{"gene":"RAB36","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":1999,"finding":"RAB36 protein localizes to the Golgi body, as determined by transfection and subcellular localization experiments in the original cloning study.","method":"Transfection and subcellular localization (fluorescence/immunostaining)","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single lab, single localization experiment with no functional follow-up linking Golgi localization to a specific activity","pmids":["9920784"],"is_preprint":false},{"year":2010,"finding":"RAB36 associates with the Golgi apparatus (co-localizing with GM130, Syntaxin 5, and TGN46) and its overexpression induces clustering of late endosomes and lysosomes (marked by LBPA, CD63, LAMP1, LAMP2) around the Golgi, without affecting early endosomes (EEA1). RAB36 interacts with RILP via RILP's C-terminal region (aa199–401) as shown by GST pull-down.","method":"EGFP-tagged wild-type and GTPase mutant expression, co-localization with organelle markers, GST pull-down assay","journal":"Molecular membrane biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — multiple orthogonal methods (localization + GST pull-down) in a single lab, consistent with other reports of RILP interaction","pmids":["19961360"],"is_preprint":false},{"year":2010,"finding":"GAPCenA/TBC1D11 was identified as a RAB36-binding protein via GST pull-down with mammalian cell lysates, and the interaction occurs through a domain other than the TBC/GAP domain.","method":"GST pull-down assay with 60 mammalian Rabs combined with mass spectrometry","journal":"Traffic (Copenhagen, Denmark)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single pull-down screen, no functional follow-up on the RAB36–TBC1D11 interaction specifically","pmids":["20070612"],"is_preprint":false},{"year":2012,"finding":"RAB36 interacts with RILP family members (RILP, RILP-L1, RILP-L2) and JIP3/JIP4 via a conserved coiled-coil RILP homology domain (RHD). RAB36 mediates retrograde melanosome transport in melanocytes: expression of RILP (but not its RAB36 binding-deficient mutants) induced perinuclear melanosome aggregation, and this effect was attenuated by RAB36 knockdown. In RAB27A-deficient melanocytes, RAB36 knockdown caused melanosome dispersion from the perinucleus, whereas RAB7 knockdown did not.","method":"Yeast two-hybrid / binding screens, site-directed mutagenesis of RHD, siRNA knockdown in melanocytes, live-cell imaging of melanosome distribution","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (binding screens, mutagenesis, knockdown with specific phenotypic readout), replicated across conditions including Rab27A-KO cells","pmids":["22740695"],"is_preprint":false},{"year":2012,"finding":"RUTBC2, a TBC domain-containing protein and Rab9A effector, acts as a GTPase-activating protein (GAP) for RAB36 in vitro and in cells. Wild-type RUTBC2 co-localizes with membrane-associated RAB36 and decreases its membrane association, whereas the catalytically inactive RUTBC2 R829A mutant does not.","method":"Biochemical GAP activity screen against Rab panel in vitro, co-localization in cultured cells, expression of catalytically inactive mutant","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro GAP activity assay plus cell-based functional validation with catalytic mutant, single lab but multiple orthogonal methods","pmids":["22637480"],"is_preprint":false},{"year":2014,"finding":"RAB36 is recruited to Arf6-positive recycling endosomes downstream of RAB35 via the scaffold protein MICAL-L1. RAB35 recruits MICAL-L1, which in turn acts as a scaffold for RAB36 (and RAB8, RAB13). RAB36 knockdown inhibits recruitment of its effector JIP4 to these recycling endosomes and inhibits neurite outgrowth without affecting RAB8 or RAB13 accumulation at the same compartment.","method":"siRNA knockdown, live-cell imaging, co-localization, epistasis analysis in PC12 cells during NGF-induced neurite outgrowth","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis and localization experiments with defined phenotypic readout, single lab","pmids":["25086062"],"is_preprint":false},{"year":2019,"finding":"RAB36 promotes activation of myosin-5a motor function: RAB36 (as a binding partner of RILPL2) stimulates RILPL2 to interact with the myosin-5a globular tail domain (GTD), which in turn exposes the melanophilin (Mlph)-binding site in the GTD, enabling Mlph to interact with the GTD and activate myosin-5a ATPase and motility.","method":"ATPase assay, single-molecule motility assay, GST pull-down, analytical ultracentrifugation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple in vitro biochemical assays (ATPase, single-molecule motility, pull-down, AUC) establishing mechanism, single lab","pmids":["31175157"],"is_preprint":false},{"year":2021,"finding":"Rab34 (paralog) is a selective mediator of intracellular ciliogenesis, while its paralog RAB36 is not required for the extracellular ciliogenesis pathway used by MDCK cells (MDCK cells ciliate independently of Rab34 and its paralog Rab36).","method":"Knockout cell lines (MDCK), ciliogenesis assays","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean KO with defined phenotypic readout, but the RAB36 finding is a negative result (not required for extracellular ciliogenesis in MDCK), single lab","pmids":["33989527"],"is_preprint":false},{"year":2022,"finding":"RAB36 serves as a cargo receptor on melanosomes for microtubule-dependent retrograde transport. Simultaneous depletion of RAB36, melanoregulin, and Rab44 resulted in almost complete inhibition of retrograde melanosome transport, indicating RAB36 is one of at least three cargo receptors for this process.","method":"siRNA knockdown in mouse melanocytes (Rab27A-deficient melan-ash cells), melanosome distribution assays, triple-knockdown epistasis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis via triple knockdown with clear quantitative phenotypic readout, single lab","pmids":["36126775"],"is_preprint":false}],"current_model":"RAB36 is a Golgi-associated small GTPase that, in its active GTP-bound state, interacts with RILP-family effectors (via their RILP homology domain/RHD) and JIP3/JIP4 to drive microtubule-dependent retrograde transport of late endosomes/lysosomes and melanosomes; its membrane cycling is terminated by the Rab9A effector RUTBC2, which acts as a RAB36-GAP; additionally, RAB36 promotes myosin-5a motor activation through RILPL2 on melanosomes, and is recruited to Arf6-positive recycling endosomes via MICAL-L1 downstream of RAB35 to regulate neurite outgrowth."},"narrative":{"mechanistic_narrative":"RAB36 is a Golgi-associated small GTPase that drives microtubule-dependent retrograde transport of late endosomal/lysosomal and melanosomal compartments toward the perinuclear region [PMID:19961360, PMID:22740695]. In its active state it engages RILP-family effectors (RILP, RILP-L1, RILP-L2) and the JIP3/JIP4 scaffolds through a conserved coiled-coil RILP homology domain (RHD), and this interaction is required for RILP-induced perinuclear aggregation of melanosomes and late endosomes/lysosomes [PMID:19961360, PMID:22740695]. In melanocytes RAB36 functions as a cargo receptor that, together with melanoregulin and Rab44, mediates retrograde melanosome transport, and it independently activates the myosin-5a motor by promoting RILPL2 binding to the myosin-5a globular tail domain, thereby exposing the melanophilin-binding site and stimulating motor ATPase and motility [PMID:22740695, PMID:31175157, PMID:36126775]. RAB36 is also recruited to Arf6-positive recycling endosomes via MICAL-L1 acting downstream of RAB35, where it recruits its effector JIP4 to support neurite outgrowth [PMID:25086062]. Its membrane association is terminated by the Rab9A effector RUTBC2, which acts as a RAB36-specific GTPase-activating protein [PMID:22637480].","teleology":[{"year":1999,"claim":"Established the basic subcellular address of RAB36 by showing it localizes to the Golgi, providing the first spatial framework for its function.","evidence":"Transfection and subcellular localization in the original cloning study","pmids":["9920784"],"confidence":"Medium","gaps":["No functional activity linked to Golgi localization","No effector or pathway identified"]},{"year":2010,"claim":"Connected RAB36's Golgi localization to organelle positioning by showing overexpression clusters late endosomes/lysosomes perinuclearly and identifying RILP as a binding partner, defining a candidate retrograde transport role.","evidence":"EGFP-tagged WT/mutant expression, co-localization with organelle markers, GST pull-down","pmids":["19961360"],"confidence":"Medium","gaps":["Overexpression phenotype not validated by loss-of-function","Binding region on RAB36 not mapped","Motor machinery not identified"]},{"year":2010,"claim":"A Rab-wide interaction screen flagged GAPCenA/TBC1D11 as a RAB36 binding protein through a non-TBC domain, hinting at additional regulatory partners.","evidence":"GST pull-down of 60 mammalian Rabs with mass spectrometry","pmids":["20070612"],"confidence":"Low","gaps":["Single pull-down with no functional follow-up","Physiological relevance of the interaction unknown"]},{"year":2012,"claim":"Defined the effector logic of RAB36 by mapping its binding to the RHD of RILP-family proteins and JIP3/JIP4 and demonstrating, via knockdown, that RAB36 is required for retrograde melanosome transport independent of RAB7.","evidence":"Binding screens, RHD mutagenesis, siRNA in melanocytes including Rab27A-KO cells, live-cell imaging","pmids":["22740695"],"confidence":"High","gaps":["Direct motor adaptor at the melanosome not yet defined","GTP-dependence of effector engagement not biochemically dissected here"]},{"year":2012,"claim":"Identified the off-switch for RAB36 by showing the Rab9A effector RUTBC2 acts as its GAP and reduces RAB36 membrane association, placing RAB36 in a Rab9A-coupled regulatory circuit.","evidence":"In vitro GAP assay against a Rab panel, co-localization, catalytically inactive R829A mutant in cells","pmids":["22637480"],"confidence":"High","gaps":["GEF for RAB36 not identified","In vivo significance of RUTBC2-mediated inactivation untested"]},{"year":2014,"claim":"Placed RAB36 in a RAB35→MICAL-L1 recruitment cascade at Arf6-positive recycling endosomes, showing it recruits JIP4 there and is required for neurite outgrowth, broadening its role beyond melanosomes.","evidence":"siRNA, live-cell imaging, epistasis in NGF-stimulated PC12 cells","pmids":["25086062"],"confidence":"Medium","gaps":["Cargo transported in this pathway not defined","Mechanism linking JIP4 recruitment to outgrowth unresolved"]},{"year":2019,"claim":"Resolved a direct biochemical mechanism by which RAB36 activates the myosin-5a motor, showing it drives RILPL2 binding to the myosin-5a GTD to expose the melanophilin-binding site and stimulate motor activity.","evidence":"ATPase and single-molecule motility assays, GST pull-down, analytical ultracentrifugation","pmids":["31175157"],"confidence":"High","gaps":["Cellular reconstitution of this activation on melanosomes not shown","Integration with the retrograde (dynein) transport role unclear"]},{"year":2021,"claim":"Distinguished RAB36 from its paralog Rab34 in ciliogenesis, showing RAB36 is not required for the extracellular ciliogenesis pathway in MDCK cells.","evidence":"MDCK knockout cell lines and ciliogenesis assays","pmids":["33989527"],"confidence":"Medium","gaps":["Negative result; role in intracellular ciliogenesis not directly tested for RAB36","Other cell types not examined"]},{"year":2022,"claim":"Defined RAB36 as one of at least three redundant melanosomal cargo receptors for retrograde transport, with full inhibition only on combined depletion with melanoregulin and Rab44.","evidence":"Triple siRNA knockdown in Rab27A-deficient melan-ash cells, melanosome distribution assays","pmids":["36126775"],"confidence":"Medium","gaps":["Molecular basis of redundancy among the three receptors unresolved","Single-cell-type evidence"]},{"year":null,"claim":"The activating GEF for RAB36 and how its dynein-driven retrograde role is coordinated with myosin-5a activation on the same melanosome remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No GEF identified in the corpus","Coordination of opposing/cooperating motors mechanistically unresolved","In vivo physiological phenotype not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[4]},{"term_id":"GO:0038024","term_label":"cargo receptor activity","supporting_discovery_ids":[8]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,5]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,8]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[1,3]}],"complexes":[],"partners":["RILP","RILPL1","RILPL2","JIP3","JIP4","RUTBC2","MICAL-L1","TBC1D11"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O95755","full_name":"Ras-related protein Rab-36","aliases":[],"length_aa":267,"mass_kda":29.7,"function":"The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes. Rabs cycle between an inactive GDP-bound form and an active GTP-bound form that is able to recruit to membranes different sets of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion","subcellular_location":"Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/O95755/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RAB36","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":383,"dependency_fraction":0.0026109660574412533},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RAB36","total_profiled":1310},"omim":[{"mim_id":"610917","title":"RAS-ASSOCIATED PROTEIN 34; RAB34","url":"https://www.omim.org/entry/610917"},{"mim_id":"605663","title":"RADIAL SPOKE HEAD 14 HOMOLOG; RSPH14","url":"https://www.omim.org/entry/605663"},{"mim_id":"605662","title":"RAS-ASSOCIATED PROTEIN RAB36; RAB36","url":"https://www.omim.org/entry/605662"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"fallopian tube","ntpm":25.7}],"url":"https://www.proteinatlas.org/search/RAB36"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O95755","domains":[{"cath_id":"3.40.50.300","chopping":"89-300","consensus_level":"high","plddt":93.4181,"start":89,"end":300}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95755","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95755-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95755-F1-predicted_aligned_error_v6.png","plddt_mean":85.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RAB36","jax_strain_url":"https://www.jax.org/strain/search?query=RAB36"},"sequence":{"accession":"O95755","fasta_url":"https://rest.uniprot.org/uniprotkb/O95755.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95755/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95755"}},"corpus_meta":[{"pmid":"20070612","id":"PMC_20070612","title":"Comprehensive screening for novel rab-binding proteins by GST pull-down assay using 60 different mammalian Rabs.","date":"2010","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/20070612","citation_count":100,"is_preprint":false},{"pmid":"22740695","id":"PMC_22740695","title":"The Rab interacting lysosomal protein (RILP) homology domain functions as a novel effector domain for small GTPase Rab36: Rab36 regulates retrograde melanosome transport in melanocytes.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22740695","citation_count":75,"is_preprint":false},{"pmid":"25086062","id":"PMC_25086062","title":"Rab35 promotes the recruitment of Rab8, Rab13 and Rab36 to recycling endosomes through MICAL-L1 during neurite outgrowth.","date":"2014","source":"Biology open","url":"https://pubmed.ncbi.nlm.nih.gov/25086062","citation_count":71,"is_preprint":false},{"pmid":"36224588","id":"PMC_36224588","title":"Two circPPFIA1s negatively regulate liver metastasis of colon cancer via miR-155-5p/CDX1 and HuR/RAB36.","date":"2022","source":"Molecular cancer","url":"https://pubmed.ncbi.nlm.nih.gov/36224588","citation_count":53,"is_preprint":false},{"pmid":"33989527","id":"PMC_33989527","title":"Rab34 GTPase mediates ciliary membrane formation in the intracellular ciliogenesis pathway.","date":"2021","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/33989527","citation_count":50,"is_preprint":false},{"pmid":"19961360","id":"PMC_19961360","title":"Rab36 regulates the spatial distribution of late endosomes and lysosomes through a similar mechanism to Rab34.","date":"2010","source":"Molecular membrane biology","url":"https://pubmed.ncbi.nlm.nih.gov/19961360","citation_count":46,"is_preprint":false},{"pmid":"9920784","id":"PMC_9920784","title":"Cloning and characterization of a novel Rab-family gene, Rab36, within the region at 22q11.2 that is homozygously deleted in malignant rhabdoid tumors.","date":"1999","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/9920784","citation_count":31,"is_preprint":false},{"pmid":"22637480","id":"PMC_22637480","title":"RUTBC2 protein, a Rab9A effector and GTPase-activating protein for Rab36.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22637480","citation_count":30,"is_preprint":false},{"pmid":"18474292","id":"PMC_18474292","title":"BCR expression is decreased in meningiomas showing loss of heterozygosity of 22q within a new minimal deletion region.","date":"2008","source":"Cancer genetics and cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/18474292","citation_count":18,"is_preprint":false},{"pmid":"10607907","id":"PMC_10607907","title":"Isolation of genes from the rhabdoid tumor deletion region in chromosome band 22q11.2.","date":"2000","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/10607907","citation_count":16,"is_preprint":false},{"pmid":"22002912","id":"PMC_22002912","title":"The first case of myoclonic epilepsy in a child with a de novo 22q11.2 microduplication.","date":"2011","source":"American journal of medical genetics. 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RAB36 interacts with RILP via RILP's C-terminal region (aa199–401) as shown by GST pull-down.\",\n      \"method\": \"EGFP-tagged wild-type and GTPase mutant expression, co-localization with organelle markers, GST pull-down assay\",\n      \"journal\": \"Molecular membrane biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — multiple orthogonal methods (localization + GST pull-down) in a single lab, consistent with other reports of RILP interaction\",\n      \"pmids\": [\"19961360\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"GAPCenA/TBC1D11 was identified as a RAB36-binding protein via GST pull-down with mammalian cell lysates, and the interaction occurs through a domain other than the TBC/GAP domain.\",\n      \"method\": \"GST pull-down assay with 60 mammalian Rabs combined with mass spectrometry\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single pull-down screen, no functional follow-up on the RAB36–TBC1D11 interaction specifically\",\n      \"pmids\": [\"20070612\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RAB36 interacts with RILP family members (RILP, RILP-L1, RILP-L2) and JIP3/JIP4 via a conserved coiled-coil RILP homology domain (RHD). RAB36 mediates retrograde melanosome transport in melanocytes: expression of RILP (but not its RAB36 binding-deficient mutants) induced perinuclear melanosome aggregation, and this effect was attenuated by RAB36 knockdown. In RAB27A-deficient melanocytes, RAB36 knockdown caused melanosome dispersion from the perinucleus, whereas RAB7 knockdown did not.\",\n      \"method\": \"Yeast two-hybrid / binding screens, site-directed mutagenesis of RHD, siRNA knockdown in melanocytes, live-cell imaging of melanosome distribution\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (binding screens, mutagenesis, knockdown with specific phenotypic readout), replicated across conditions including Rab27A-KO cells\",\n      \"pmids\": [\"22740695\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RUTBC2, a TBC domain-containing protein and Rab9A effector, acts as a GTPase-activating protein (GAP) for RAB36 in vitro and in cells. Wild-type RUTBC2 co-localizes with membrane-associated RAB36 and decreases its membrane association, whereas the catalytically inactive RUTBC2 R829A mutant does not.\",\n      \"method\": \"Biochemical GAP activity screen against Rab panel in vitro, co-localization in cultured cells, expression of catalytically inactive mutant\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro GAP activity assay plus cell-based functional validation with catalytic mutant, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"22637480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"RAB36 is recruited to Arf6-positive recycling endosomes downstream of RAB35 via the scaffold protein MICAL-L1. RAB35 recruits MICAL-L1, which in turn acts as a scaffold for RAB36 (and RAB8, RAB13). RAB36 knockdown inhibits recruitment of its effector JIP4 to these recycling endosomes and inhibits neurite outgrowth without affecting RAB8 or RAB13 accumulation at the same compartment.\",\n      \"method\": \"siRNA knockdown, live-cell imaging, co-localization, epistasis analysis in PC12 cells during NGF-induced neurite outgrowth\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis and localization experiments with defined phenotypic readout, single lab\",\n      \"pmids\": [\"25086062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"RAB36 promotes activation of myosin-5a motor function: RAB36 (as a binding partner of RILPL2) stimulates RILPL2 to interact with the myosin-5a globular tail domain (GTD), which in turn exposes the melanophilin (Mlph)-binding site in the GTD, enabling Mlph to interact with the GTD and activate myosin-5a ATPase and motility.\",\n      \"method\": \"ATPase assay, single-molecule motility assay, GST pull-down, analytical ultracentrifugation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple in vitro biochemical assays (ATPase, single-molecule motility, pull-down, AUC) establishing mechanism, single lab\",\n      \"pmids\": [\"31175157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Rab34 (paralog) is a selective mediator of intracellular ciliogenesis, while its paralog RAB36 is not required for the extracellular ciliogenesis pathway used by MDCK cells (MDCK cells ciliate independently of Rab34 and its paralog Rab36).\",\n      \"method\": \"Knockout cell lines (MDCK), ciliogenesis assays\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean KO with defined phenotypic readout, but the RAB36 finding is a negative result (not required for extracellular ciliogenesis in MDCK), single lab\",\n      \"pmids\": [\"33989527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RAB36 serves as a cargo receptor on melanosomes for microtubule-dependent retrograde transport. Simultaneous depletion of RAB36, melanoregulin, and Rab44 resulted in almost complete inhibition of retrograde melanosome transport, indicating RAB36 is one of at least three cargo receptors for this process.\",\n      \"method\": \"siRNA knockdown in mouse melanocytes (Rab27A-deficient melan-ash cells), melanosome distribution assays, triple-knockdown epistasis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis via triple knockdown with clear quantitative phenotypic readout, single lab\",\n      \"pmids\": [\"36126775\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RAB36 is a Golgi-associated small GTPase that, in its active GTP-bound state, interacts with RILP-family effectors (via their RILP homology domain/RHD) and JIP3/JIP4 to drive microtubule-dependent retrograde transport of late endosomes/lysosomes and melanosomes; its membrane cycling is terminated by the Rab9A effector RUTBC2, which acts as a RAB36-GAP; additionally, RAB36 promotes myosin-5a motor activation through RILPL2 on melanosomes, and is recruited to Arf6-positive recycling endosomes via MICAL-L1 downstream of RAB35 to regulate neurite outgrowth.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RAB36 is a Golgi-associated small GTPase that drives microtubule-dependent retrograde transport of late endosomal/lysosomal and melanosomal compartments toward the perinuclear region [#1, #3]. In its active state it engages RILP-family effectors (RILP, RILP-L1, RILP-L2) and the JIP3/JIP4 scaffolds through a conserved coiled-coil RILP homology domain (RHD), and this interaction is required for RILP-induced perinuclear aggregation of melanosomes and late endosomes/lysosomes [#1, #3]. In melanocytes RAB36 functions as a cargo receptor that, together with melanoregulin and Rab44, mediates retrograde melanosome transport, and it independently activates the myosin-5a motor by promoting RILPL2 binding to the myosin-5a globular tail domain, thereby exposing the melanophilin-binding site and stimulating motor ATPase and motility [#3, #6, #8]. RAB36 is also recruited to Arf6-positive recycling endosomes via MICAL-L1 acting downstream of RAB35, where it recruits its effector JIP4 to support neurite outgrowth [#5]. Its membrane association is terminated by the Rab9A effector RUTBC2, which acts as a RAB36-specific GTPase-activating protein [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established the basic subcellular address of RAB36 by showing it localizes to the Golgi, providing the first spatial framework for its function.\",\n      \"evidence\": \"Transfection and subcellular localization in the original cloning study\",\n      \"pmids\": [\"9920784\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional activity linked to Golgi localization\", \"No effector or pathway identified\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected RAB36's Golgi localization to organelle positioning by showing overexpression clusters late endosomes/lysosomes perinuclearly and identifying RILP as a binding partner, defining a candidate retrograde transport role.\",\n      \"evidence\": \"EGFP-tagged WT/mutant expression, co-localization with organelle markers, GST pull-down\",\n      \"pmids\": [\"19961360\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Overexpression phenotype not validated by loss-of-function\", \"Binding region on RAB36 not mapped\", \"Motor machinery not identified\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"A Rab-wide interaction screen flagged GAPCenA/TBC1D11 as a RAB36 binding protein through a non-TBC domain, hinting at additional regulatory partners.\",\n      \"evidence\": \"GST pull-down of 60 mammalian Rabs with mass spectrometry\",\n      \"pmids\": [\"20070612\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single pull-down with no functional follow-up\", \"Physiological relevance of the interaction unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined the effector logic of RAB36 by mapping its binding to the RHD of RILP-family proteins and JIP3/JIP4 and demonstrating, via knockdown, that RAB36 is required for retrograde melanosome transport independent of RAB7.\",\n      \"evidence\": \"Binding screens, RHD mutagenesis, siRNA in melanocytes including Rab27A-KO cells, live-cell imaging\",\n      \"pmids\": [\"22740695\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct motor adaptor at the melanosome not yet defined\", \"GTP-dependence of effector engagement not biochemically dissected here\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified the off-switch for RAB36 by showing the Rab9A effector RUTBC2 acts as its GAP and reduces RAB36 membrane association, placing RAB36 in a Rab9A-coupled regulatory circuit.\",\n      \"evidence\": \"In vitro GAP assay against a Rab panel, co-localization, catalytically inactive R829A mutant in cells\",\n      \"pmids\": [\"22637480\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"GEF for RAB36 not identified\", \"In vivo significance of RUTBC2-mediated inactivation untested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Placed RAB36 in a RAB35→MICAL-L1 recruitment cascade at Arf6-positive recycling endosomes, showing it recruits JIP4 there and is required for neurite outgrowth, broadening its role beyond melanosomes.\",\n      \"evidence\": \"siRNA, live-cell imaging, epistasis in NGF-stimulated PC12 cells\",\n      \"pmids\": [\"25086062\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cargo transported in this pathway not defined\", \"Mechanism linking JIP4 recruitment to outgrowth unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Resolved a direct biochemical mechanism by which RAB36 activates the myosin-5a motor, showing it drives RILPL2 binding to the myosin-5a GTD to expose the melanophilin-binding site and stimulate motor activity.\",\n      \"evidence\": \"ATPase and single-molecule motility assays, GST pull-down, analytical ultracentrifugation\",\n      \"pmids\": [\"31175157\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular reconstitution of this activation on melanosomes not shown\", \"Integration with the retrograde (dynein) transport role unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Distinguished RAB36 from its paralog Rab34 in ciliogenesis, showing RAB36 is not required for the extracellular ciliogenesis pathway in MDCK cells.\",\n      \"evidence\": \"MDCK knockout cell lines and ciliogenesis assays\",\n      \"pmids\": [\"33989527\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result; role in intracellular ciliogenesis not directly tested for RAB36\", \"Other cell types not examined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined RAB36 as one of at least three redundant melanosomal cargo receptors for retrograde transport, with full inhibition only on combined depletion with melanoregulin and Rab44.\",\n      \"evidence\": \"Triple siRNA knockdown in Rab27A-deficient melan-ash cells, melanosome distribution assays\",\n      \"pmids\": [\"36126775\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of redundancy among the three receptors unresolved\", \"Single-cell-type evidence\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The activating GEF for RAB36 and how its dynein-driven retrograde role is coordinated with myosin-5a activation on the same melanosome remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No GEF identified in the corpus\", \"Coordination of opposing/cooperating motors mechanistically unresolved\", \"In vivo physiological phenotype not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0038024\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RILP\", \"RILPL1\", \"RILPL2\", \"JIP3\", \"JIP4\", \"RUTBC2\", \"MICAL-L1\", \"TBC1D11\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}