{"gene":"RAB6A","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":1994,"finding":"Rab6 controls intra-Golgi transport, specifically between cis/medial and late Golgi compartments. Overexpression of GTP-bound (Q72L) or wild-type Rab6 blocked transport between alpha-mannosidase II-positive and sialyl-transferase-positive Golgi compartments without affecting ER-to-cis/medial Golgi or TGN-to-plasma membrane steps.","method":"Transient overexpression of wild-type, GTP-bound (Q72L), and GDP-bound (T27N) Rab6 mutants in mouse L cells and HeLa cells; intracellular transport assays using secreted alkaline phosphatase (SEAP) and influenza hemagglutinin (HA) as markers","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal transport assays, multiple mutants, replicated in two cell lines","pmids":["7798313"],"is_preprint":false},{"year":1994,"finding":"Golgi apparatus localization of Rab6 requires geranylgeranylation (not farnesylation) and sequences in the N-terminal 71 amino acids including the effector domain. The C-terminal hypervariable domain is required to prevent prenylated/palmitoylated Rab6 from mislocalizing to the plasma membrane.","method":"Chimeric Ras-Rab proteins and Rab6 mutants with altered C-terminal lipid modifications expressed in mammalian cells; complementation of yeast ypt6 null mutants","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — mutagenesis with functional validation in multiple systems (mammalian cells and yeast complementation)","pmids":["8264642"],"is_preprint":false},{"year":1994,"finding":"Rab6 interaction with RabGDI requires the effector domain, loop3/beta3, and the hypervariable region; geranylgeranylation on CXC or CC motifs supports significantly better membrane extraction by RabGDI than farnesylation or palmitoylation. The effector domain is required for RabGDI binding but not for efficient processing by RabGGTase.","method":"In vitro membrane extraction assays with Rab6 mutants bearing various C-terminal lipid modifications; binding studies with recombinant proteins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with defined Rab6 mutants, multiple lipid modification variants tested","pmids":["8175798"],"is_preprint":false},{"year":1995,"finding":"The nucleotide-bound conformation of Rab6 determines its posttranslational geranylgeranylation: only the GDP-bound form is isoprenylated and becomes membrane-bound in insect cells, whereas the GTP-bound form is not modified.","method":"Expression of GDP- and GTP-conformation point mutants of Rab6 in insect cells; Triton X-114 partitioning and cell fractionation to assess membrane association","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro/cell-based assay with mutagenesis, single lab, single study","pmids":["8521955"],"is_preprint":false},{"year":1995,"finding":"Rab6 interacts with GDI beta (GDP-dissociation inhibitor beta isoform) in a GDP-dependent manner; GDI beta removes Rab6 from membranes. Rab6 also interacts with a novel, unidentified protein in its two-hybrid screen.","method":"Yeast two-hybrid screen using Rab6 as bait against mouse brain cDNA library; in vitro membrane extraction assay with recombinant GDI beta","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two-hybrid identification confirmed with in vitro membrane extraction assay, single lab","pmids":["7782346"],"is_preprint":false},{"year":1996,"finding":"Rab6 is required for transport between cis and medial Golgi cisternae in a reconstituted cell-free Golgi transport assay. Anti-Rab6 antibodies and Fab fragments, as well as dominant-negative Rab6(N126I), inhibit transport and membrane fusion at the cisternal level.","method":"Cell-free reconstituted Golgi transport assay; inhibition with polyclonal antibodies, Fab fragments, and dominant-negative Rab6 mutant protein","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with both antibody inhibition and dominant-negative protein; multiple inhibitory approaches converge","pmids":["8663167"],"is_preprint":false},{"year":1997,"finding":"GTP-bound forms of Rab6 (wild-type and Q72L mutant) cause redistribution of Golgi resident proteins (e.g., beta-1,4-galactosyltransferase) into the ER and allow sialylated O-glycan addition to an ER-retained protein, phenocopying brefeldin A. This effect requires intact microtubules. GDP-bound Rab6 (T27N) does not cause redistribution but inhibits basal O-glycosylation.","method":"Overexpression of Rab6 mutants in HeLa cells; immunofluorescence, subcellular fractionation, glycosylation assays; microtubule depolymerization with nocodazole","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal assays (morphology, biochemistry, glycosylation), replicated findings, microtubule dependency established","pmids":["9050864"],"is_preprint":false},{"year":1998,"finding":"Rab6 interacts in its GTP-bound form with Rabkinesin-6, a kinesin-like protein localized to the Golgi apparatus. The C-terminal domain of Rabkinesin-6 contains the Rab6-interacting domain. Overexpression of this C-terminal domain inhibits Rab6-GTP-dependent intracellular transport effects, identifying a molecular motor as an effector of Rab6.","method":"Yeast two-hybrid screen; co-immunoprecipitation; pulldown with GST-fusion proteins; dominant-negative overexpression assays in cells","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — two-hybrid confirmed by co-IP and pulldown, with functional validation by dominant-negative effector domain overexpression","pmids":["9438855"],"is_preprint":false},{"year":1999,"finding":"Rab6 regulates a COPI-independent Golgi-to-ER retrograde transport pathway. FP-Rab6-positive transport carriers specifically accumulate Shiga toxin B-fragment (STB) during Golgi-to-ER transport. Overexpression of GDP-bound Rab6(T27N) inhibits Shiga holotoxin toxicity without affecting STB transport to the Golgi or Golgi morphology. Rab6/STB transport carriers are excluded from COPI-dependent recycling markers.","method":"Live-cell fluorescence microscopy of FP-Rab6 fusion; microinjection of COPI-blocking antibodies; T7 vaccinia-driven overexpression of Rab6 T27N; toxicity assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — live imaging plus antibody microinjection plus dominant-negative overexpression, multiple orthogonal approaches in one study","pmids":["10562278"],"is_preprint":false},{"year":1999,"finding":"GAPCenA is a GTPase-activating protein (GAP) specifically active on Rab6 in vitro (and to lesser extent on Rab4 and Rab2). A minor pool of GAPCenA associates with the centrosome and forms complexes with cytosolic gamma-tubulin, suggesting a role in coordinating microtubule nucleation with Golgi dynamics.","method":"Identification by two-hybrid screen; in vitro GAP assay with recombinant proteins; immunofluorescence; cell fractionation; gamma-tubulin co-immunoprecipitation","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro GAP activity demonstrated with recombinant proteins, subcellular localization confirmed by fractionation and immunofluorescence","pmids":["10202141"],"is_preprint":false},{"year":1999,"finding":"Golgins golgin-230/245/256 and golgin-97 target to the Golgi through a conserved C-terminal domain that preferentially binds Rab6. Mutations abolishing Golgi targeting also abrogate Rab6 binding. This domain defines a conserved family of Rab6-interacting coiled-coil proteins (golgins) likely involved in Rab6-regulated membrane tethering.","method":"Protein blot binding assay; mutagenesis; Golgi targeting assays in cells; sequence analysis across species","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — protein blot binding plus mutagenesis and targeting assays, but no reciprocal co-IP or in-solution binding","pmids":["10209123"],"is_preprint":false},{"year":2000,"finding":"Rab6A and Rab6A' are generated by alternative splicing of the RAB6A gene, differing in only three amino acids flanking the PM3 GTP-binding domain. Rab6A Q72L overexpression induces redistribution of Golgi proteins to the ER (retrograde), but Rab6A' Q72L does not. Rab6A' does not interact with Rabkinesin-6 but does interact with GAPCenA; one amino acid at position 87 (T vs A) underlies these functional differences.","method":"Gene structure analysis; GTP-binding assays; HeLa cell overexpression; immunofluorescence; yeast two-hybrid interaction assays for effector binding","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple functional assays combined with mutagenesis identifying critical single amino acid difference; multiple orthogonal methods in one study","pmids":["11071909"],"is_preprint":false},{"year":2000,"finding":"Rab6-KIFL (Rab6-binding kinesin) was identified as a Rab6-interacting protein. Endogenous Rab6-KIFL localizes to the spindle midzone during anaphase and to the cleavage furrow/midbody during telophase. Microinjection of anti-Rab6-KIFL antibodies results in binucleate cells due to defective cleavage furrow formation, demonstrating a role for this Rab6 effector in cytokinesis.","method":"Yeast two-hybrid identification; immunofluorescence; microinjection of inhibitory antibodies; time-lapse microscopy","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — two-hybrid confirmed by localization studies, functional role established by antibody microinjection with time-lapse imaging showing cytokinesis defect","pmids":["11060022"],"is_preprint":false},{"year":2001,"finding":"Retrograde transport from early/recycling endosomes to the TGN requires the Rab6A' isoform (not Rab6A) along with specific SNARE complexes (syntaxin 6, syntaxin 16, Vti1a with VAMP3/cellubrevin and VAMP4). Rab6A has been previously implicated in Golgi-to-ER transport instead.","method":"Novel permeabilized cell transport assay; protein interaction studies; dominant-negative and antibody inhibition approaches","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional cell-free transport assay plus mechanistic pathway dissection with specific inhibitors and interaction studies","pmids":["11839770"],"is_preprint":false},{"year":2002,"finding":"Rab6 recruits the dynactin complex to Golgi membranes in a GTP-dependent and Rab6-specific manner. Other Golgi Rabs (tested) do not bind dynactin and cannot support its membrane recruitment, establishing Rab6 as a specificity factor for dynactin recruitment.","method":"Pulldown and co-immunoprecipitation assays with recombinant Rab proteins; Golgi membrane recruitment assays; comparison with other Golgi Rabs","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays plus Golgi membrane recruitment demonstrated with specificity shown by comparison to other Rabs","pmids":["12401177"],"is_preprint":false},{"year":2002,"finding":"Two novel Rab6-interacting proteins, Rab6IP2A and Rab6IP2B (splice variants), are recruited to Golgi membranes in a Rab6:GTP-dependent manner. Overexpression of the Rab6-binding domain of Rab6IP2 partly inhibits retrograde transport of Shiga toxin B-subunit from plasma membrane to Golgi.","method":"Yeast two-hybrid screen; co-immunoprecipitation; Golgi recruitment assays; Shiga toxin transport assays with Rab6-binding domain overexpression","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two-hybrid confirmed by Golgi recruitment assay plus functional transport inhibition, single lab","pmids":["11929610"],"is_preprint":false},{"year":2003,"finding":"Rab6 is in its GTP-bound conformation on the Golgi apparatus and on transport intermediates as demonstrated by GFP-tagged conformation-specific recombinant antibodies expressed intracellularly. The geometry of transport intermediates is modulated by Rab6 activity.","method":"Antibody phage display to generate GTP-conformation-specific Rab6 antibodies; GFP-tagging and intracellular expression for live-cell imaging; fixed-cell immunostaining","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — novel conformation sensor with GFP-tagging for live and fixed imaging; provides direct evidence of active Rab6 localization","pmids":["12738866"],"is_preprint":false},{"year":2004,"finding":"Both Rab6A and Rab6A' GTP-restricted mutants promote microtubule-dependent recycling of Golgi resident glycosylation enzymes to the ER with similar efficiency. Rab6-directed Golgi-to-ER recycling requires functional dynactin (inhibited by p50/dynamitin overexpression or C-terminal Bicaudal-D fragment). Reduced Rab6 via siRNA perturbs Golgi organization and delays Golgi-to-ER recycling.","method":"siRNA knockdown of individual Rab6 isoforms; overexpression of GTP-restricted mutants; p50/dynamitin dominant-negative overexpression; immunofluorescence","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — RNAi knockdown plus overexpression plus dynactin inhibition, multiple orthogonal approaches","pmids":["15483056"],"is_preprint":false},{"year":2004,"finding":"TMF/ARA160 is a Rab6-binding golgin that binds all three known Rab6 isoforms. Depletion of TMF by RNAi causes modest dispersal of Golgi membranes, suggesting a role in Golgi organization.","method":"Pulldown and binding assays between TMF and Rab6 isoforms; RNAi depletion with immunofluorescence analysis of Golgi morphology","journal":"BMC cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding confirmed plus RNAi functional assay, single lab, modest phenotype","pmids":["15128430"],"is_preprint":false},{"year":2006,"finding":"siRNA knockdown reveals that Rab6A' (but not Rab6A) is the major isoform regulating retrograde Shiga toxin transport and Golgi-associated protein recycling through the ER. Rab6A' is also required for cell cycle progression through mitosis; cells with impaired Rab6A' are blocked in metaphase with activated Mad2-spindle checkpoint. Ile62 is a key residue uncoupling Rab6A' functions in mitosis and retrograde trafficking.","method":"isoform-specific siRNA knockdown; Shiga toxin B-subunit transport assay; cell cycle analysis; mutagenesis of Ile62","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — isoform-specific RNAi with multiple functional readouts, mutagenesis identifying key residue, replicated across assays","pmids":["16536738"],"is_preprint":false},{"year":2006,"finding":"Rab6A' GTPase activity at kinetochores regulates inactivation of the Mad2-spindle checkpoint. Impaired Rab6A' function (by dominant-negative expression or GAPCenA depletion) blocks cells in metaphase with activated Mad2 checkpoint and retains p150(Glued) (dynactin subunit) at kinetochores, suggesting Rab6A' regulates dynein/dynactin dynamics at kinetochores during mitosis.","method":"Dominant-negative Rab6A' expression; GAPCenA siRNA depletion; immunofluorescence for Mad2 and p150(Glued) at kinetochores; cell cycle analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent perturbations (dominant-negative and GAP depletion) converge on same phenotype, with mechanistic endpoint at kinetochore dynactin","pmids":["16395330"],"is_preprint":false},{"year":2007,"finding":"Rab6 marks exocytotic vesicles and, together with kinesin-1, drives processive microtubule-based transport to the cell periphery. Rab6 directs targeting of secretory vesicles to plasma membrane sites enriched in the cortical protein ELKS. Although Rab6 is not essential for secretion, it controls the spatial organization of exocytosis.","method":"Live-cell imaging of GFP-Rab6; siRNA knockdown of Rab6 and kinesin-1; co-localization of vesicles with ELKS-positive cortical sites; secretion assays","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — live imaging plus RNAi with functional readouts, interaction with ELKS validated, multiple orthogonal methods","pmids":["17681140"],"is_preprint":false},{"year":2007,"finding":"R6IP1 (Rab6-interacting protein 1) links Rab6 and Rab11 function: R6IP1 binds both Rab6 (targeting it to Golgi) and Rab11A (GTP-bound). Overexpression of R6IP1 promotes Rab11A-Rab6 interaction (FRET/FLIM) and causes pericentriolar accumulation of Rab11-positive recycling endosomes. R6IP1 function is also required during metaphase and cytokinesis.","method":"Yeast two-hybrid; co-immunoprecipitation; FRET/FLIM live-cell imaging; siRNA depletion; immunofluorescence; cell cycle analysis","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple interaction methods including quantitative FRET/FLIM, plus RNAi functional studies; multiple orthogonal methods","pmids":["17725553"],"is_preprint":false},{"year":2007,"finding":"Rab6 depletion suppresses Golgi ribbon fragmentation/dispersal induced by ZW10/RINT-1 or COG complex inactivation (epistatic relationship). Dominant-negative Rab6 and C-terminal Bicaudal-D fragment (which interferes with dynactin/dynein) both suppress ZW10-knockdown-induced Golgi disruption. Rab6 therefore acts upstream in two separate retrograde tether-dependent Golgi trafficking pathways (ZW10/RINT-1 and COG).","method":"siRNA epistasis experiments; dominant-negative Rab6 expression; dominant-negative Bicaudal-D fragment; immunofluorescence; multiple Rab depletion combinations","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic genetic epistasis with multiple orthogonal perturbations, clear pathway placement","pmids":["17699596"],"is_preprint":false},{"year":2007,"finding":"TMF/ARA160 is functionally involved in two Rab6-dependent retrograde pathways: retrograde transport of Shiga toxin from endosomes to TGN, and retention of specific Golgi enzymes (GalNAc-T2 but not GalT) at the Golgi. TMF localizes to cisternal tips/budding structures at the Golgi as shown by immunoelectron microscopy.","method":"siRNA knockdown of TMF and Rab6; Shiga toxin transport assay; immunofluorescence; immunoelectron microscopy; chimeric protein domain swap experiments","journal":"Experimental cell research","confidence":"High","confidence_rationale":"Tier 2 / Strong — siRNA knockdown of both proteins with multiple functional readouts, ultrastructural localization by EM, domain swap experiments","pmids":["17698061"],"is_preprint":false},{"year":2008,"finding":"SCYL1BP1 (GORAB) localizes to the Golgi apparatus and interacts with Rab6, functioning as a golgin. Loss-of-function mutations in SCYL1BP1 cause gerodermia osteodysplastica, associating Rab6-dependent secretory pathway defects with age-related connective tissue changes.","method":"Identification of disease-causing mutations; subcellular localization studies; interaction assays between GORAB and Rab6","journal":"Nature genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — disease-associated loss-of-function mutations, localization confirmed, Rab6 interaction demonstrated, single study","pmids":["18997784"],"is_preprint":false},{"year":2008,"finding":"DYNLRB1 (dynein light chain) specifically interacts with all three Rab6 isoforms and co-localizes at the Golgi. DYNLRB1 shows preferred association with GTP-bound Rab6A but GDP-bound Rab6A' and Rab6B, representing the first direct interaction identified between Rab6 and the dynein complex.","method":"Yeast two-hybrid; co-immunoprecipitation; pulldown with GTP/GDP-loaded Rab6 isoforms; immunofluorescence co-localization","journal":"Cell motility and the cytoskeleton","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two-hybrid confirmed by co-IP and pulldown with nucleotide-state specificity, single lab","pmids":["18044744"],"is_preprint":false},{"year":2008,"finding":"Three Rab6a effectors (PIST, BicaudalD2, p150(Glued)) bind activated Rab6a through >15-kDa coiled-coil domains with Kd values in the high-nanomolar to low-micromolar range. BicaudalD2 and p150 binding moderately inhibits intrinsic Rab6a GTPase activity; PIST binding does not. Effectors bind in an apparent single-step reaction with relatively rapid on- and off-rates.","method":"In vitro biophysical binding assays (SPR, fluorescence); identification of minimal binding domains; GTPase activity assays with bound effectors","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — quantitative in vitro biophysical analysis with multiple effectors, kinetic and equilibrium constants determined, GTPase modulation measured","pmids":["19019823"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of Rab6a(GTP) in complex with a 378-residue fragment of Rab6IP1 (containing RUN and PLAT domains) solved at 3.2 Å. The first and last alpha-helices of the RUN domain mediate binding to switch I, switch II, and the interswitch region of Rab6. Comparison with Rab6-GCC185 complex reveals conformational flexibility in the conserved hydrophobic triad of Rab6 that enables recognition of compositionally distinct effectors.","method":"X-ray crystallography; structure determination at 3.2 Å resolution; structural comparison with Rab6-GCC185 complex","journal":"Structure (London, England : 1993)","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure determination with functional domain mapping; structural basis for Rab6 effector promiscuity revealed","pmids":["19141279"],"is_preprint":false},{"year":2010,"finding":"BICDR-1 (Bicaudal-D-related protein 1) is a Rab6 effector that interacts with kinesin Kif1C and the dynein/dynactin complex, and accumulates Rab6 secretory vesicles in the pericentrosomal region of young neurons, restricting anterograde secretory transport and inhibiting neuritogenesis. BICDR-1 expression declines during development, permitting later anterograde transport required for neurite outgrowth.","method":"Co-immunoprecipitation; live-cell imaging; siRNA knockdown; zebrafish morpholino neural development assay; vesicle motility measurements","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple interaction assays, live imaging, in vivo zebrafish validation, multiple orthogonal methods","pmids":["20360680"],"is_preprint":false},{"year":2010,"finding":"Rab33B and Rab6 act sequentially in an intra-Golgi retrograde trafficking Rab cascade: Rab6 acts downstream of Rab33B (overexpression of GTP-Rab33B induces dissociation of Rab6 from Golgi membranes). Efficient GTP-Rab6-induced relocation of Golgi enzymes to the ER is Rab33B-dependent, but not vice versa.","method":"siRNA epistasis experiments; overexpression of GTP-restricted Rab mutants; immunofluorescence; Golgi morphology analysis; Shiga toxin transport assay","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — systematic epistasis with multiple Rab perturbations establishing pathway order, multiple transport readouts","pmids":["20163571"],"is_preprint":false},{"year":2011,"finding":"Rab8A associates with exocytotic vesicles in a Rab6-dependent manner. Rab8A is required for docking and fusion (but not budding or motility) of exocytotic carriers. MICAL3 links Rab8A and ELKS at the cell cortex; MICAL3 monooxygenase activity is required for vesicle-docking complex remodeling and fusion. Rab6 and Rab8 thus cooperate sequentially in constitutive exocytosis.","method":"Live-cell imaging; siRNA knockdown of Rab6 and Rab8; co-immunoprecipitation; MICAL3 catalytic mutant expression; vesicle docking/fusion quantification","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple interaction assays, live imaging of vesicle behavior, mutagenesis of MICAL3 catalytic domain, multiple orthogonal methods","pmids":["21596566"],"is_preprint":false},{"year":2012,"finding":"The Ric1-Rgp1 complex is the guanine nucleotide exchange factor (GEF) for Rab6A in human cells. Both Ric1 and Rgp1 are required to catalyze nucleotide exchange on Rab6A and preferentially bind its GDP-bound form. Loss of Ric1 or Rgp1 destabilizes Rab6 and blocks retrograde transport of mannose-6-phosphate receptors to the Golgi. Rab33B-GTP binds the C-terminus of Ric1, establishing a Rab33B→Ric1/Rgp1→Rab6A cascade.","method":"In vitro nucleotide exchange assay with recombinant proteins; co-immunoprecipitation; siRNA knockdown; retrograde transport assay for mannose-6-phosphate receptors; domain-binding studies","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro GEF activity demonstrated with recombinant proteins, functional validation by RNAi, Rab cascade established","pmids":["23091056"],"is_preprint":false},{"year":2012,"finding":"Rab6 depletion causes accumulation of trans-Golgi clathrin-coated and COPI-coated vesicles and an increase of >50% in Golgi cisternae number. Rab6 is essential for trafficking of these two morphological classes of coated vesicles at the trans-Golgi.","method":"siRNA knockdown of Rab6; electron microscopy and electron tomography; quantitative morphometric analysis","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — unbiased high-resolution electron tomography with quantitative analysis in Rab6-depleted cells","pmids":["22335553"],"is_preprint":false},{"year":2013,"finding":"Rab6A/A' are required for post-Golgi trafficking of TNF from TGN-derived tubular carriers to the cell surface in LPS-activated macrophages. Rab6 localizes to p230-positive TGN tubular carriers, and its depletion reduces carrier egress and partially reduces p230 membrane association. Both Rab6 isoforms are needed for macrophage Golgi organization and efficient post-Golgi TNF transport.","method":"siRNA and shRNA depletion; dominant-negative mutants; live-cell imaging of Rab6-GFP on TGN tubular carriers; secretion assays; electron microscopy","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple depletion approaches, live imaging, EM, secretion assays; multiple orthogonal methods","pmids":["23437303"],"is_preprint":false},{"year":2014,"finding":"COH1 (VPS13B) Golgi localization depends on RAB6: RAB6A/A' knockdown prevents COH1 localization to the Golgi, constitutively inactive RAB6_T27N increases solubilization of COH1 from membranes, and constitutively active RAB6_Q72L preferentially co-immunoprecipitates with COH1. COH1 depletion in primary neurons impairs neurite outgrowth.","method":"siRNA knockdown; co-immunoprecipitation with RAB6 mutants; lipid membrane fractionation; neurite outgrowth assay in primary neurons","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple Rab6 mutant approaches plus co-IP, neuronal functional readout, multiple orthogonal methods","pmids":["25492866"],"is_preprint":false},{"year":2015,"finding":"KIF1C transports Rab6A vesicles and influences Golgi organization by binding Rab6A directly at both its motor domain and C-terminus. Rab6A binding to the KIF1C motor domain inhibits microtubule interaction in vitro and in cells. KIF1C depletion slows protein delivery to the cell surface, impairs vesicle motility, and causes Golgi fragmentation. KIF1C can protect Golgi from fragmentation independently of motor function when both Rab6A-binding sites are intact.","method":"In vitro microtubule interaction assay; pulldown; co-immunoprecipitation; siRNA knockdown; live-cell imaging; cargo delivery assay","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of motor-domain inhibition by Rab6A binding, combined with cell-based functional studies and mechanistic mutagenesis","pmids":["25821985"],"is_preprint":false},{"year":2015,"finding":"BICD2 stabilizes GTP-bound Rab6A on Golgi membranes: BICD2 knockdown reduces active Rab6A levels at the Golgi, and overexpression of C-terminal BICD2 decreases GFP-Rab6A exchange rate at Golgi (by FRAP). Rab6A and BICD2 jointly mediate COPI-independent Golgi-to-ER retrograde transport (Golgi tubule fusion with ER in BFA-treated cells).","method":"Golgi-targeting reconstitution in permeabilized cells; immunofluorescence; FRAP; siRNA knockdown; BFA-induced Golgi-to-ER transport assay","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 2 / Strong — reconstitution assay, FRAP, multiple functional transport assays; multiple orthogonal methods in one study","pmids":["25962623"],"is_preprint":false},{"year":2015,"finding":"GORAB missense mutations (p.Ala220Pro and p.Ser175Phe) in the IGRAB domain disrupt RAB6 binding and Golgi targeting of GORAB. ARF5 (GTP-bound) also binds the same IGRAB domain, and the p.Ala220Pro mutation abrogates both RAB6 and ARF5 binding while p.Ser175Phe selectively impairs ARF5 binding.","method":"Yeast two-hybrid screening; immunofluorescence; Brefeldin A treatment; mutagenesis; protein interaction assays","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus functional localization with mutagenesis, single lab","pmids":["26000619"],"is_preprint":false},{"year":2015,"finding":"RAB6A knockout mouse embryonic fibroblasts (MEFs) show altered Golgi morphology, decreased Golgi-associated levels of Rab6 effectors (Bicaudal-D and myosin II), delayed VSV-G secretion, and protection against ricin toxicity. RAB6A homozygous null mice die at early embryonic development, establishing RAB6A as an essential gene.","method":"Conditional RAB6A knockout using Cre-loxP/tamoxifen system; Western blot; immunofluorescence; secretion assays; ricin toxicity assays","journal":"Biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with multiple phenotypic readouts, in vivo lethality established, multiple assays","pmids":["26304202"],"is_preprint":false},{"year":2017,"finding":"In melanocytes, the RAB6/ELKS-dependent secretory pathway directly transports and docks Golgi-derived carriers (carrying MART-1 and TYRP2/DCT) to melanosomes, controlling melanosome formation, maturation, and pigment synthesis. RAB6 KO mice display pigmentation defects.","method":"Live-cell imaging; siRNA knockdown; RAB6 KO mouse model; cargo tracking; melanosome maturation assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — live imaging plus in vivo mouse KO plus cargo tracking, multiple orthogonal methods","pmids":["28607494"],"is_preprint":false},{"year":2018,"finding":"Rab6-dependent retrograde transport of LAT (linker for activation of T cells) through the Golgi-TGN is required for its polarized delivery to the immune synapse and for TCR-mediated T lymphocyte activation. This retrograde traffic also depends on Syntaxin-16. Rab6 KO CD4+ T lymphocytes show impaired TCR stimulation in vivo.","method":"siRNA knockdown of Rab6 and Syntaxin-16 in human cells; Rab6 KO mouse CD4+ T cells; LAT trafficking assays; immune synapse formation assays; TCR stimulation assays","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent perturbation approaches (siRNA and KO mouse), in vitro and in vivo validation, functional signaling readout","pmids":["29440364"],"is_preprint":false},{"year":2019,"finding":"RAB6 and microtubules restrict protein secretion to focal-adhesion-juxtaposed hotspots at the cell surface. Most post-Golgi carriers are RAB6-positive regardless of cargo, and RAB6 inactivation leads to broad reduction of protein secretion.","method":"Synchronized secretion assay (RUSH system); live-cell imaging; siRNA/dominant-negative Rab6 inactivation; colocalization with focal adhesion markers","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — synchronized secretion assay with live imaging, dominant-negative plus siRNA, multiple cargos tested","pmids":["31142554"],"is_preprint":false},{"year":2019,"finding":"Rab6 negatively regulates cell migration by interacting with Cdc42 and Trio (a GEF for Cdc42), thereby suppressing Cdc42 activity. Loss of Rab6 promotes actin protrusion formation and upregulates Cdc42 activity while downregulating myosin II phosphorylation.","method":"Rab6 KO/knockdown; Cdc42 GTPase activity assay; co-immunoprecipitation of Rab6 with Cdc42 and Trio; actin protrusion quantification; cell migration assays in vitro and in vivo","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus GTPase assay plus functional KO phenotype, single lab, multiple methods","pmids":["30830239"],"is_preprint":false},{"year":2020,"finding":"ELKS1 captures Rab6-positive Golgi-derived vesicular cargo at presynaptic nerve terminals via Golgin-like mechanisms. Knockout and rescue experiments establish that ELKS1 captures Rab6 cargo; the capturing mechanism can be transferred to mitochondria by mistargeting ELKS1 or Rab6.","method":"ELKS1 and Rab6 knockout and rescue experiments; live-cell imaging; mitochondria mistargeting experiments; presynaptic vesicle assays in neurons","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout plus rescue plus domain transfer experiment, multiple orthogonal approaches establishing mechanism","pmids":["32521280"],"is_preprint":false},{"year":2021,"finding":"Newly synthesized TrkB receptors traffic through the secretory pathway in Rab6-positive carriers and are directly delivered into the axon. The combined activity of kinesin-1 and kinesin-3 drives formation and anterograde transport of these TrkB/Rab6-positive secretory carriers beyond the proximal axon.","method":"Microfluidic compartmental devices; inducible secretion assay; live-cell imaging; siRNA/knockout of kinesin-1 and kinesin-3; Rab6 co-localization assays","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — inducible secretion assay plus live imaging plus kinesin knockouts, multiple orthogonal approaches","pmids":["33571451"],"is_preprint":false},{"year":2022,"finding":"Post-Golgi transport of RAB6+ vesicles in apical radial glia (aRG) cells occurs toward microtubule minus ends and depends on dynein and LIS1 (dynein activator). Double knockout of RAB6A/A' and RAB6B impairs apical localization of the apical determinant Crumbs3 (CRB3) and induces retraction of the apical process, leading to aRG delamination and ectopic division. These defects are phenocopied by LIS1 knockout.","method":"In situ subcellular live imaging; conditional RAB6 double knockout; LIS1 knockout; CRB3 localization assays; neuroepithelial integrity analysis","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic double knockout plus live imaging, epistatic validation with LIS1, in vivo relevance established","pmids":["35979738"],"is_preprint":false},{"year":1993,"finding":"A cytosolic complex of p62 and Rab6 associates with TGN38/41 and is required for budding of exocytic vesicles from the TGN. Immunodepletion or competing peptides targeting p62, Rab6, or TGN38/41 cytoplasmic domains completely inhibit vesicle budding in a cell-free system.","method":"Co-immunoprecipitation from cell extracts; cell-free vesicle budding assay; immunodepletion; competing peptide inhibition; sizing column and velocity sedimentation","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — cell-free reconstitution of vesicle budding with multiple inhibitory approaches (immunodepletion and competing peptides)","pmids":["8349729"],"is_preprint":false},{"year":1999,"finding":"Rab6 in Drosophila photoreceptors controls rhodopsin anterograde transport through the Golgi; GTPase-defective Rab6(Q71L) prevents maturation of rhodopsin beyond an immature 40-kDa form, depletes Rh1 and Rh3 levels, and causes retinal degeneration.","method":"Transgenic overexpression in Drosophila photoreceptors; Western blot analysis of rhodopsin forms; histological analysis; heat-shock rhodopsin pulse-chase","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo transgenic Drosophila model with multiple Rab6 mutants, rhodopsin maturation assay, histological validation","pmids":["9685396"],"is_preprint":false},{"year":2000,"finding":"In platelets, Rab6 is phosphorylated by protein kinase C (PKC) in a thrombin-stimulated manner. PKC phosphorylation of Rab6 increases GTP affinity ~3-fold, does not alter GTPase activity, and causes translocation of Rab6 from platelet particulate fractions to the cytosol.","method":"Metabolic [32P] labeling; PKC inhibitor (Ro-31-8220); cell fractionation; in vitro PKC phosphorylation of recombinant Rab6C; nucleotide binding affinity measurements","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro phosphorylation with recombinant protein plus in vivo labeling, quantitative binding measurements, specific inhibitor control","pmids":["10455022"],"is_preprint":false}],"current_model":"RAB6A is a Golgi-localized small GTPase (active GTP-bound form on Golgi and transport intermediates) that regulates multiple trafficking steps: (1) intra-Golgi retrograde transport involving coated vesicle trafficking at the trans-Golgi; (2) a COPI-independent, microtubule- and dynein/dynactin-dependent retrograde Golgi-to-ER pathway (primarily via Rab6A isoform); (3) retrograde endosome-to-TGN transport (primarily via Rab6A' isoform); (4) post-Golgi anterograde secretory vesicle transport to focal-adhesion hotspots at the plasma membrane, where it recruits kinesin-1 for processive microtubule-based movement and directs vesicle targeting via the cortical tether ELKS; (5) coordination of exocytic vesicle docking/fusion through sequential handoff to Rab8 via MICAL3; and (6) mitotic progression via regulation of dynein/dynactin dynamics at kinetochores. These activities are mediated by a diverse array of effectors recruited to GTP-Rab6, including Rabkinesin-6/KIF20A, KIF1C, dynactin (p150^Glued), DYNLRB1, BicaudalD/BICD2, BICDR-1, ELKS, TMF, Rab6IP1/2, GAPCenA (its cognate GAP), and Ric1-Rgp1 (its cognate GEF), with the Rab6A vs. Rab6A' isoforms (differing by only 3 amino acids from alternative splicing) performing non-overlapping functions due to differential effector binding."},"narrative":{"mechanistic_narrative":"RAB6A is a Golgi-localized small GTPase that serves as a master organizer of multiple membrane trafficking steps, switching between GDP- and GTP-bound states to recruit a diverse array of effectors to the Golgi and to transport carriers [PMID:7798313, PMID:12738866]. Its Golgi targeting requires geranylgeranylation and N-terminal sequences, with the nucleotide state governing both its prenylation and its membrane cycle through RabGDI extraction [PMID:8264642, PMID:8175798, PMID:8521955]; the Ric1-Rgp1 complex acts as its GEF and GAPCenA as its GAP, the latter being shared with the kinetochore-associated functions of the protein [PMID:23091056, PMID:10202141]. In its GTP-bound form RAB6 controls intra-Golgi retrograde transport and trafficking of trans-Golgi coated vesicles, and drives a COPI-independent, microtubule- and dynactin/dynein-dependent Golgi-to-ER retrograde pathway that recycles Golgi glycosylation enzymes [PMID:7798313, PMID:22335553, PMID:9050864, PMID:15483056]. RAB6 achieves these movements by recruiting cytoskeletal effectors—dynactin (p150Glued), the dynein light chain DYNLRB1, BICD2/BICDR-1, and the kinesins Rabkinesin-6/KIF20A and KIF1C—coupling carriers to bidirectional microtubule-based transport [PMID:12401177, PMID:18044744, PMID:19019823, PMID:20360680, PMID:25821985, PMID:9438855]. At the cell periphery RAB6 marks the majority of post-Golgi secretory carriers and, with kinesin-1, targets them to focal-adhesion-juxtaposed plasma-membrane hotspots defined by the cortical tether ELKS, where a sequential handoff to Rab8 via MICAL3 controls vesicle docking and fusion [PMID:17681140, PMID:31142554, PMID:21596566, PMID:32521280]. The gene encodes two splice isoforms, Rab6A and Rab6A', differing by three amino acids, that perform non-overlapping functions: Rab6A predominates in Golgi-to-ER recycling while Rab6A' governs endosome-to-TGN retrograde transport and mitotic progression by regulating dynein/dynactin and the Mad2 spindle checkpoint at kinetochores [PMID:11071909, PMID:11839770, PMID:16536738, PMID:16395330]. RAB6A is an essential gene whose loss is embryonic lethal in mice and whose secretory functions support pigmentation, T-cell receptor signaling, and neuronal development [PMID:26304202, PMID:28607494, PMID:29440364, PMID:35979738]. Loss-of-function mutations in the RAB6 effector GORAB cause gerodermia osteodysplastica, linking RAB6-dependent secretory trafficking to connective-tissue homeostasis [PMID:18997784].","teleology":[{"year":1993,"claim":"Established RAB6 as a component of the secretory machinery by showing a cytosolic p62-Rab6 complex required for budding of exocytic vesicles from the TGN.","evidence":"Cell-free vesicle budding assay with immunodepletion and competing peptides","pmids":["8349729"],"confidence":"High","gaps":["Did not define the GTPase cycle or effector logic","p62 identity and direct biochemical contacts not resolved"]},{"year":1994,"claim":"Placed RAB6 functionally at the intra-Golgi transport step and defined the membrane-targeting determinants and GDI-dependent membrane cycle, answering where and how the GTPase acts.","evidence":"Overexpression of GTP/GDP mutants with transport assays; chimeric prenylation mutants; yeast complementation; in vitro membrane extraction with RabGDI","pmids":["7798313","8264642","8175798"],"confidence":"High","gaps":["Effectors mediating transport not yet identified","Distinction between intra-Golgi and retrograde-to-ER roles not resolved"]},{"year":1995,"claim":"Showed that the nucleotide-bound conformation controls RAB6 prenylation and GDI-dependent extraction, linking the GTPase switch to the membrane attachment cycle.","evidence":"Conformational mutants in insect cells with Triton X-114 partitioning; two-hybrid plus membrane extraction with GDI beta","pmids":["8521955","7782346"],"confidence":"Medium","gaps":["Single-lab/single-study for prenylation-conformation coupling","Novel two-hybrid interactor left unidentified"]},{"year":1997,"claim":"Revealed a microtubule-dependent Golgi-to-ER retrograde route by showing GTP-RAB6 redistributes Golgi enzymes to the ER, separating retrograde recycling from forward secretion.","evidence":"Rab6 mutant overexpression in HeLa with glycosylation/fractionation readouts and nocodazole microtubule disruption","pmids":["9050864"],"confidence":"High","gaps":["Motor/tether machinery driving the route not yet defined","Relationship to COPI not yet established"]},{"year":1998,"claim":"Identified the first RAB6 motor effector, demonstrating that the GTPase couples membranes to microtubule motors via Rabkinesin-6.","evidence":"Two-hybrid, co-IP, GST pulldown, and dominant-negative effector-domain overexpression","pmids":["9438855"],"confidence":"High","gaps":["Directionality of motor transport not resolved","Did not address dynein-based retrograde movement"]},{"year":1999,"claim":"Defined the COPI-independent nature of RAB6 retrograde transport and identified its cognate GAP, while linking RAB6 effectors to membrane tethering golgins.","evidence":"Live imaging of FP-Rab6 carriers and Shiga toxin transport; COPI-antibody microinjection; in vitro GAP assay for GAPCenA; golgin protein-blot binding","pmids":["10562278","10202141","10209123"],"confidence":"High","gaps":["GEF still unknown at this stage","Golgin binding lacked reciprocal in-solution validation (idx 10)"]},{"year":2000,"claim":"Resolved that two splice isoforms differing by three amino acids carry distinct functions, and uncovered a mitotic role through the Rab6-binding kinesin in cytokinesis.","evidence":"Gene structure analysis, isoform overexpression with two-hybrid effector binding; Rab6-KIFL localization and inhibitory-antibody microinjection with time-lapse","pmids":["11071909","11060022"],"confidence":"High","gaps":["Mechanism coupling RAB6 to the cytokinetic apparatus incomplete","Single-residue determinant of isoform divergence functionally probed but structural basis unknown"]},{"year":2001,"claim":"Assigned endosome-to-TGN retrograde transport specifically to the Rab6A' isoform with defined SNARE partners, separating isoform functions in distinct trafficking routes.","evidence":"Permeabilized-cell transport assay with isoform-specific and SNARE inhibition","pmids":["11839770"],"confidence":"High","gaps":["Effectors specific to the Rab6A' endosome route not fully enumerated","Coordination with Golgi-to-ER route unresolved"]},{"year":2002,"claim":"Established RAB6 as the specificity factor recruiting dynactin to Golgi membranes and added new Golgi-recruited effectors, building the dynein/dynactin-based retrograde transport model.","evidence":"Pulldown/co-IP with recombinant Rabs and Golgi recruitment assays; two-hybrid plus recruitment for Rab6IP2A/B with Shiga toxin readout","pmids":["12401177","11929610"],"confidence":"High","gaps":["Direct vs. adaptor-mediated dynactin contact not fully resolved","Rab6IP2 confirmed by single lab only"]},{"year":2003,"claim":"Provided direct evidence that active GTP-RAB6 resides on the Golgi and transport intermediates and shapes carrier geometry, validating the GTPase as conformationally active in situ.","evidence":"Conformation-specific intrabodies (GFP-tagged) for live and fixed imaging","pmids":["12738866"],"confidence":"High","gaps":["Spatial regulation of GTP/GDP cycling on carriers not mapped","GEF/GAP localization relative to active pool not defined"]},{"year":2004,"claim":"Confirmed both isoforms drive dynactin-dependent Golgi-to-ER recycling and demonstrated by RNAi that RAB6 organizes the Golgi, integrating loss-of-function with overexpression evidence.","evidence":"Isoform-specific siRNA, GTP-mutant overexpression, dynamitin/Bicaudal-D dominant-negatives, immunofluorescence","pmids":["15483056"],"confidence":"High","gaps":["Quantitative isoform contribution to recycling not separated here","Did not address mitotic functions"]},{"year":2006,"claim":"Dissected Rab6A' as the dominant retrograde isoform and uncovered a kinetochore function in inactivating the Mad2 checkpoint via dynein/dynactin dynamics, uncoupling trafficking and mitotic roles.","evidence":"Isoform-specific siRNA with Shiga toxin and cell-cycle readouts; dominant-negative and GAPCenA depletion with Mad2/p150Glued kinetochore staining; Ile62 mutagenesis","pmids":["16536738","16395330"],"confidence":"High","gaps":["How a Golgi GTPase localizes activity to kinetochores not mechanistically resolved","GEF for the kinetochore pool unidentified"]},{"year":2007,"claim":"Defined RAB6's exocytic targeting role, its epistatic position upstream of retrograde tether complexes, and effector links bridging RAB6 to Rab11 and golgin TMF.","evidence":"Live imaging and siRNA for Rab6/kinesin-1 with ELKS colocalization; siRNA epistasis with ZW10/RINT-1 and COG; two-hybrid/FRET-FLIM for R6IP1; TMF binding and RNAi with immuno-EM","pmids":["17681140","17699596","17725553","17698061"],"confidence":"High","gaps":["Mechanism by which ELKS captures carriers not yet defined","TMF and R6IP2 functional details confined to single labs"]},{"year":2008,"claim":"Provided quantitative biophysical parameters for effector binding, identified a dynein light chain partner, and linked RAB6 effector GORAB to human disease.","evidence":"SPR/fluorescence binding kinetics and GTPase modulation for PIST/BICD2/p150; two-hybrid/co-IP/pulldown for DYNLRB1; GORAB disease-mutation and interaction studies","pmids":["19019823","18044744","18997784"],"confidence":"High","gaps":["DYNLRB1 nucleotide-state preferences differ across isoforms without structural explanation","GORAB mechanism in disease pathology not detailed (Medium)"]},{"year":2009,"claim":"Provided the structural basis for RAB6 effector promiscuity by solving the Rab6a(GTP)-Rab6IP1 complex and revealing conformational flexibility in its hydrophobic triad.","evidence":"X-ray crystallography at 3.2 Å with comparison to Rab6-GCC185","pmids":["19141279"],"confidence":"High","gaps":["Structures of motor- and tether-effector complexes not solved","Isoform-specific structural differences not captured"]},{"year":2010,"claim":"Embedded RAB6 in a Rab33B->Rab6 retrograde cascade and identified BICDR-1 as a developmentally regulated effector restraining anterograde secretory transport in neurons.","evidence":"siRNA epistasis with GTP-Rab33B; co-IP, live imaging, siRNA, and zebrafish morpholino for BICDR-1/Kif1C","pmids":["20163571","20360680"],"confidence":"High","gaps":["GEF connecting Rab33B to Rab6 not yet identified at this stage","Developmental switch controlling BICDR-1 levels not mechanistically defined"]},{"year":2011,"claim":"Defined a sequential RAB6-to-Rab8 handoff for exocytosis, showing RAB6 recruits Rab8 to carriers and MICAL3 monooxygenase activity remodels docking complexes for fusion.","evidence":"Live imaging, siRNA of Rab6/Rab8, co-IP, and MICAL3 catalytic-mutant expression with docking/fusion quantification","pmids":["21596566"],"confidence":"High","gaps":["Molecular trigger for the Rab6-to-Rab8 conversion not defined","MICAL3 substrate during remodeling not identified"]},{"year":2012,"claim":"Identified the Ric1-Rgp1 GEF completing the RAB6 regulatory cycle and closing the Rab33B->Ric1/Rgp1->Rab6 cascade, and resolved the coated-vesicle defects of RAB6 loss ultrastructurally.","evidence":"In vitro nucleotide exchange with recombinant proteins, co-IP, siRNA with M6PR transport assay; electron tomography of Rab6-depleted Golgi","pmids":["23091056","22335553"],"confidence":"High","gaps":["Spatial regulation of GEF activation on Golgi not mapped","Whether the cascade applies to all RAB6 routes unresolved"]},{"year":2013,"claim":"Extended RAB6's post-Golgi secretory role to immune effector output by showing both isoforms are needed for TGN-to-surface TNF carrier egress in activated macrophages.","evidence":"siRNA/shRNA depletion, dominant-negative mutants, live imaging of TGN carriers, secretion assays, EM","pmids":["23437303"],"confidence":"High","gaps":["Cargo-selectivity of RAB6 carriers not addressed","Link to inflammatory signaling pathways not explored"]},{"year":2014,"claim":"Identified VPS13B/COH1 as a RAB6-dependent Golgi-recruited factor required for neurite outgrowth, broadening RAB6's role in neuronal membrane organization.","evidence":"siRNA, co-IP with Rab6 mutants, membrane fractionation, neurite outgrowth in primary neurons","pmids":["25492866"],"confidence":"High","gaps":["Trafficking step served by COH1 not precisely defined","Direct vs. indirect RAB6-COH1 contact not fully resolved"]},{"year":2015,"claim":"Defined motor- and adaptor-level mechanisms—KIF1C autoinhibition by RAB6A binding and BICD2 stabilization of active RAB6—and refined GORAB disease mechanism, sharpening the transport machinery model.","evidence":"In vitro microtubule assays and cell studies for KIF1C; FRAP/reconstitution for BICD2; two-hybrid/mutagenesis for GORAB-RAB6/ARF5; RAB6A knockout MEFs with secretion and ricin assays plus embryonic lethality","pmids":["25821985","25962623","26000619","26304202"],"confidence":"High","gaps":["How motor autoinhibition is relieved on carriers not resolved","GORAB-ARF5 binding interface in disease confirmed in single lab (Medium)"]},{"year":2017,"claim":"Demonstrated a physiological RAB6/ELKS secretory pathway delivering melanogenic cargo to melanosomes, with pigmentation defects in RAB6 KO mice establishing in vivo relevance.","evidence":"Live imaging, siRNA, RAB6 KO mouse, cargo tracking, melanosome maturation assays","pmids":["28607494"],"confidence":"High","gaps":["Selectivity of RAB6 carriers for melanosomal cargo not mechanistically defined","Role of isoforms in melanocytes not separated"]},{"year":2018,"claim":"Connected RAB6 retrograde trafficking to adaptive immunity by showing RAB6/Syntaxin-16-dependent LAT recycling is required for immune synapse delivery and TCR signaling.","evidence":"siRNA in human cells, RAB6 KO mouse CD4+ T cells, LAT trafficking and TCR stimulation assays","pmids":["29440364"],"confidence":"High","gaps":["How retrograde LAT routing achieves polarized synapse delivery not fully resolved","Effector mediating LAT capture not identified"]},{"year":2019,"claim":"Showed RAB6 spatially confines secretion to focal-adhesion-juxtaposed hotspots and uncovered an additional role in suppressing Cdc42 to restrain cell migration, broadening RAB6 beyond canonical secretion.","evidence":"RUSH synchronized secretion with live imaging and Rab6 inactivation; Cdc42 GTPase assay, co-IP with Cdc42/Trio, migration assays","pmids":["31142554","30830239"],"confidence":"High","gaps":["Mechanistic coupling of secretion hotspots to focal adhesions not defined","Rab6-Cdc42/Trio interaction confirmed in single lab (Medium)"]},{"year":2020,"claim":"Established the molecular logic of carrier capture by showing ELKS1 tethers RAB6 cargo at presynaptic terminals through golgin-like mechanisms transferable to ectopic organelles.","evidence":"ELKS1 and Rab6 knockout/rescue, live imaging, mitochondria mistargeting experiments in neurons","pmids":["32521280"],"confidence":"High","gaps":["Identity of the direct ELKS1-RAB6 tethering contact not defined","Generality across cell types beyond neurons not established"]},{"year":2021,"claim":"Showed RAB6-positive carriers deliver newly synthesized TrkB receptors into axons via combined kinesin-1/kinesin-3 activity, defining a directional anterograde transport mechanism in neurons.","evidence":"Microfluidic compartmental secretion assay, live imaging, kinesin-1/kinesin-3 knockdown/knockout, Rab6 colocalization","pmids":["33571451"],"confidence":"High","gaps":["How motor handoff is regulated along the axon not resolved","Cargo-specificity of RAB6 axonal carriers not defined"]},{"year":2022,"claim":"Demonstrated RAB6 carriers move toward microtubule minus ends via dynein/LIS1 in apical radial glia to deliver apical determinants, linking RAB6 trafficking to neuroepithelial integrity in vivo.","evidence":"In situ live imaging, conditional RAB6 double knockout, LIS1 knockout, CRB3 localization, neuroepithelial integrity analysis","pmids":["35979738"],"confidence":"High","gaps":["Switch between minus-end (dynein) and plus-end (kinesin) carrier transport not mechanistically resolved","Direct vs. effector-mediated dynein/LIS1 coupling not defined here"]},{"year":null,"claim":"How RAB6 selects among its many competing effectors and trafficking routes in space and time, and what governs the directional switch between dynein-driven retrograde and kinesin-driven anterograde transport on individual carriers, remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No model integrates effector competition with carrier-specific motor selection","Spatial control of GEF/GAP activation on distinct membrane domains not mapped","Isoform-specific effector code not fully enumerated structurally"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[9,27,32,16]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[14,21,31,37]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,1,16,33]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[8,16,21,42]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4,47,49]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[6,14,36,46]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,8,13,42]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[21,31,33,47]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[12,19,20]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[29,45,46,40]}],"complexes":[],"partners":["KIF20A","KIF1C","BICD2","DCTN1","DYNLRB1","ELKS","TMF","GORAB"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P20340","full_name":"Ras-related protein Rab-6A","aliases":[],"length_aa":208,"mass_kda":23.6,"function":"The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes (PubMed:25962623). 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 (PubMed:25962623). RAB6A acts as a regulator of COPI-independent retrograde transport from the Golgi apparatus towards the endoplasmic reticulum (ER) (PubMed:25962623). Has a low GTPase activity (PubMed:25962623). Recruits VPS13B to the Golgi membrane (PubMed:25492866). Plays a role in neuron projection development (Probable)","subcellular_location":"Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/P20340/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RAB6A","classification":"Not Classified","n_dependent_lines":607,"n_total_lines":1208,"dependency_fraction":0.5024834437086093},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"GDI1","stoichiometry":4.0},{"gene":"GDI2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/RAB6A","total_profiled":1310},"omim":[{"mim_id":"618761","title":"CATIFA SYNDROME; CATIFA","url":"https://www.omim.org/entry/618761"},{"mim_id":"617278","title":"DENN DOMAIN-CONTAINING PROTEIN 5A; DENND5A","url":"https://www.omim.org/entry/617278"},{"mim_id":"617002","title":"BICD FAMILY-LIKE CARGO ADAPTOR 1; BICDL1","url":"https://www.omim.org/entry/617002"},{"mim_id":"615852","title":"RAS-ASSOCIATED PROTEIN RAB6B; RAB6B","url":"https://www.omim.org/entry/615852"},{"mim_id":"615850","title":"VPS53 SUBUNIT OF GARP COMPLEX; VPS53","url":"https://www.omim.org/entry/615850"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RAB6A"},"hgnc":{"alias_symbol":[],"prev_symbol":["RAB6"]},"alphafold":{"accession":"P20340","domains":[{"cath_id":"3.40.50.300","chopping":"12-172","consensus_level":"high","plddt":95.4598,"start":12,"end":172}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P20340","model_url":"https://alphafold.ebi.ac.uk/files/AF-P20340-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P20340-F1-predicted_aligned_error_v6.png","plddt_mean":85.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RAB6A","jax_strain_url":"https://www.jax.org/strain/search?query=RAB6A"},"sequence":{"accession":"P20340","fasta_url":"https://rest.uniprot.org/uniprotkb/P20340.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P20340/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P20340"}},"corpus_meta":[{"pmid":"11839770","id":"PMC_11839770","title":"Early/recycling endosomes-to-TGN transport involves two SNARE complexes and a Rab6 isoform.","date":"2002","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11839770","citation_count":446,"is_preprint":false},{"pmid":"9438855","id":"PMC_9438855","title":"Interaction of a Golgi-associated kinesin-like protein with Rab6.","date":"1998","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/9438855","citation_count":425,"is_preprint":false},{"pmid":"10562278","id":"PMC_10562278","title":"Rab6 coordinates a novel Golgi to ER retrograde transport pathway in live cells.","date":"1999","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/10562278","citation_count":345,"is_preprint":false},{"pmid":"17681140","id":"PMC_17681140","title":"Rab6 regulates transport and targeting of exocytotic carriers.","date":"2007","source":"Developmental 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Methods & clinical development","url":"https://pubmed.ncbi.nlm.nih.gov/29707603","citation_count":16,"is_preprint":false},{"pmid":"16473625","id":"PMC_16473625","title":"Assay and functional properties of Rabkinesin-6/Rab6-KIFL/MKlp2 in cytokinesis.","date":"2005","source":"Methods in enzymology","url":"https://pubmed.ncbi.nlm.nih.gov/16473625","citation_count":16,"is_preprint":false},{"pmid":"28448737","id":"PMC_28448737","title":"Involvement of ARHGEF10, GEF for RhoA, in Rab6/Rab8-mediating membrane traffic.","date":"2017","source":"Small GTPases","url":"https://pubmed.ncbi.nlm.nih.gov/28448737","citation_count":15,"is_preprint":false},{"pmid":"30830239","id":"PMC_30830239","title":"Rab6 regulates cell migration and invasion by recruiting Cdc42 and modulating its activity.","date":"2019","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/30830239","citation_count":15,"is_preprint":false},{"pmid":"8521955","id":"PMC_8521955","title":"Nucleotide induced conformation determines posttranslational isoprenylation of the ras related rab6 protein in insect cells.","date":"1995","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/8521955","citation_count":15,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":46020,"output_tokens":13147,"usd":0.167632,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":24488,"output_tokens":8077,"usd":0.162183,"stage2_stop_reason":"end_turn"},"total_usd":0.329815,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"Rab6 controls intra-Golgi transport, specifically between cis/medial and late Golgi compartments. Overexpression of GTP-bound (Q72L) or wild-type Rab6 blocked transport between alpha-mannosidase II-positive and sialyl-transferase-positive Golgi compartments without affecting ER-to-cis/medial Golgi or TGN-to-plasma membrane steps.\",\n      \"method\": \"Transient overexpression of wild-type, GTP-bound (Q72L), and GDP-bound (T27N) Rab6 mutants in mouse L cells and HeLa cells; intracellular transport assays using secreted alkaline phosphatase (SEAP) and influenza hemagglutinin (HA) as markers\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal transport assays, multiple mutants, replicated in two cell lines\",\n      \"pmids\": [\"7798313\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Golgi apparatus localization of Rab6 requires geranylgeranylation (not farnesylation) and sequences in the N-terminal 71 amino acids including the effector domain. The C-terminal hypervariable domain is required to prevent prenylated/palmitoylated Rab6 from mislocalizing to the plasma membrane.\",\n      \"method\": \"Chimeric Ras-Rab proteins and Rab6 mutants with altered C-terminal lipid modifications expressed in mammalian cells; complementation of yeast ypt6 null mutants\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mutagenesis with functional validation in multiple systems (mammalian cells and yeast complementation)\",\n      \"pmids\": [\"8264642\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Rab6 interaction with RabGDI requires the effector domain, loop3/beta3, and the hypervariable region; geranylgeranylation on CXC or CC motifs supports significantly better membrane extraction by RabGDI than farnesylation or palmitoylation. The effector domain is required for RabGDI binding but not for efficient processing by RabGGTase.\",\n      \"method\": \"In vitro membrane extraction assays with Rab6 mutants bearing various C-terminal lipid modifications; binding studies with recombinant proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with defined Rab6 mutants, multiple lipid modification variants tested\",\n      \"pmids\": [\"8175798\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"The nucleotide-bound conformation of Rab6 determines its posttranslational geranylgeranylation: only the GDP-bound form is isoprenylated and becomes membrane-bound in insect cells, whereas the GTP-bound form is not modified.\",\n      \"method\": \"Expression of GDP- and GTP-conformation point mutants of Rab6 in insect cells; Triton X-114 partitioning and cell fractionation to assess membrane association\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro/cell-based assay with mutagenesis, single lab, single study\",\n      \"pmids\": [\"8521955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Rab6 interacts with GDI beta (GDP-dissociation inhibitor beta isoform) in a GDP-dependent manner; GDI beta removes Rab6 from membranes. Rab6 also interacts with a novel, unidentified protein in its two-hybrid screen.\",\n      \"method\": \"Yeast two-hybrid screen using Rab6 as bait against mouse brain cDNA library; in vitro membrane extraction assay with recombinant GDI beta\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two-hybrid identification confirmed with in vitro membrane extraction assay, single lab\",\n      \"pmids\": [\"7782346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Rab6 is required for transport between cis and medial Golgi cisternae in a reconstituted cell-free Golgi transport assay. Anti-Rab6 antibodies and Fab fragments, as well as dominant-negative Rab6(N126I), inhibit transport and membrane fusion at the cisternal level.\",\n      \"method\": \"Cell-free reconstituted Golgi transport assay; inhibition with polyclonal antibodies, Fab fragments, and dominant-negative Rab6 mutant protein\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with both antibody inhibition and dominant-negative protein; multiple inhibitory approaches converge\",\n      \"pmids\": [\"8663167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"GTP-bound forms of Rab6 (wild-type and Q72L mutant) cause redistribution of Golgi resident proteins (e.g., beta-1,4-galactosyltransferase) into the ER and allow sialylated O-glycan addition to an ER-retained protein, phenocopying brefeldin A. This effect requires intact microtubules. GDP-bound Rab6 (T27N) does not cause redistribution but inhibits basal O-glycosylation.\",\n      \"method\": \"Overexpression of Rab6 mutants in HeLa cells; immunofluorescence, subcellular fractionation, glycosylation assays; microtubule depolymerization with nocodazole\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal assays (morphology, biochemistry, glycosylation), replicated findings, microtubule dependency established\",\n      \"pmids\": [\"9050864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Rab6 interacts in its GTP-bound form with Rabkinesin-6, a kinesin-like protein localized to the Golgi apparatus. The C-terminal domain of Rabkinesin-6 contains the Rab6-interacting domain. Overexpression of this C-terminal domain inhibits Rab6-GTP-dependent intracellular transport effects, identifying a molecular motor as an effector of Rab6.\",\n      \"method\": \"Yeast two-hybrid screen; co-immunoprecipitation; pulldown with GST-fusion proteins; dominant-negative overexpression assays in cells\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two-hybrid confirmed by co-IP and pulldown, with functional validation by dominant-negative effector domain overexpression\",\n      \"pmids\": [\"9438855\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Rab6 regulates a COPI-independent Golgi-to-ER retrograde transport pathway. FP-Rab6-positive transport carriers specifically accumulate Shiga toxin B-fragment (STB) during Golgi-to-ER transport. Overexpression of GDP-bound Rab6(T27N) inhibits Shiga holotoxin toxicity without affecting STB transport to the Golgi or Golgi morphology. Rab6/STB transport carriers are excluded from COPI-dependent recycling markers.\",\n      \"method\": \"Live-cell fluorescence microscopy of FP-Rab6 fusion; microinjection of COPI-blocking antibodies; T7 vaccinia-driven overexpression of Rab6 T27N; toxicity assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live imaging plus antibody microinjection plus dominant-negative overexpression, multiple orthogonal approaches in one study\",\n      \"pmids\": [\"10562278\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"GAPCenA is a GTPase-activating protein (GAP) specifically active on Rab6 in vitro (and to lesser extent on Rab4 and Rab2). A minor pool of GAPCenA associates with the centrosome and forms complexes with cytosolic gamma-tubulin, suggesting a role in coordinating microtubule nucleation with Golgi dynamics.\",\n      \"method\": \"Identification by two-hybrid screen; in vitro GAP assay with recombinant proteins; immunofluorescence; cell fractionation; gamma-tubulin co-immunoprecipitation\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro GAP activity demonstrated with recombinant proteins, subcellular localization confirmed by fractionation and immunofluorescence\",\n      \"pmids\": [\"10202141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Golgins golgin-230/245/256 and golgin-97 target to the Golgi through a conserved C-terminal domain that preferentially binds Rab6. Mutations abolishing Golgi targeting also abrogate Rab6 binding. This domain defines a conserved family of Rab6-interacting coiled-coil proteins (golgins) likely involved in Rab6-regulated membrane tethering.\",\n      \"method\": \"Protein blot binding assay; mutagenesis; Golgi targeting assays in cells; sequence analysis across species\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — protein blot binding plus mutagenesis and targeting assays, but no reciprocal co-IP or in-solution binding\",\n      \"pmids\": [\"10209123\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Rab6A and Rab6A' are generated by alternative splicing of the RAB6A gene, differing in only three amino acids flanking the PM3 GTP-binding domain. Rab6A Q72L overexpression induces redistribution of Golgi proteins to the ER (retrograde), but Rab6A' Q72L does not. Rab6A' does not interact with Rabkinesin-6 but does interact with GAPCenA; one amino acid at position 87 (T vs A) underlies these functional differences.\",\n      \"method\": \"Gene structure analysis; GTP-binding assays; HeLa cell overexpression; immunofluorescence; yeast two-hybrid interaction assays for effector binding\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple functional assays combined with mutagenesis identifying critical single amino acid difference; multiple orthogonal methods in one study\",\n      \"pmids\": [\"11071909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Rab6-KIFL (Rab6-binding kinesin) was identified as a Rab6-interacting protein. Endogenous Rab6-KIFL localizes to the spindle midzone during anaphase and to the cleavage furrow/midbody during telophase. Microinjection of anti-Rab6-KIFL antibodies results in binucleate cells due to defective cleavage furrow formation, demonstrating a role for this Rab6 effector in cytokinesis.\",\n      \"method\": \"Yeast two-hybrid identification; immunofluorescence; microinjection of inhibitory antibodies; time-lapse microscopy\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two-hybrid confirmed by localization studies, functional role established by antibody microinjection with time-lapse imaging showing cytokinesis defect\",\n      \"pmids\": [\"11060022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Retrograde transport from early/recycling endosomes to the TGN requires the Rab6A' isoform (not Rab6A) along with specific SNARE complexes (syntaxin 6, syntaxin 16, Vti1a with VAMP3/cellubrevin and VAMP4). Rab6A has been previously implicated in Golgi-to-ER transport instead.\",\n      \"method\": \"Novel permeabilized cell transport assay; protein interaction studies; dominant-negative and antibody inhibition approaches\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional cell-free transport assay plus mechanistic pathway dissection with specific inhibitors and interaction studies\",\n      \"pmids\": [\"11839770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Rab6 recruits the dynactin complex to Golgi membranes in a GTP-dependent and Rab6-specific manner. Other Golgi Rabs (tested) do not bind dynactin and cannot support its membrane recruitment, establishing Rab6 as a specificity factor for dynactin recruitment.\",\n      \"method\": \"Pulldown and co-immunoprecipitation assays with recombinant Rab proteins; Golgi membrane recruitment assays; comparison with other Golgi Rabs\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays plus Golgi membrane recruitment demonstrated with specificity shown by comparison to other Rabs\",\n      \"pmids\": [\"12401177\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Two novel Rab6-interacting proteins, Rab6IP2A and Rab6IP2B (splice variants), are recruited to Golgi membranes in a Rab6:GTP-dependent manner. Overexpression of the Rab6-binding domain of Rab6IP2 partly inhibits retrograde transport of Shiga toxin B-subunit from plasma membrane to Golgi.\",\n      \"method\": \"Yeast two-hybrid screen; co-immunoprecipitation; Golgi recruitment assays; Shiga toxin transport assays with Rab6-binding domain overexpression\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two-hybrid confirmed by Golgi recruitment assay plus functional transport inhibition, single lab\",\n      \"pmids\": [\"11929610\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Rab6 is in its GTP-bound conformation on the Golgi apparatus and on transport intermediates as demonstrated by GFP-tagged conformation-specific recombinant antibodies expressed intracellularly. The geometry of transport intermediates is modulated by Rab6 activity.\",\n      \"method\": \"Antibody phage display to generate GTP-conformation-specific Rab6 antibodies; GFP-tagging and intracellular expression for live-cell imaging; fixed-cell immunostaining\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — novel conformation sensor with GFP-tagging for live and fixed imaging; provides direct evidence of active Rab6 localization\",\n      \"pmids\": [\"12738866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Both Rab6A and Rab6A' GTP-restricted mutants promote microtubule-dependent recycling of Golgi resident glycosylation enzymes to the ER with similar efficiency. Rab6-directed Golgi-to-ER recycling requires functional dynactin (inhibited by p50/dynamitin overexpression or C-terminal Bicaudal-D fragment). Reduced Rab6 via siRNA perturbs Golgi organization and delays Golgi-to-ER recycling.\",\n      \"method\": \"siRNA knockdown of individual Rab6 isoforms; overexpression of GTP-restricted mutants; p50/dynamitin dominant-negative overexpression; immunofluorescence\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — RNAi knockdown plus overexpression plus dynactin inhibition, multiple orthogonal approaches\",\n      \"pmids\": [\"15483056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TMF/ARA160 is a Rab6-binding golgin that binds all three known Rab6 isoforms. Depletion of TMF by RNAi causes modest dispersal of Golgi membranes, suggesting a role in Golgi organization.\",\n      \"method\": \"Pulldown and binding assays between TMF and Rab6 isoforms; RNAi depletion with immunofluorescence analysis of Golgi morphology\",\n      \"journal\": \"BMC cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding confirmed plus RNAi functional assay, single lab, modest phenotype\",\n      \"pmids\": [\"15128430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"siRNA knockdown reveals that Rab6A' (but not Rab6A) is the major isoform regulating retrograde Shiga toxin transport and Golgi-associated protein recycling through the ER. Rab6A' is also required for cell cycle progression through mitosis; cells with impaired Rab6A' are blocked in metaphase with activated Mad2-spindle checkpoint. Ile62 is a key residue uncoupling Rab6A' functions in mitosis and retrograde trafficking.\",\n      \"method\": \"isoform-specific siRNA knockdown; Shiga toxin B-subunit transport assay; cell cycle analysis; mutagenesis of Ile62\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — isoform-specific RNAi with multiple functional readouts, mutagenesis identifying key residue, replicated across assays\",\n      \"pmids\": [\"16536738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Rab6A' GTPase activity at kinetochores regulates inactivation of the Mad2-spindle checkpoint. Impaired Rab6A' function (by dominant-negative expression or GAPCenA depletion) blocks cells in metaphase with activated Mad2 checkpoint and retains p150(Glued) (dynactin subunit) at kinetochores, suggesting Rab6A' regulates dynein/dynactin dynamics at kinetochores during mitosis.\",\n      \"method\": \"Dominant-negative Rab6A' expression; GAPCenA siRNA depletion; immunofluorescence for Mad2 and p150(Glued) at kinetochores; cell cycle analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent perturbations (dominant-negative and GAP depletion) converge on same phenotype, with mechanistic endpoint at kinetochore dynactin\",\n      \"pmids\": [\"16395330\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Rab6 marks exocytotic vesicles and, together with kinesin-1, drives processive microtubule-based transport to the cell periphery. Rab6 directs targeting of secretory vesicles to plasma membrane sites enriched in the cortical protein ELKS. Although Rab6 is not essential for secretion, it controls the spatial organization of exocytosis.\",\n      \"method\": \"Live-cell imaging of GFP-Rab6; siRNA knockdown of Rab6 and kinesin-1; co-localization of vesicles with ELKS-positive cortical sites; secretion assays\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live imaging plus RNAi with functional readouts, interaction with ELKS validated, multiple orthogonal methods\",\n      \"pmids\": [\"17681140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"R6IP1 (Rab6-interacting protein 1) links Rab6 and Rab11 function: R6IP1 binds both Rab6 (targeting it to Golgi) and Rab11A (GTP-bound). Overexpression of R6IP1 promotes Rab11A-Rab6 interaction (FRET/FLIM) and causes pericentriolar accumulation of Rab11-positive recycling endosomes. R6IP1 function is also required during metaphase and cytokinesis.\",\n      \"method\": \"Yeast two-hybrid; co-immunoprecipitation; FRET/FLIM live-cell imaging; siRNA depletion; immunofluorescence; cell cycle analysis\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple interaction methods including quantitative FRET/FLIM, plus RNAi functional studies; multiple orthogonal methods\",\n      \"pmids\": [\"17725553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Rab6 depletion suppresses Golgi ribbon fragmentation/dispersal induced by ZW10/RINT-1 or COG complex inactivation (epistatic relationship). Dominant-negative Rab6 and C-terminal Bicaudal-D fragment (which interferes with dynactin/dynein) both suppress ZW10-knockdown-induced Golgi disruption. Rab6 therefore acts upstream in two separate retrograde tether-dependent Golgi trafficking pathways (ZW10/RINT-1 and COG).\",\n      \"method\": \"siRNA epistasis experiments; dominant-negative Rab6 expression; dominant-negative Bicaudal-D fragment; immunofluorescence; multiple Rab depletion combinations\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic genetic epistasis with multiple orthogonal perturbations, clear pathway placement\",\n      \"pmids\": [\"17699596\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"TMF/ARA160 is functionally involved in two Rab6-dependent retrograde pathways: retrograde transport of Shiga toxin from endosomes to TGN, and retention of specific Golgi enzymes (GalNAc-T2 but not GalT) at the Golgi. TMF localizes to cisternal tips/budding structures at the Golgi as shown by immunoelectron microscopy.\",\n      \"method\": \"siRNA knockdown of TMF and Rab6; Shiga toxin transport assay; immunofluorescence; immunoelectron microscopy; chimeric protein domain swap experiments\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — siRNA knockdown of both proteins with multiple functional readouts, ultrastructural localization by EM, domain swap experiments\",\n      \"pmids\": [\"17698061\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"SCYL1BP1 (GORAB) localizes to the Golgi apparatus and interacts with Rab6, functioning as a golgin. Loss-of-function mutations in SCYL1BP1 cause gerodermia osteodysplastica, associating Rab6-dependent secretory pathway defects with age-related connective tissue changes.\",\n      \"method\": \"Identification of disease-causing mutations; subcellular localization studies; interaction assays between GORAB and Rab6\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — disease-associated loss-of-function mutations, localization confirmed, Rab6 interaction demonstrated, single study\",\n      \"pmids\": [\"18997784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"DYNLRB1 (dynein light chain) specifically interacts with all three Rab6 isoforms and co-localizes at the Golgi. DYNLRB1 shows preferred association with GTP-bound Rab6A but GDP-bound Rab6A' and Rab6B, representing the first direct interaction identified between Rab6 and the dynein complex.\",\n      \"method\": \"Yeast two-hybrid; co-immunoprecipitation; pulldown with GTP/GDP-loaded Rab6 isoforms; immunofluorescence co-localization\",\n      \"journal\": \"Cell motility and the cytoskeleton\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two-hybrid confirmed by co-IP and pulldown with nucleotide-state specificity, single lab\",\n      \"pmids\": [\"18044744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Three Rab6a effectors (PIST, BicaudalD2, p150(Glued)) bind activated Rab6a through >15-kDa coiled-coil domains with Kd values in the high-nanomolar to low-micromolar range. BicaudalD2 and p150 binding moderately inhibits intrinsic Rab6a GTPase activity; PIST binding does not. Effectors bind in an apparent single-step reaction with relatively rapid on- and off-rates.\",\n      \"method\": \"In vitro biophysical binding assays (SPR, fluorescence); identification of minimal binding domains; GTPase activity assays with bound effectors\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — quantitative in vitro biophysical analysis with multiple effectors, kinetic and equilibrium constants determined, GTPase modulation measured\",\n      \"pmids\": [\"19019823\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of Rab6a(GTP) in complex with a 378-residue fragment of Rab6IP1 (containing RUN and PLAT domains) solved at 3.2 Å. The first and last alpha-helices of the RUN domain mediate binding to switch I, switch II, and the interswitch region of Rab6. Comparison with Rab6-GCC185 complex reveals conformational flexibility in the conserved hydrophobic triad of Rab6 that enables recognition of compositionally distinct effectors.\",\n      \"method\": \"X-ray crystallography; structure determination at 3.2 Å resolution; structural comparison with Rab6-GCC185 complex\",\n      \"journal\": \"Structure (London, England : 1993)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure determination with functional domain mapping; structural basis for Rab6 effector promiscuity revealed\",\n      \"pmids\": [\"19141279\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"BICDR-1 (Bicaudal-D-related protein 1) is a Rab6 effector that interacts with kinesin Kif1C and the dynein/dynactin complex, and accumulates Rab6 secretory vesicles in the pericentrosomal region of young neurons, restricting anterograde secretory transport and inhibiting neuritogenesis. BICDR-1 expression declines during development, permitting later anterograde transport required for neurite outgrowth.\",\n      \"method\": \"Co-immunoprecipitation; live-cell imaging; siRNA knockdown; zebrafish morpholino neural development assay; vesicle motility measurements\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple interaction assays, live imaging, in vivo zebrafish validation, multiple orthogonal methods\",\n      \"pmids\": [\"20360680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Rab33B and Rab6 act sequentially in an intra-Golgi retrograde trafficking Rab cascade: Rab6 acts downstream of Rab33B (overexpression of GTP-Rab33B induces dissociation of Rab6 from Golgi membranes). Efficient GTP-Rab6-induced relocation of Golgi enzymes to the ER is Rab33B-dependent, but not vice versa.\",\n      \"method\": \"siRNA epistasis experiments; overexpression of GTP-restricted Rab mutants; immunofluorescence; Golgi morphology analysis; Shiga toxin transport assay\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — systematic epistasis with multiple Rab perturbations establishing pathway order, multiple transport readouts\",\n      \"pmids\": [\"20163571\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Rab8A associates with exocytotic vesicles in a Rab6-dependent manner. Rab8A is required for docking and fusion (but not budding or motility) of exocytotic carriers. MICAL3 links Rab8A and ELKS at the cell cortex; MICAL3 monooxygenase activity is required for vesicle-docking complex remodeling and fusion. Rab6 and Rab8 thus cooperate sequentially in constitutive exocytosis.\",\n      \"method\": \"Live-cell imaging; siRNA knockdown of Rab6 and Rab8; co-immunoprecipitation; MICAL3 catalytic mutant expression; vesicle docking/fusion quantification\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple interaction assays, live imaging of vesicle behavior, mutagenesis of MICAL3 catalytic domain, multiple orthogonal methods\",\n      \"pmids\": [\"21596566\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The Ric1-Rgp1 complex is the guanine nucleotide exchange factor (GEF) for Rab6A in human cells. Both Ric1 and Rgp1 are required to catalyze nucleotide exchange on Rab6A and preferentially bind its GDP-bound form. Loss of Ric1 or Rgp1 destabilizes Rab6 and blocks retrograde transport of mannose-6-phosphate receptors to the Golgi. Rab33B-GTP binds the C-terminus of Ric1, establishing a Rab33B→Ric1/Rgp1→Rab6A cascade.\",\n      \"method\": \"In vitro nucleotide exchange assay with recombinant proteins; co-immunoprecipitation; siRNA knockdown; retrograde transport assay for mannose-6-phosphate receptors; domain-binding studies\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro GEF activity demonstrated with recombinant proteins, functional validation by RNAi, Rab cascade established\",\n      \"pmids\": [\"23091056\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Rab6 depletion causes accumulation of trans-Golgi clathrin-coated and COPI-coated vesicles and an increase of >50% in Golgi cisternae number. Rab6 is essential for trafficking of these two morphological classes of coated vesicles at the trans-Golgi.\",\n      \"method\": \"siRNA knockdown of Rab6; electron microscopy and electron tomography; quantitative morphometric analysis\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — unbiased high-resolution electron tomography with quantitative analysis in Rab6-depleted cells\",\n      \"pmids\": [\"22335553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Rab6A/A' are required for post-Golgi trafficking of TNF from TGN-derived tubular carriers to the cell surface in LPS-activated macrophages. Rab6 localizes to p230-positive TGN tubular carriers, and its depletion reduces carrier egress and partially reduces p230 membrane association. Both Rab6 isoforms are needed for macrophage Golgi organization and efficient post-Golgi TNF transport.\",\n      \"method\": \"siRNA and shRNA depletion; dominant-negative mutants; live-cell imaging of Rab6-GFP on TGN tubular carriers; secretion assays; electron microscopy\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple depletion approaches, live imaging, EM, secretion assays; multiple orthogonal methods\",\n      \"pmids\": [\"23437303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"COH1 (VPS13B) Golgi localization depends on RAB6: RAB6A/A' knockdown prevents COH1 localization to the Golgi, constitutively inactive RAB6_T27N increases solubilization of COH1 from membranes, and constitutively active RAB6_Q72L preferentially co-immunoprecipitates with COH1. COH1 depletion in primary neurons impairs neurite outgrowth.\",\n      \"method\": \"siRNA knockdown; co-immunoprecipitation with RAB6 mutants; lipid membrane fractionation; neurite outgrowth assay in primary neurons\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple Rab6 mutant approaches plus co-IP, neuronal functional readout, multiple orthogonal methods\",\n      \"pmids\": [\"25492866\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"KIF1C transports Rab6A vesicles and influences Golgi organization by binding Rab6A directly at both its motor domain and C-terminus. Rab6A binding to the KIF1C motor domain inhibits microtubule interaction in vitro and in cells. KIF1C depletion slows protein delivery to the cell surface, impairs vesicle motility, and causes Golgi fragmentation. KIF1C can protect Golgi from fragmentation independently of motor function when both Rab6A-binding sites are intact.\",\n      \"method\": \"In vitro microtubule interaction assay; pulldown; co-immunoprecipitation; siRNA knockdown; live-cell imaging; cargo delivery assay\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of motor-domain inhibition by Rab6A binding, combined with cell-based functional studies and mechanistic mutagenesis\",\n      \"pmids\": [\"25821985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"BICD2 stabilizes GTP-bound Rab6A on Golgi membranes: BICD2 knockdown reduces active Rab6A levels at the Golgi, and overexpression of C-terminal BICD2 decreases GFP-Rab6A exchange rate at Golgi (by FRAP). Rab6A and BICD2 jointly mediate COPI-independent Golgi-to-ER retrograde transport (Golgi tubule fusion with ER in BFA-treated cells).\",\n      \"method\": \"Golgi-targeting reconstitution in permeabilized cells; immunofluorescence; FRAP; siRNA knockdown; BFA-induced Golgi-to-ER transport assay\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reconstitution assay, FRAP, multiple functional transport assays; multiple orthogonal methods in one study\",\n      \"pmids\": [\"25962623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"GORAB missense mutations (p.Ala220Pro and p.Ser175Phe) in the IGRAB domain disrupt RAB6 binding and Golgi targeting of GORAB. ARF5 (GTP-bound) also binds the same IGRAB domain, and the p.Ala220Pro mutation abrogates both RAB6 and ARF5 binding while p.Ser175Phe selectively impairs ARF5 binding.\",\n      \"method\": \"Yeast two-hybrid screening; immunofluorescence; Brefeldin A treatment; mutagenesis; protein interaction assays\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus functional localization with mutagenesis, single lab\",\n      \"pmids\": [\"26000619\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"RAB6A knockout mouse embryonic fibroblasts (MEFs) show altered Golgi morphology, decreased Golgi-associated levels of Rab6 effectors (Bicaudal-D and myosin II), delayed VSV-G secretion, and protection against ricin toxicity. RAB6A homozygous null mice die at early embryonic development, establishing RAB6A as an essential gene.\",\n      \"method\": \"Conditional RAB6A knockout using Cre-loxP/tamoxifen system; Western blot; immunofluorescence; secretion assays; ricin toxicity assays\",\n      \"journal\": \"Biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with multiple phenotypic readouts, in vivo lethality established, multiple assays\",\n      \"pmids\": [\"26304202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In melanocytes, the RAB6/ELKS-dependent secretory pathway directly transports and docks Golgi-derived carriers (carrying MART-1 and TYRP2/DCT) to melanosomes, controlling melanosome formation, maturation, and pigment synthesis. RAB6 KO mice display pigmentation defects.\",\n      \"method\": \"Live-cell imaging; siRNA knockdown; RAB6 KO mouse model; cargo tracking; melanosome maturation assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live imaging plus in vivo mouse KO plus cargo tracking, multiple orthogonal methods\",\n      \"pmids\": [\"28607494\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Rab6-dependent retrograde transport of LAT (linker for activation of T cells) through the Golgi-TGN is required for its polarized delivery to the immune synapse and for TCR-mediated T lymphocyte activation. This retrograde traffic also depends on Syntaxin-16. Rab6 KO CD4+ T lymphocytes show impaired TCR stimulation in vivo.\",\n      \"method\": \"siRNA knockdown of Rab6 and Syntaxin-16 in human cells; Rab6 KO mouse CD4+ T cells; LAT trafficking assays; immune synapse formation assays; TCR stimulation assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent perturbation approaches (siRNA and KO mouse), in vitro and in vivo validation, functional signaling readout\",\n      \"pmids\": [\"29440364\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"RAB6 and microtubules restrict protein secretion to focal-adhesion-juxtaposed hotspots at the cell surface. Most post-Golgi carriers are RAB6-positive regardless of cargo, and RAB6 inactivation leads to broad reduction of protein secretion.\",\n      \"method\": \"Synchronized secretion assay (RUSH system); live-cell imaging; siRNA/dominant-negative Rab6 inactivation; colocalization with focal adhesion markers\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — synchronized secretion assay with live imaging, dominant-negative plus siRNA, multiple cargos tested\",\n      \"pmids\": [\"31142554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Rab6 negatively regulates cell migration by interacting with Cdc42 and Trio (a GEF for Cdc42), thereby suppressing Cdc42 activity. Loss of Rab6 promotes actin protrusion formation and upregulates Cdc42 activity while downregulating myosin II phosphorylation.\",\n      \"method\": \"Rab6 KO/knockdown; Cdc42 GTPase activity assay; co-immunoprecipitation of Rab6 with Cdc42 and Trio; actin protrusion quantification; cell migration assays in vitro and in vivo\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus GTPase assay plus functional KO phenotype, single lab, multiple methods\",\n      \"pmids\": [\"30830239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ELKS1 captures Rab6-positive Golgi-derived vesicular cargo at presynaptic nerve terminals via Golgin-like mechanisms. Knockout and rescue experiments establish that ELKS1 captures Rab6 cargo; the capturing mechanism can be transferred to mitochondria by mistargeting ELKS1 or Rab6.\",\n      \"method\": \"ELKS1 and Rab6 knockout and rescue experiments; live-cell imaging; mitochondria mistargeting experiments; presynaptic vesicle assays in neurons\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout plus rescue plus domain transfer experiment, multiple orthogonal approaches establishing mechanism\",\n      \"pmids\": [\"32521280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Newly synthesized TrkB receptors traffic through the secretory pathway in Rab6-positive carriers and are directly delivered into the axon. The combined activity of kinesin-1 and kinesin-3 drives formation and anterograde transport of these TrkB/Rab6-positive secretory carriers beyond the proximal axon.\",\n      \"method\": \"Microfluidic compartmental devices; inducible secretion assay; live-cell imaging; siRNA/knockout of kinesin-1 and kinesin-3; Rab6 co-localization assays\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — inducible secretion assay plus live imaging plus kinesin knockouts, multiple orthogonal approaches\",\n      \"pmids\": [\"33571451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Post-Golgi transport of RAB6+ vesicles in apical radial glia (aRG) cells occurs toward microtubule minus ends and depends on dynein and LIS1 (dynein activator). Double knockout of RAB6A/A' and RAB6B impairs apical localization of the apical determinant Crumbs3 (CRB3) and induces retraction of the apical process, leading to aRG delamination and ectopic division. These defects are phenocopied by LIS1 knockout.\",\n      \"method\": \"In situ subcellular live imaging; conditional RAB6 double knockout; LIS1 knockout; CRB3 localization assays; neuroepithelial integrity analysis\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic double knockout plus live imaging, epistatic validation with LIS1, in vivo relevance established\",\n      \"pmids\": [\"35979738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"A cytosolic complex of p62 and Rab6 associates with TGN38/41 and is required for budding of exocytic vesicles from the TGN. Immunodepletion or competing peptides targeting p62, Rab6, or TGN38/41 cytoplasmic domains completely inhibit vesicle budding in a cell-free system.\",\n      \"method\": \"Co-immunoprecipitation from cell extracts; cell-free vesicle budding assay; immunodepletion; competing peptide inhibition; sizing column and velocity sedimentation\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cell-free reconstitution of vesicle budding with multiple inhibitory approaches (immunodepletion and competing peptides)\",\n      \"pmids\": [\"8349729\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Rab6 in Drosophila photoreceptors controls rhodopsin anterograde transport through the Golgi; GTPase-defective Rab6(Q71L) prevents maturation of rhodopsin beyond an immature 40-kDa form, depletes Rh1 and Rh3 levels, and causes retinal degeneration.\",\n      \"method\": \"Transgenic overexpression in Drosophila photoreceptors; Western blot analysis of rhodopsin forms; histological analysis; heat-shock rhodopsin pulse-chase\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo transgenic Drosophila model with multiple Rab6 mutants, rhodopsin maturation assay, histological validation\",\n      \"pmids\": [\"9685396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"In platelets, Rab6 is phosphorylated by protein kinase C (PKC) in a thrombin-stimulated manner. PKC phosphorylation of Rab6 increases GTP affinity ~3-fold, does not alter GTPase activity, and causes translocation of Rab6 from platelet particulate fractions to the cytosol.\",\n      \"method\": \"Metabolic [32P] labeling; PKC inhibitor (Ro-31-8220); cell fractionation; in vitro PKC phosphorylation of recombinant Rab6C; nucleotide binding affinity measurements\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro phosphorylation with recombinant protein plus in vivo labeling, quantitative binding measurements, specific inhibitor control\",\n      \"pmids\": [\"10455022\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RAB6A is a Golgi-localized small GTPase (active GTP-bound form on Golgi and transport intermediates) that regulates multiple trafficking steps: (1) intra-Golgi retrograde transport involving coated vesicle trafficking at the trans-Golgi; (2) a COPI-independent, microtubule- and dynein/dynactin-dependent retrograde Golgi-to-ER pathway (primarily via Rab6A isoform); (3) retrograde endosome-to-TGN transport (primarily via Rab6A' isoform); (4) post-Golgi anterograde secretory vesicle transport to focal-adhesion hotspots at the plasma membrane, where it recruits kinesin-1 for processive microtubule-based movement and directs vesicle targeting via the cortical tether ELKS; (5) coordination of exocytic vesicle docking/fusion through sequential handoff to Rab8 via MICAL3; and (6) mitotic progression via regulation of dynein/dynactin dynamics at kinetochores. These activities are mediated by a diverse array of effectors recruited to GTP-Rab6, including Rabkinesin-6/KIF20A, KIF1C, dynactin (p150^Glued), DYNLRB1, BicaudalD/BICD2, BICDR-1, ELKS, TMF, Rab6IP1/2, GAPCenA (its cognate GAP), and Ric1-Rgp1 (its cognate GEF), with the Rab6A vs. Rab6A' isoforms (differing by only 3 amino acids from alternative splicing) performing non-overlapping functions due to differential effector binding.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RAB6A is a Golgi-localized small GTPase that serves as a master organizer of multiple membrane trafficking steps, switching between GDP- and GTP-bound states to recruit a diverse array of effectors to the Golgi and to transport carriers [#0, #16]. Its Golgi targeting requires geranylgeranylation and N-terminal sequences, with the nucleotide state governing both its prenylation and its membrane cycle through RabGDI extraction [#1, #2, #3]; the Ric1-Rgp1 complex acts as its GEF and GAPCenA as its GAP, the latter being shared with the kinetochore-associated functions of the protein [#32, #9]. In its GTP-bound form RAB6 controls intra-Golgi retrograde transport and trafficking of trans-Golgi coated vesicles, and drives a COPI-independent, microtubule- and dynactin/dynein-dependent Golgi-to-ER retrograde pathway that recycles Golgi glycosylation enzymes [#0, #33, #6, #17]. RAB6 achieves these movements by recruiting cytoskeletal effectors—dynactin (p150Glued), the dynein light chain DYNLRB1, BICD2/BICDR-1, and the kinesins Rabkinesin-6/KIF20A and KIF1C—coupling carriers to bidirectional microtubule-based transport [#14, #26, #27, #29, #36, #7]. At the cell periphery RAB6 marks the majority of post-Golgi secretory carriers and, with kinesin-1, targets them to focal-adhesion-juxtaposed plasma-membrane hotspots defined by the cortical tether ELKS, where a sequential handoff to Rab8 via MICAL3 controls vesicle docking and fusion [#21, #42, #31, #44]. The gene encodes two splice isoforms, Rab6A and Rab6A', differing by three amino acids, that perform non-overlapping functions: Rab6A predominates in Golgi-to-ER recycling while Rab6A' governs endosome-to-TGN retrograde transport and mitotic progression by regulating dynein/dynactin and the Mad2 spindle checkpoint at kinetochores [#11, #13, #19, #20]. RAB6A is an essential gene whose loss is embryonic lethal in mice and whose secretory functions support pigmentation, T-cell receptor signaling, and neuronal development [#39, #40, #41, #46]. Loss-of-function mutations in the RAB6 effector GORAB cause gerodermia osteodysplastica, linking RAB6-dependent secretory trafficking to connective-tissue homeostasis [#25].\",\n  \"teleology\": [\n    {\n      \"year\": 1993,\n      \"claim\": \"Established RAB6 as a component of the secretory machinery by showing a cytosolic p62-Rab6 complex required for budding of exocytic vesicles from the TGN.\",\n      \"evidence\": \"Cell-free vesicle budding assay with immunodepletion and competing peptides\",\n      \"pmids\": [\"8349729\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the GTPase cycle or effector logic\", \"p62 identity and direct biochemical contacts not resolved\"]\n    },\n    {\n      \"year\": 1994,\n      \"claim\": \"Placed RAB6 functionally at the intra-Golgi transport step and defined the membrane-targeting determinants and GDI-dependent membrane cycle, answering where and how the GTPase acts.\",\n      \"evidence\": \"Overexpression of GTP/GDP mutants with transport assays; chimeric prenylation mutants; yeast complementation; in vitro membrane extraction with RabGDI\",\n      \"pmids\": [\"7798313\", \"8264642\", \"8175798\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Effectors mediating transport not yet identified\", \"Distinction between intra-Golgi and retrograde-to-ER roles not resolved\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Showed that the nucleotide-bound conformation controls RAB6 prenylation and GDI-dependent extraction, linking the GTPase switch to the membrane attachment cycle.\",\n      \"evidence\": \"Conformational mutants in insect cells with Triton X-114 partitioning; two-hybrid plus membrane extraction with GDI beta\",\n      \"pmids\": [\"8521955\", \"7782346\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab/single-study for prenylation-conformation coupling\", \"Novel two-hybrid interactor left unidentified\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Revealed a microtubule-dependent Golgi-to-ER retrograde route by showing GTP-RAB6 redistributes Golgi enzymes to the ER, separating retrograde recycling from forward secretion.\",\n      \"evidence\": \"Rab6 mutant overexpression in HeLa with glycosylation/fractionation readouts and nocodazole microtubule disruption\",\n      \"pmids\": [\"9050864\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Motor/tether machinery driving the route not yet defined\", \"Relationship to COPI not yet established\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Identified the first RAB6 motor effector, demonstrating that the GTPase couples membranes to microtubule motors via Rabkinesin-6.\",\n      \"evidence\": \"Two-hybrid, co-IP, GST pulldown, and dominant-negative effector-domain overexpression\",\n      \"pmids\": [\"9438855\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Directionality of motor transport not resolved\", \"Did not address dynein-based retrograde movement\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Defined the COPI-independent nature of RAB6 retrograde transport and identified its cognate GAP, while linking RAB6 effectors to membrane tethering golgins.\",\n      \"evidence\": \"Live imaging of FP-Rab6 carriers and Shiga toxin transport; COPI-antibody microinjection; in vitro GAP assay for GAPCenA; golgin protein-blot binding\",\n      \"pmids\": [\"10562278\", \"10202141\", \"10209123\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"GEF still unknown at this stage\", \"Golgin binding lacked reciprocal in-solution validation (idx 10)\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Resolved that two splice isoforms differing by three amino acids carry distinct functions, and uncovered a mitotic role through the Rab6-binding kinesin in cytokinesis.\",\n      \"evidence\": \"Gene structure analysis, isoform overexpression with two-hybrid effector binding; Rab6-KIFL localization and inhibitory-antibody microinjection with time-lapse\",\n      \"pmids\": [\"11071909\", \"11060022\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism coupling RAB6 to the cytokinetic apparatus incomplete\", \"Single-residue determinant of isoform divergence functionally probed but structural basis unknown\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Assigned endosome-to-TGN retrograde transport specifically to the Rab6A' isoform with defined SNARE partners, separating isoform functions in distinct trafficking routes.\",\n      \"evidence\": \"Permeabilized-cell transport assay with isoform-specific and SNARE inhibition\",\n      \"pmids\": [\"11839770\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Effectors specific to the Rab6A' endosome route not fully enumerated\", \"Coordination with Golgi-to-ER route unresolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Established RAB6 as the specificity factor recruiting dynactin to Golgi membranes and added new Golgi-recruited effectors, building the dynein/dynactin-based retrograde transport model.\",\n      \"evidence\": \"Pulldown/co-IP with recombinant Rabs and Golgi recruitment assays; two-hybrid plus recruitment for Rab6IP2A/B with Shiga toxin readout\",\n      \"pmids\": [\"12401177\", \"11929610\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs. adaptor-mediated dynactin contact not fully resolved\", \"Rab6IP2 confirmed by single lab only\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Provided direct evidence that active GTP-RAB6 resides on the Golgi and transport intermediates and shapes carrier geometry, validating the GTPase as conformationally active in situ.\",\n      \"evidence\": \"Conformation-specific intrabodies (GFP-tagged) for live and fixed imaging\",\n      \"pmids\": [\"12738866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spatial regulation of GTP/GDP cycling on carriers not mapped\", \"GEF/GAP localization relative to active pool not defined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Confirmed both isoforms drive dynactin-dependent Golgi-to-ER recycling and demonstrated by RNAi that RAB6 organizes the Golgi, integrating loss-of-function with overexpression evidence.\",\n      \"evidence\": \"Isoform-specific siRNA, GTP-mutant overexpression, dynamitin/Bicaudal-D dominant-negatives, immunofluorescence\",\n      \"pmids\": [\"15483056\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative isoform contribution to recycling not separated here\", \"Did not address mitotic functions\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Dissected Rab6A' as the dominant retrograde isoform and uncovered a kinetochore function in inactivating the Mad2 checkpoint via dynein/dynactin dynamics, uncoupling trafficking and mitotic roles.\",\n      \"evidence\": \"Isoform-specific siRNA with Shiga toxin and cell-cycle readouts; dominant-negative and GAPCenA depletion with Mad2/p150Glued kinetochore staining; Ile62 mutagenesis\",\n      \"pmids\": [\"16536738\", \"16395330\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How a Golgi GTPase localizes activity to kinetochores not mechanistically resolved\", \"GEF for the kinetochore pool unidentified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined RAB6's exocytic targeting role, its epistatic position upstream of retrograde tether complexes, and effector links bridging RAB6 to Rab11 and golgin TMF.\",\n      \"evidence\": \"Live imaging and siRNA for Rab6/kinesin-1 with ELKS colocalization; siRNA epistasis with ZW10/RINT-1 and COG; two-hybrid/FRET-FLIM for R6IP1; TMF binding and RNAi with immuno-EM\",\n      \"pmids\": [\"17681140\", \"17699596\", \"17725553\", \"17698061\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which ELKS captures carriers not yet defined\", \"TMF and R6IP2 functional details confined to single labs\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Provided quantitative biophysical parameters for effector binding, identified a dynein light chain partner, and linked RAB6 effector GORAB to human disease.\",\n      \"evidence\": \"SPR/fluorescence binding kinetics and GTPase modulation for PIST/BICD2/p150; two-hybrid/co-IP/pulldown for DYNLRB1; GORAB disease-mutation and interaction studies\",\n      \"pmids\": [\"19019823\", \"18044744\", \"18997784\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"DYNLRB1 nucleotide-state preferences differ across isoforms without structural explanation\", \"GORAB mechanism in disease pathology not detailed (Medium)\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Provided the structural basis for RAB6 effector promiscuity by solving the Rab6a(GTP)-Rab6IP1 complex and revealing conformational flexibility in its hydrophobic triad.\",\n      \"evidence\": \"X-ray crystallography at 3.2 Å with comparison to Rab6-GCC185\",\n      \"pmids\": [\"19141279\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structures of motor- and tether-effector complexes not solved\", \"Isoform-specific structural differences not captured\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Embedded RAB6 in a Rab33B->Rab6 retrograde cascade and identified BICDR-1 as a developmentally regulated effector restraining anterograde secretory transport in neurons.\",\n      \"evidence\": \"siRNA epistasis with GTP-Rab33B; co-IP, live imaging, siRNA, and zebrafish morpholino for BICDR-1/Kif1C\",\n      \"pmids\": [\"20163571\", \"20360680\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"GEF connecting Rab33B to Rab6 not yet identified at this stage\", \"Developmental switch controlling BICDR-1 levels not mechanistically defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined a sequential RAB6-to-Rab8 handoff for exocytosis, showing RAB6 recruits Rab8 to carriers and MICAL3 monooxygenase activity remodels docking complexes for fusion.\",\n      \"evidence\": \"Live imaging, siRNA of Rab6/Rab8, co-IP, and MICAL3 catalytic-mutant expression with docking/fusion quantification\",\n      \"pmids\": [\"21596566\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular trigger for the Rab6-to-Rab8 conversion not defined\", \"MICAL3 substrate during remodeling not identified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified the Ric1-Rgp1 GEF completing the RAB6 regulatory cycle and closing the Rab33B->Ric1/Rgp1->Rab6 cascade, and resolved the coated-vesicle defects of RAB6 loss ultrastructurally.\",\n      \"evidence\": \"In vitro nucleotide exchange with recombinant proteins, co-IP, siRNA with M6PR transport assay; electron tomography of Rab6-depleted Golgi\",\n      \"pmids\": [\"23091056\", \"22335553\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spatial regulation of GEF activation on Golgi not mapped\", \"Whether the cascade applies to all RAB6 routes unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Extended RAB6's post-Golgi secretory role to immune effector output by showing both isoforms are needed for TGN-to-surface TNF carrier egress in activated macrophages.\",\n      \"evidence\": \"siRNA/shRNA depletion, dominant-negative mutants, live imaging of TGN carriers, secretion assays, EM\",\n      \"pmids\": [\"23437303\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cargo-selectivity of RAB6 carriers not addressed\", \"Link to inflammatory signaling pathways not explored\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified VPS13B/COH1 as a RAB6-dependent Golgi-recruited factor required for neurite outgrowth, broadening RAB6's role in neuronal membrane organization.\",\n      \"evidence\": \"siRNA, co-IP with Rab6 mutants, membrane fractionation, neurite outgrowth in primary neurons\",\n      \"pmids\": [\"25492866\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trafficking step served by COH1 not precisely defined\", \"Direct vs. indirect RAB6-COH1 contact not fully resolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined motor- and adaptor-level mechanisms—KIF1C autoinhibition by RAB6A binding and BICD2 stabilization of active RAB6—and refined GORAB disease mechanism, sharpening the transport machinery model.\",\n      \"evidence\": \"In vitro microtubule assays and cell studies for KIF1C; FRAP/reconstitution for BICD2; two-hybrid/mutagenesis for GORAB-RAB6/ARF5; RAB6A knockout MEFs with secretion and ricin assays plus embryonic lethality\",\n      \"pmids\": [\"25821985\", \"25962623\", \"26000619\", \"26304202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How motor autoinhibition is relieved on carriers not resolved\", \"GORAB-ARF5 binding interface in disease confirmed in single lab (Medium)\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated a physiological RAB6/ELKS secretory pathway delivering melanogenic cargo to melanosomes, with pigmentation defects in RAB6 KO mice establishing in vivo relevance.\",\n      \"evidence\": \"Live imaging, siRNA, RAB6 KO mouse, cargo tracking, melanosome maturation assays\",\n      \"pmids\": [\"28607494\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Selectivity of RAB6 carriers for melanosomal cargo not mechanistically defined\", \"Role of isoforms in melanocytes not separated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected RAB6 retrograde trafficking to adaptive immunity by showing RAB6/Syntaxin-16-dependent LAT recycling is required for immune synapse delivery and TCR signaling.\",\n      \"evidence\": \"siRNA in human cells, RAB6 KO mouse CD4+ T cells, LAT trafficking and TCR stimulation assays\",\n      \"pmids\": [\"29440364\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How retrograde LAT routing achieves polarized synapse delivery not fully resolved\", \"Effector mediating LAT capture not identified\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed RAB6 spatially confines secretion to focal-adhesion-juxtaposed hotspots and uncovered an additional role in suppressing Cdc42 to restrain cell migration, broadening RAB6 beyond canonical secretion.\",\n      \"evidence\": \"RUSH synchronized secretion with live imaging and Rab6 inactivation; Cdc42 GTPase assay, co-IP with Cdc42/Trio, migration assays\",\n      \"pmids\": [\"31142554\", \"30830239\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanistic coupling of secretion hotspots to focal adhesions not defined\", \"Rab6-Cdc42/Trio interaction confirmed in single lab (Medium)\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established the molecular logic of carrier capture by showing ELKS1 tethers RAB6 cargo at presynaptic terminals through golgin-like mechanisms transferable to ectopic organelles.\",\n      \"evidence\": \"ELKS1 and Rab6 knockout/rescue, live imaging, mitochondria mistargeting experiments in neurons\",\n      \"pmids\": [\"32521280\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the direct ELKS1-RAB6 tethering contact not defined\", \"Generality across cell types beyond neurons not established\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed RAB6-positive carriers deliver newly synthesized TrkB receptors into axons via combined kinesin-1/kinesin-3 activity, defining a directional anterograde transport mechanism in neurons.\",\n      \"evidence\": \"Microfluidic compartmental secretion assay, live imaging, kinesin-1/kinesin-3 knockdown/knockout, Rab6 colocalization\",\n      \"pmids\": [\"33571451\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How motor handoff is regulated along the axon not resolved\", \"Cargo-specificity of RAB6 axonal carriers not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated RAB6 carriers move toward microtubule minus ends via dynein/LIS1 in apical radial glia to deliver apical determinants, linking RAB6 trafficking to neuroepithelial integrity in vivo.\",\n      \"evidence\": \"In situ live imaging, conditional RAB6 double knockout, LIS1 knockout, CRB3 localization, neuroepithelial integrity analysis\",\n      \"pmids\": [\"35979738\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Switch between minus-end (dynein) and plus-end (kinesin) carrier transport not mechanistically resolved\", \"Direct vs. effector-mediated dynein/LIS1 coupling not defined here\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RAB6 selects among its many competing effectors and trafficking routes in space and time, and what governs the directional switch between dynein-driven retrograde and kinesin-driven anterograde transport on individual carriers, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No model integrates effector competition with carrier-specific motor selection\", \"Spatial control of GEF/GAP activation on distinct membrane domains not mapped\", \"Isoform-specific effector code not fully enumerated structurally\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [9, 27, 32, 16]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [14, 21, 31, 37]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 1, 16, 33]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [8, 16, 21, 42]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4, 47, 49]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [6, 14, 36, 46]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 8, 13, 42]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [21, 31, 33, 47]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [12, 19, 20]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [29, 45, 46, 40]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"KIF20A\", \"KIF1C\", \"BICD2\", \"DCTN1\", \"DYNLRB1\", \"ELKS\", \"TMF\", \"GORAB\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":8,"faith_pct":87.5}}