and cell-tip localization WITHOUT requiring activation by ARL8. Both the canonical and frameshifted PLEKHM2 proteins are necessary to restore normal contractile function in PLEKHM2-knockout cardiomyocytes. Ribosome profiling, frameshifting reporter assays, rescue of PLEKHM2-knockout cardiomyocytes, cell-tip localization assays bioRxivpreprint Medium bio_10.1101_2024.08.30.610563

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Arl8 and SKIP act together to link lysosomes to kinesin-1. Developmental cell 269 22172677
2020 The FTO/miR-181b-3p/ARL5B signaling pathway regulates cell migration and invasion in breast cancer. Cancer communications (London, England) 143 32805088
2012 Rab7 and Arl8 GTPases are necessary for lysosome tubulation in macrophages. Traffic (Copenhagen, Denmark) 105 22909026
2010 An Arf-like small G protein, ARL-8, promotes the axonal transport of presynaptic cargoes by suppressing vesicle aggregation. Neuron 100 20547129
2015 Arf-like GTPase Arl8: Moving from the periphery to the center of lysosomal biology. Cellular logistics 73 27057420
2017 Amyloid precursor protein traffics from the Golgi directly to early endosomes in an Arl5b- and AP4-dependent pathway. Traffic (Copenhagen, Denmark) 59 28000370
2011 A host small GTP-binding protein ARL8 plays crucial roles in tobamovirus RNA replication. PLoS pathogens 57 22174675
2020 ARL8 Relieves SKIP Autoinhibition to Enable Coupling of Lysosomes to Kinesin-1. Current biology : CB 47 33232665
2013 Arl8/ARL-8 functions in apoptotic cell removal by mediating phagolysosome formation in Caenorhabditis elegans. Molecular biology of the cell 39 23485564
2018 The small G protein Arl8 contributes to lysosomal function and long-range axonal transport in Drosophila. Biology open 33 30115618
2012 Arl5b is a Golgi-localised small G protein involved in the regulation of retrograde transport. Experimental cell research 29 22245584
2021 miR-145 inhibits mitochondrial function of ovarian cancer by targeting ARL5B. Journal of ovarian research 24 33419459
2018 Non-invasive force measurement reveals the number of active kinesins on a synaptic vesicle precursor in axonal transport regulated by ARL-8. Physical chemistry chemical physics : PCCP 17 29349444
2022 BORC-ARL8-HOPS ensemble is required for lysosomal cholesterol egress through NPC2. Molecular biology of the cell 14 35653304
2022 Parkinson disease-associated Leucine-rich repeat kinase regulates UNC-104-dependent axonal transport of Arl8-positive vesicles in Drosophila. iScience 12 36404922
2020 Advanced glycation end products reduce macrophage-mediated killing of Staphylococcus aureus by ARL8 upregulation and inhibition of autolysosome formation. European journal of immunology 11 32250445
2021 Binding with heat shock cognate protein HSC70 fine-tunes the Golgi association of the small GTPase ARL5B. The Journal of biological chemistry 7 34798070
2024 ARL5b inhibits human rhinovirus 16 propagation and impairs macrophage-mediated bacterial clearance. EMBO reports 6 38332148
2022 Interacting partners of Golgi-localized small G protein Arl5b identified by a combination of in vivo proximity labelling and GFP-Trap pull down. FEBS letters 6 35789482
2023 Circ-N4BP2L2 enhances mitochondrial function in non-small cell lung cancer cells through regulating the miR-135a-5p/ARL5B axis. Environmental toxicology 5 36637163
2007 The involvement of arl-5b in the repair of hair cells in sea anemones. Journal of the Association for Research in Otolaryngology : JARO 5 17332968
2003 Isolation of a new member of the ADP-ribosylation like factor gene family, ARL8, from a cartilage cDNA library. Gene 5 12853149
2022 Knockdown of ARL5B Induces Mitochondrial-mediated Apoptosis and Inhibits Glycolysis in Breast Cancer Cells by Activating MDA5 Signaling. Current cancer drug targets 4 35546774
2025 ARL5B Drives Esophageal Squamous Cell Carcinoma Progression via ROCK1-SREBP1-Mediated Lipid Metabolic Reprogramming. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 3 41144804
2025 miR-3150b-3p Promotes Vascular Smooth Muscle Cell Injury by Targeting ARL5B. Clinical and applied thrombosis/hemostasis : official journal of the International Academy of Clinical and Applied Thrombosis/Hemostasis 0 41384842
2025 RPL41 inhibits the proliferation and migration of retinoblastoma through the ARL5B-associated lysosomal trafficking. Frontiers in immunology 0 41451209

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