{"gene":"DDX19B","run_date":"2026-04-28T17:46:02","timeline":{"discoveries":[{"year":1999,"finding":"Human DBP5 (hDbp5/DDX19B) localizes to the cytoplasmic fibrils of the nuclear pore complex (NPC) via a direct interaction with the nucleoporin CAN/NUP214 (N-terminal region); a DEAD-box mutation (Glu→Gln) acts as a dominant-negative inhibitor of mRNA export in Xenopus oocytes, establishing that RNA-dependent ATPase activity is required for mRNA export.","method":"Co-immunoprecipitation, immunoelectron microscopy, direct binding assays, dominant-negative microinjection in Xenopus oocytes","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — reciprocal binding assays, in vivo localization, functional microinjection; independently replicated across yeast and human systems","pmids":["10428971"],"is_preprint":false},{"year":2004,"finding":"The N-terminal beta-propeller domain of yeast Nup159 (human NUP214 ortholog) directly binds Dbp5/DDX19; structure-based mutations in a conserved loop abolish Dbp5 binding in vitro, mislocalize Dbp5 from the NPC in vivo, and block mRNA export, demonstrating that NPC tethering of Dbp5 via Nup159 is essential for mRNA export.","method":"X-ray crystallography (2.5 Å), in vitro binding assays, structure-guided mutagenesis, in vivo mRNA export assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with mutagenesis and in vivo functional validation","pmids":["15574330"],"is_preprint":false},{"year":2006,"finding":"Inositol hexakisphosphate (InsP6) and the NPC-associated protein Gle1 together stimulate the RNA-dependent ATPase activity of Dbp5/DDX19B; InsP6 requires both Dbp5 and Gle1 for maximal binding and lowers the RNA concentration needed for half-maximal ATPase activity; overexpression of DBP5 suppresses mRNA export defects caused by InsP6/Gle1 loss.","method":"In vitro ATPase kinetic assays, genetic suppression, in vivo mRNA export assays","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with kinetic analysis, corroborated by independent parallel study (PMID:16783364)","pmids":["16783363"],"is_preprint":false},{"year":2006,"finding":"Gle1 is a direct cellular activator of Dbp5/DDX19B: Gle1 alone stimulates Dbp5 RNA binding and ATP hydrolysis, and InsP6 potentiates Gle1-mediated activation; a Gle1 point mutant deficient for Dbp5 stimulation in vitro shows mRNA export defects in vivo; dominant suppressor mutations in DBP5 and GLE1 mimic InsP6 effects in vitro.","method":"In vitro ATPase and RNA-binding assays, dominant suppressor mutagenesis, in vivo mRNA export assays","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with mutagenesis and in vivo correlation; simultaneous independent replication (PMID:16783363)","pmids":["16783364"],"is_preprint":false},{"year":2007,"finding":"Dbp5/DDX19B acts as an RNP remodeling protein at the NPC by displacing the RNA-binding protein Nab2 from mRNA; this remodeling requires the ADP-bound (not ATP-bound) form of Dbp5, indicating that ADP binding rather than ATP hydrolysis drives the conformational change for protein displacement.","method":"In vitro RNP remodeling assays, nucleotide-state-specific mutants, in vivo genetic analysis of nab2 and dbp5 mutants","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with nucleotide mutants plus in vivo genetic validation","pmids":["18082609"],"is_preprint":false},{"year":2007,"finding":"Dbp5/DDX19B functions in translation termination in S. cerevisiae: it physically interacts with release factor eRF1, genetically interacts with eRF1, eRF3, and Pab1, and its helicase activity is required for efficient stop-codon recognition and for recruitment of eRF3 into termination complexes.","method":"Co-immunoprecipitation, genetic interaction analysis, helicase-activity mutants, in vivo translation termination assays","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus genetic epistasis plus functional mutant analysis; highly cited foundational study","pmids":["17272721"],"is_preprint":false},{"year":2009,"finding":"Crystal structures of human DDX19B bound to RNA+AMPPNP and bound to NUP214 reveal that RNA binding and NUP214 binding to DDX19B are mutually exclusive; NUP214 decreases both RNA binding and ATPase activities of DDX19B; interactions are mediated by conserved residues.","method":"X-ray crystallography, in vitro ATPase and RNA-binding assays, mutagenesis","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 — crystal structures with biochemical validation and mutagenesis in human protein","pmids":["19219046"],"is_preprint":false},{"year":2009,"finding":"Crystal structures of human DDX19B in RNA-bound/prehydrolysis (closed cleft) and free/posthydrolysis (open cleft) states reveal an N-terminal alpha-helix that inserts between the two conserved RecA-like domains in the open conformation to negatively autoregulate ATPase activity; biochemical data confirm this N-terminal autoregulatory function.","method":"X-ray crystallography, biochemical ATPase assays, truncation analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structures in two functional states with biochemical validation","pmids":["19244245"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of the Nup214 N-terminal domain in complex with DDX19B (ADP-bound state) at 2.5 Å; the interaction surfaces show opposing surface potentials (helicase positive, Nup214 negative); binding interfaces are evolutionarily conserved, providing a structural basis for NPC docking of DDX19B.","method":"X-ray crystallography (2.5 Å), structural and biochemical analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — crystal structure of complex with functional interpretation","pmids":["19208808"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of the C-terminal domain of Dbp5/DDX19B (1.8 Å) reveals a RecA-like fold with a unique C-terminal alpha-helix and loop; structure-guided mutagenesis of conserved charged surface residues identifies the Gle1-binding interface; mutations that weaken Gle1 binding and ATPase stimulation in vitro are lethal in vivo.","method":"X-ray crystallography, structure-guided mutagenesis, in vitro ATPase assays, yeast viability assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus mutagenesis with in vitro and in vivo correlation","pmids":["19805289"],"is_preprint":false},{"year":2009,"finding":"RBM15 directly binds human DBP5 and facilitates DBP5's contact with mRNA in vivo; RBM15 co-localizes with DBP5 and NXF1 at the nuclear envelope; silencing RBM15 leads to cytoplasmic depletion and nuclear accumulation of mRNA, indicating RBM15 promotes recognition of NXF1-mRNP by DBP5 at the NPC.","method":"Co-immunoprecipitation, RNA immunoprecipitation, siRNA knockdown, fluorescence microscopy","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus in vivo functional knockdown; single lab study","pmids":["19786495"],"is_preprint":false},{"year":2011,"finding":"Nup159 functions as an ADP release factor for Dbp5/DDX19B: in vitro reconstitution assays show Nup159 is specifically required for ADP release from Dbp5, while Gle1-IP6 stimulates ATP binding to prime Dbp5 for RNA loading; a dbp5 mutant with reduced ADP binding bypasses the need for Nup159 interaction in vivo.","method":"In vitro nucleotide-binding and release assays, reconstitution, in vivo mutant analysis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with multiple biochemical assays plus in vivo rescue genetics","pmids":["21576266"],"is_preprint":false},{"year":2011,"finding":"ATP binding and hydrolysis are required for efficient Dbp5 association with NPCs; RNA-binding-deficient Dbp5 mutants are dominant-negative for mRNA export by competing with wild-type Dbp5 for Gle1 at NPCs; FRAP shows Dbp5 associates with NPCs very dynamically (~<1 sec); Dbp5-Gle1 interaction can be independent of Nup159.","method":"Mutant analysis, dominant-negative assays, FRAP (yeast and human cells), in vivo mRNA export assays","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (FRAP, genetic, functional) in two organisms","pmids":["21576265"],"is_preprint":false},{"year":2013,"finding":"DBP5/DDX19B contains a SLIP1-binding motif (SBM) and directly interacts with SLIP1 (a MIF4G-domain protein involved in translation initiation); crystal structure of SLIP1 bound to the DBP5 SBM was determined at 3.25 Å, identifying a physical link between the mRNA export factor and translational machinery.","method":"X-ray crystallography (3.25 Å), pull-down assays","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1 structure + Tier 3 pull-down; functional consequence not fully established","pmids":["23804756"],"is_preprint":false},{"year":2015,"finding":"Kinetic analysis of the Dbp5/DDX19B ATPase cycle shows that ATP binds weakly (KT ~4 mM) while ADP binds ~10-fold more tightly; RNA increases kcat and rate-limiting Pi release ~20-fold but Pi release remains rate-limiting even with RNA; identifying RNA binding and Pi release as critical biochemical transitions in the Dbp5 cycle.","method":"Stopped-flow kinetics, equilibrium binding assays, in vitro ATPase assays","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — detailed kinetic reconstitution with multiple methods","pmids":["26730886"],"is_preprint":false},{"year":2015,"finding":"Ddx19/Dbp5 is required for nuclear import of the transcriptional coactivator MKL1; this function is distinct from its mRNA export role; RNA-binding activity of Ddx19 (but not helicase or NPC-binding activities) is required; Ddx19 modulates the conformation of MKL1 to facilitate its interaction with Importin-β.","method":"siRNA knockdown, domain-mutant rescue assays, co-immunoprecipitation, nuclear import assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — clean KD with specific phenotype plus Co-IP and domain mapping; single lab","pmids":["25585691"],"is_preprint":false},{"year":2016,"finding":"Dbp5/DDX19B is required for nuclear export of both pre-ribosomal subunits in yeast; genetic and physical interactions occur with the ribosomal transport factor Nmd3; however, unlike mRNA export, ATPase-deficient dbp5 mutants and gle1 mutants do not block ribosomal export, indicating DDX19B supports ribosomal transport through NPC localization/capture rather than ATPase-dependent remodeling.","method":"Yeast temperature-sensitive mutants, co-immunoprecipitation, fluorescence microscopy, ATPase-deficient mutants","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with multiple mutant alleles plus Co-IP; single lab","pmids":["26872259"],"is_preprint":false},{"year":2017,"finding":"DDX19 (mammalian Dbp5 ortholog) participates in translation termination: it associates with translating ribosome fractions, interacts with pre-termination complexes in a nucleotide-dependent manner, increases termination complex formation and peptide release by eukaryotic release factors, and stabilizes ribosome complexes with elongation factors eEF1 and eEF2.","method":"Reconstituted mammalian in vitro translation system, sucrose gradient sedimentation, eRF1(AGQ) and non-hydrolysable GTP inhibitor assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro translation with multiple functional assays in human DDX19","pmids":["28180304"],"is_preprint":false},{"year":2017,"finding":"Ddx19 (human DDX19B ortholog) relocalizes from the nucleopore to the nucleus upon DNA damage or replication stress in an ATR/Chk1-dependent manner; nuclear Ddx19 resolves R-loops (DNA:RNA hybrids) via its helicase activity in vitro; mutation of a Chk1-phosphorylated residue disrupts Ddx19 interaction with Nup214 and allows nuclear relocalization; Ddx19 depletion causes R-loop accumulation, DNA damage, and replication fork progression defects.","method":"Live-cell imaging, R-loop immunofluorescence, in vitro helicase assay, ATR/Chk1 inhibitors, phosphorylation mutants, siRNA knockdown, DNA fiber assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods including in vitro helicase reconstitution, live imaging, and genetics; single lab but comprehensive","pmids":["28314779"],"is_preprint":false},{"year":2017,"finding":"Nup42 is required for efficient Dbp5/DDX19B activation: the Nup42 C-terminal domain binds Gle1/hGle1B at a site distinct from the Gle1-Dbp5 interface; a nup42-CTD/gle1-CTD/Dbp5 trimeric complex forms in the presence of IP6; deletion of NUP42 abrogates Gle1-Dbp5 interaction; Nup42 and IP6 stimulate Gle1/hGle1B activation of both yeast Dbp5 and human DDX19B in vitro in a non-additive manner.","method":"In vitro ATPase assays with recombinant proteins, co-immunoprecipitation, yeast and human cell mRNA export assays, structure-function mutagenesis","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro reconstitution with both yeast and human proteins plus in vivo functional correlation","pmids":["28869701"],"is_preprint":false},{"year":2018,"finding":"Nup159 does not accelerate ADP release from Dbp5/DDX19B; instead Gle1 slows ADP release; Mg2+ slows both ADP and ATP release and increases their affinities; Nup159 reduces Gle1-ADP-Dbp5 interaction ~18-fold, suggesting Nup159 aids Gle1 dissociation from ADP-bound Dbp5 rather than acting as a nucleotide exchange factor.","method":"Stopped-flow kinetics, fluorescence equilibrium binding assays, in vitro biochemical reconstitution","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — detailed kinetic analysis contradicting prior model, with multiple quantitative assays","pmids":["29782832"],"is_preprint":false},{"year":2019,"finding":"DDX19B is a negative regulator of type I interferon production: it inhibits TBK1- and IKKε-mediated phosphorylation of IRF3 by disrupting TBK1/IKKε-IRF3 interactions; DDX19B recruits Lamtor2 to form a TBK1-IKKε-Lamtor2-DDX19-IRF3 complex that promotes TBK1 and IKKε degradation; Ddx19 knockout mice show augmented type I IFN production.","method":"Ectopic overexpression, siRNA knockdown, co-immunoprecipitation, TALEN-generated knockout mice, virus infection assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, KO mouse, and functional assays; multiple orthogonal methods","pmids":["30699353"],"is_preprint":false},{"year":2019,"finding":"Dbp5/DDX19B contains an N-terminal Xpo1-dependent nuclear export signal; disruptions in Dbp5 nucleocytoplasmic transport result in tRNA export defects rather than mRNA export defects, indicating nuclear shuttling of Dbp5 is not essential for mRNP export but is specifically required for tRNA export.","method":"Alanine scanning mutagenesis (456 viable mutants), GFP reporter, genetic analysis, tRNA export assays in yeast","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 — systematic mutagenesis with separation-of-function alleles; single lab","pmids":["31453808"],"is_preprint":false},{"year":2020,"finding":"Dbp5 associates in close proximity with both Mex67 (mRNA export receptor) and Nab2 in a cellular complex; fusion of Dbp5 to Nup159 anchors it at the cytoplasmic face of the NPC and is sufficient for cell viability, demonstrating that NPC localization of Dbp5 is the essential feature for mRNP remodeling, separable from other subcellular functions.","method":"Proximity ligation assay, co-immunoprecipitation, Dbp5-Nup159 fusion genetics, in vivo mRNA export assays","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 — proximity ligation plus genetic fusion rescue; single lab","pmids":["33002012"],"is_preprint":false},{"year":2021,"finding":"DDX19B tethers the CBC-dependent translation initiation factor CTIF to the perinuclear region in a translationally incompetent manner; DDX19B hands CTIF over to CBP80 upon mRNA export, enabling CBC-dependent translation locally at the perinuclear region; disrupting the CTIF-DDX19B interaction causes uncontrolled translation throughout the cytosol and dysregulates nonsense-mediated mRNA decay.","method":"Co-immunoprecipitation, fluorescence microscopy, siRNA knockdown, dominant-negative mutants, NMD reporter assays","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus functional knockdown and reporter assays; single lab","pmids":["34232997"],"is_preprint":false},{"year":2022,"finding":"DDX19 (DDX19A and DDX19B) is SUMOylated at lysine 26; this modification enhances DDX19's interaction with Gle1; a SUMOylation-defective K26R mutant of human DDX19B fails to fully rescue mRNA export defects caused by DDX19 depletion.","method":"In vivo SUMOylation assay, co-immunoprecipitation, siRNA knockdown, rescue experiments with K26R mutant","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — modification site identified with functional mutant rescue; single lab","pmids":["35080244"],"is_preprint":false},{"year":2022,"finding":"Gle1 activates Dbp5/DDX19B by two mechanisms: (1) thermodynamic coupling between Gle1 and ATP binding causes Gle1 to bind Dbp5-ATP >100-fold more tightly than other nucleotide states, slowing ATP dissociation; (2) Gle1 accelerates rate-limiting Pi release ~20-fold, maintaining Pi release as the rate-limiting step during activated cycling.","method":"Kinetic and equilibrium fluorescence assays, in vitro ATPase reconstitution","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — detailed mechanistic kinetics with multiple quantitative assays establishing two distinct activation mechanisms","pmids":["35286399"],"is_preprint":false},{"year":2024,"finding":"Dbp5/DDX19B directly binds tRNA and functions in tRNA export parallel to the canonical Los1 pathway; tRNA direct binding does not activate Dbp5 ATPase activity, but tRNA acts synergistically with Gle1 to fully activate Dbp5; Dbp5 is recruited to tRNA independently of Los1, Msn5, or Mex67; functional ATPase cycle and Gle1 binding are required for tRNA export.","method":"Co-immunoprecipitation, dominant-negative overexpression, genetic epistasis, in vitro ATPase assays with tRNA","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro biochemistry plus in vivo genetics; single lab","pmids":["38189406"],"is_preprint":false}],"current_model":"DDX19B (human Dbp5) is a DEAD-box RNA-dependent ATPase anchored to cytoplasmic NPC filaments via NUP214; at the NPC its ATPase cycle is spatially regulated by a Nup42–Gle1–InsP6 activating complex (Gle1 couples ATP binding and accelerates Pi release while Nup159 modulates Gle1 release from ADP-bound DDX19B), an N-terminal autoregulatory helix, and SUMOylation at K26; in the ADP-bound state DDX19B remodels mRNPs by displacing Nab2, NXF1/Mex67 and other RNA-binding proteins from exiting transcripts to impose directionality on mRNA export, while also tethering the translation initiation factor CTIF at the perinuclear region for local CBC-dependent translation; beyond mRNA, DDX19B participates in translation termination (stabilizing pre-termination complexes and delivering eRF1), tRNA export (requiring ATPase activity and Gle1), pre-ribosomal subunit export (ATPase-independent capture), nuclear import of MKL1 (via RNA-binding-dependent conformational modulation), and ATR/Chk1-dependent nuclear relocalization to resolve R-loops at replication-transcription conflicts; additionally, DDX19B negatively regulates innate immune signaling by recruiting Lamtor2 to disrupt TBK1/IKKε–IRF3 interactions and promote TBK1/IKKε degradation."},"narrative":{"teleology":[{"year":1999,"claim":"Establishing DDX19B as an NPC-associated ATPase required for mRNA export resolved how directional transport is powered at the nuclear pore: hDbp5 localizes to cytoplasmic NPC fibrils via NUP214, and a DEAD-box mutation dominantly blocks mRNA export.","evidence":"Co-IP, immunoelectron microscopy, and dominant-negative microinjection in Xenopus oocytes","pmids":["10428971"],"confidence":"High","gaps":["Mechanism of mRNP remodeling unknown","Regulatory cofactors unidentified","Structural basis for NUP214 interaction unresolved"]},{"year":2004,"claim":"Determining the crystal structure of the Nup159 β-propeller bound to Dbp5 established the structural basis for NPC tethering and showed it is essential for mRNA export in vivo.","evidence":"X-ray crystallography (2.5 Å) with structure-guided mutagenesis and in vivo export assays in yeast","pmids":["15574330"],"confidence":"High","gaps":["Nucleotide-state dependence of docking unclear","How tethering translates to remodeling activity unknown"]},{"year":2006,"claim":"Identification of Gle1–InsP6 as a direct activating complex for DDX19B's ATPase activity revealed the spatial regulatory logic: cofactors concentrated at the NPC stimulate the enzyme precisely where mRNP remodeling must occur.","evidence":"In vitro ATPase kinetics, genetic suppression, and in vivo mRNA export assays in two independent studies","pmids":["16783363","16783364"],"confidence":"High","gaps":["Kinetic mechanism of activation (which step accelerated) unresolved","InsP6 binding site on complex unknown"]},{"year":2007,"claim":"Demonstrating that DDX19B displaces the RNA-binding protein Nab2 specifically in its ADP-bound state established the remodeling mechanism: ADP binding, not ATP hydrolysis per se, drives the conformational change that strips export factors from mRNA.","evidence":"In vitro RNP remodeling assays with nucleotide-state mutants plus in vivo genetics","pmids":["18082609"],"confidence":"High","gaps":["Full spectrum of displaced RNA-binding proteins unknown","Whether remodeling is processive or single-turnover unclear"]},{"year":2007,"claim":"Discovery that Dbp5 physically interacts with eRF1 and is required for stop-codon recognition expanded its functional repertoire beyond mRNA export to translation termination.","evidence":"Co-IP, genetic epistasis with eRF1/eRF3/Pab1, helicase-mutant analysis, and in vivo termination assays in yeast","pmids":["17272721"],"confidence":"High","gaps":["Whether mRNA export and termination functions are mechanistically coupled unknown","Mammalian reconstitution lacking at this stage"]},{"year":2009,"claim":"A series of crystal structures of human DDX19B in multiple nucleotide/ligand states revealed mutually exclusive RNA and NUP214 binding, the N-terminal autoregulatory helix, and the Gle1-binding interface, providing an integrated structural framework for its catalytic cycle.","evidence":"X-ray crystallography of DDX19B–RNA–AMPPNP, DDX19B–NUP214, DDX19B open/closed states, and DDX19B C-terminal domain, all with biochemical and mutagenesis validation","pmids":["19219046","19244245","19208808","19805289"],"confidence":"High","gaps":["Full reconstituted NPC-like complex structure lacking","How N-terminal helix regulation integrates with Gle1 activation kinetically unclear"]},{"year":2011,"claim":"Reconstitution of the nucleotide cycle showed that Nup159 promotes ADP release (later refined to Gle1 dissociation) while Gle1–IP6 primes ATP binding, defining the ordered cofactor logic at the NPC; FRAP revealed sub-second dynamic NPC association of DDX19B.","evidence":"In vitro nucleotide-binding/release assays, Dbp5-Nup159 bypass mutants, FRAP in yeast and human cells","pmids":["21576266","21576265"],"confidence":"High","gaps":["Exact role of Nup159 (nucleotide exchange vs. Gle1 release) debated","Single-molecule kinetics at NPCs lacking"]},{"year":2015,"claim":"Detailed pre-steady-state kinetics quantified the DDX19B ATPase cycle — weak ATP binding (~4 mM Kd), 10-fold tighter ADP binding, and rate-limiting Pi release accelerated ~20-fold by RNA — establishing the biophysical basis for cofactor regulation.","evidence":"Stopped-flow kinetics and equilibrium binding assays","pmids":["26730886"],"confidence":"High","gaps":["Gle1's kinetic mechanism not yet quantified at this stage","Physiological nucleotide concentrations not modeled"]},{"year":2015,"claim":"Identification of DDX19B's role in MKL1 nuclear import — requiring RNA binding but not helicase or NPC-binding activities — established the first export-independent nuclear import function for this helicase.","evidence":"siRNA knockdown, domain-mutant rescue, Co-IP, and nuclear import assays in mammalian cells","pmids":["25585691"],"confidence":"Medium","gaps":["Mechanism by which RNA binding alters MKL1 conformation unresolved","Not independently replicated","Whether this function is conserved in yeast unknown"]},{"year":2016,"claim":"Showing that DDX19B is required for pre-ribosomal subunit export but in an ATPase-independent manner distinguished this function mechanistically from mRNA export, suggesting a scaffolding or capture role at the NPC.","evidence":"Yeast temperature-sensitive mutants, ATPase-deficient alleles, Co-IP with Nmd3, fluorescence microscopy","pmids":["26872259"],"confidence":"Medium","gaps":["Whether DDX19B directly contacts pre-ribosomal particles or acts indirectly unknown","Human validation lacking"]},{"year":2017,"claim":"Reconstitution with mammalian DDX19 confirmed its role in translation termination — increasing termination complex formation and peptide release — extending the yeast findings and showing nucleotide-dependent association with pre-termination complexes.","evidence":"Reconstituted mammalian in vitro translation system with sucrose gradient sedimentation","pmids":["28180304"],"confidence":"High","gaps":["Structural basis for DDX19–ribosome interaction unknown","Whether mRNA export and termination pools of DDX19B are distinct in vivo unclear"]},{"year":2017,"claim":"Discovery that DDX19B relocalizes from NPCs to the nucleus under replication stress via ATR/Chk1 phosphorylation to resolve R-loops established a DNA damage response function: Chk1-phosphorylation disrupts NUP214 binding, and nuclear DDX19B's helicase activity unwinds DNA:RNA hybrids.","evidence":"Live-cell imaging, R-loop immunofluorescence, in vitro helicase assay, phosphorylation mutants, DNA fiber assays","pmids":["28314779"],"confidence":"High","gaps":["Specific Chk1 phosphorylation site(s) not fully mapped","Whether R-loop resolution is a direct helicase activity on DNA:RNA hybrids in vivo confirmed only indirectly"]},{"year":2017,"claim":"Establishing that Nup42 is required for Gle1-mediated DDX19B activation — forming a Nup42–Gle1–Dbp5 trimeric complex with InsP6 — completed the NPC-resident activating module architecture.","evidence":"In vitro ATPase reconstitution with yeast and human proteins, Co-IP, mRNA export assays","pmids":["28869701"],"confidence":"High","gaps":["Structural model of complete trimeric activating complex lacking","Stoichiometry at NPCs unknown"]},{"year":2018,"claim":"Revised kinetic analysis showed Nup159 does not accelerate ADP release but instead weakens the Gle1–ADP–Dbp5 ternary complex ~18-fold, redefining Nup159's role as facilitating Gle1 recycling rather than acting as a nucleotide exchange factor.","evidence":"Stopped-flow kinetics and fluorescence equilibrium binding assays","pmids":["29782832"],"confidence":"High","gaps":["Whether Nup159 also modulates other steps in the full NPC context unknown","Reconciliation with the 2011 model not fully settled"]},{"year":2019,"claim":"Discovery that DDX19B negatively regulates type I interferon production — by recruiting Lamtor2 to disrupt TBK1/IKKε–IRF3 interactions and promote kinase degradation — revealed an innate immune signaling function validated by knockout mice with augmented IFN production.","evidence":"Reciprocal Co-IP, TALEN-generated knockout mice, virus infection assays","pmids":["30699353"],"confidence":"High","gaps":["Whether this immune function requires ATPase or RNA-binding activities unknown","Mechanism of Lamtor2 recruitment unclear"]},{"year":2019,"claim":"Identification of an N-terminal Xpo1-dependent NES in Dbp5 and separation-of-function alleles showing that nuclear shuttling is dispensable for mRNA export but specifically required for tRNA export established tRNA export as a distinct DDX19B function.","evidence":"Systematic alanine scanning mutagenesis (456 viable mutants), tRNA export assays in yeast","pmids":["31453808"],"confidence":"Medium","gaps":["Mechanism of DDX19B action on tRNA substrates unknown at this point","Human tRNA export role not tested"]},{"year":2021,"claim":"Demonstrating that DDX19B tethers CTIF at the perinuclear region in a translationally incompetent state and hands it to CBP80 upon mRNA export established DDX19B as a spatial organizer of CBC-dependent translation and nonsense-mediated decay.","evidence":"Co-IP, fluorescence microscopy, siRNA knockdown, dominant-negative mutants, NMD reporter assays","pmids":["34232997"],"confidence":"Medium","gaps":["Structural basis for DDX19B–CTIF interaction unknown","Whether this mechanism operates on all or a subset of mRNAs unclear"]},{"year":2022,"claim":"Quantitative kinetic dissection showed Gle1 activates DDX19B by two mechanisms — thermodynamic coupling that stabilizes the ATP-bound state (>100-fold preferential binding) and acceleration of rate-limiting Pi release (~20-fold) — providing the definitive kinetic model for the activating complex.","evidence":"Kinetic and equilibrium fluorescence assays, in vitro ATPase reconstitution","pmids":["35286399"],"confidence":"High","gaps":["How InsP6 and Nup42 quantitatively modulate these two mechanisms not fully integrated","In vivo validation of kinetic parameters lacking"]},{"year":2022,"claim":"Identification of SUMOylation at K26 as a modification that enhances DDX19B–Gle1 interaction and is required for full mRNA export rescue added a post-translational regulatory layer to the ATPase cycle.","evidence":"In vivo SUMOylation assay, Co-IP, siRNA rescue with K26R mutant","pmids":["35080244"],"confidence":"Medium","gaps":["SUMOylation dynamics and triggering signals unknown","Whether K26 SUMOylation affects other DDX19B functions (termination, R-loop resolution) untested"]},{"year":2024,"claim":"Direct demonstration that Dbp5 binds tRNA and functions in tRNA export parallel to Los1 — with tRNA synergizing with Gle1 to fully activate Dbp5 ATPase — defined the molecular mechanism for the tRNA export role first genetically identified in 2019.","evidence":"Co-IP, in vitro ATPase assays with tRNA, dominant-negative overexpression, genetic epistasis in yeast","pmids":["38189406"],"confidence":"Medium","gaps":["Whether DDX19B remodels tRNP complexes analogously to mRNP remodeling unknown","Human tRNA export function not yet demonstrated"]},{"year":null,"claim":"Key unresolved questions include the structural basis for the complete NPC-resident DDX19B activation complex in situ, how the multiple functions (mRNA export, tRNA export, translation termination, R-loop resolution, immune signaling) are partitioned among cellular pools, and whether substrate-specific cofactor interactions determine functional selectivity.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No cryo-EM or cryo-ET structure of DDX19B at the intact NPC","Partitioning of DDX19B pools among its many functions not quantified","Regulation by SUMOylation and Chk1 phosphorylation not integrated into a unified model"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,2,3,14,26]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[6,7,15,27]},{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[18]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[21]}],"localization":[{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[0,1,8,12,23]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[18]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[17]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,2,4,11,19,25]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[5,17]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[16,22,27]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[18]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[21]}],"complexes":["Gle1–Nup42–InsP6 activation complex","NUP214–DDX19B NPC docking complex"],"partners":["NUP214","GLE1","NUP42","RBM15","CTIF","ERF1","SLIP1","LAMTOR2"],"other_free_text":[]},"mechanistic_narrative":"DDX19B is a DEAD-box RNA-dependent ATPase that functions as the principal mRNP remodeling enzyme at the cytoplasmic face of the nuclear pore complex, imposing directionality on mRNA export by displacing RNA-binding proteins such as Nab2 and Mex67/NXF1 from exiting transcripts in its ADP-bound state [PMID:18082609, PMID:33002012]. Its ATPase cycle is spatially regulated at the NPC through anchoring to NUP214, activation by a Gle1–InsP6–Nup42 complex that couples ATP binding and accelerates rate-limiting Pi release, and an N-terminal autoregulatory helix that modulates interdomain conformation [PMID:10428971, PMID:16783363, PMID:28869701, PMID:19244245, PMID:35286399]. Beyond mRNA export, DDX19B participates in translation termination by stabilizing pre-termination complexes and delivering eRF1, in tRNA export through a Gle1-dependent ATPase cycle, in ATR/Chk1-directed nuclear relocalization to resolve R-loops at replication–transcription conflicts, and in spatial control of CBC-dependent translation by tethering CTIF at the perinuclear region [PMID:17272721, PMID:28180304, PMID:38189406, PMID:28314779, PMID:34232997]. DDX19B also negatively regulates type I interferon signaling by recruiting Lamtor2 to disrupt TBK1/IKKε–IRF3 interactions and promote kinase degradation [PMID:30699353]."},"prefetch_data":{"uniprot":{"accession":"Q9UMR2","full_name":"ATP-dependent RNA helicase DDX19B","aliases":["DEAD box RNA helicase DEAD5","DEAD box protein 19B"],"length_aa":479,"mass_kda":53.9,"function":"ATP-dependent RNA helicase involved in mRNA export from the nucleus (PubMed:10428971). Rather than unwinding RNA duplexes, DDX19B functions as a remodeler of ribonucleoprotein particles, whereby proteins bound to nuclear mRNA are dissociated and replaced by cytoplasmic mRNA binding proteins (PubMed:10428971)","subcellular_location":"Cytoplasm; Nucleus, nucleoplasm","url":"https://www.uniprot.org/uniprotkb/Q9UMR2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DDX19B","classification":"Not Classified","n_dependent_lines":45,"n_total_lines":1208,"dependency_fraction":0.037251655629139076},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/DDX19B","total_profiled":1310},"omim":[{"mim_id":"621395","title":"DEAD-BOX HELICASE 19A; DDX19A","url":"https://www.omim.org/entry/621395"},{"mim_id":"605812","title":"DEAD-BOX HELICASE 19B; DDX19B","url":"https://www.omim.org/entry/605812"},{"mim_id":"602666","title":"MYOSIN XVA; MYO15A","url":"https://www.omim.org/entry/602666"},{"mim_id":"600316","title":"DEAFNESS, AUTOSOMAL RECESSIVE 3; DFNB3","url":"https://www.omim.org/entry/600316"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Nucleoplasm","reliability":"Uncertain"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/DDX19B"},"hgnc":{"alias_symbol":["DBP5"],"prev_symbol":["DDX19"]},"alphafold":{"accession":"Q9UMR2","domains":[{"cath_id":"3.40.50.300","chopping":"56-296","consensus_level":"high","plddt":88.3448,"start":56,"end":296},{"cath_id":"3.40.50.300","chopping":"306-477","consensus_level":"high","plddt":87.0093,"start":306,"end":477}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UMR2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UMR2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UMR2-F1-predicted_aligned_error_v6.png","plddt_mean":81.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DDX19B","jax_strain_url":"https://www.jax.org/strain/search?query=DDX19B"},"sequence":{"accession":"Q9UMR2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UMR2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UMR2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UMR2"}},"corpus_meta":[{"pmid":"16783363","id":"PMC_16783363","title":"Inositol 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\"Co-immunoprecipitation, immunoelectron microscopy, direct binding assays, dominant-negative microinjection in Xenopus oocytes\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal binding assays, in vivo localization, functional microinjection; independently replicated across yeast and human systems\",\n      \"pmids\": [\"10428971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The N-terminal beta-propeller domain of yeast Nup159 (human NUP214 ortholog) directly binds Dbp5/DDX19; structure-based mutations in a conserved loop abolish Dbp5 binding in vitro, mislocalize Dbp5 from the NPC in vivo, and block mRNA export, demonstrating that NPC tethering of Dbp5 via Nup159 is essential for mRNA export.\",\n      \"method\": \"X-ray crystallography (2.5 Å), in vitro binding assays, structure-guided mutagenesis, in vivo mRNA export assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with mutagenesis and in vivo functional validation\",\n      \"pmids\": [\"15574330\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Inositol hexakisphosphate (InsP6) and the NPC-associated protein Gle1 together stimulate the RNA-dependent ATPase activity of Dbp5/DDX19B; InsP6 requires both Dbp5 and Gle1 for maximal binding and lowers the RNA concentration needed for half-maximal ATPase activity; overexpression of DBP5 suppresses mRNA export defects caused by InsP6/Gle1 loss.\",\n      \"method\": \"In vitro ATPase kinetic assays, genetic suppression, in vivo mRNA export assays\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with kinetic analysis, corroborated by independent parallel study (PMID:16783364)\",\n      \"pmids\": [\"16783363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Gle1 is a direct cellular activator of Dbp5/DDX19B: Gle1 alone stimulates Dbp5 RNA binding and ATP hydrolysis, and InsP6 potentiates Gle1-mediated activation; a Gle1 point mutant deficient for Dbp5 stimulation in vitro shows mRNA export defects in vivo; dominant suppressor mutations in DBP5 and GLE1 mimic InsP6 effects in vitro.\",\n      \"method\": \"In vitro ATPase and RNA-binding assays, dominant suppressor mutagenesis, in vivo mRNA export assays\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with mutagenesis and in vivo correlation; simultaneous independent replication (PMID:16783363)\",\n      \"pmids\": [\"16783364\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Dbp5/DDX19B acts as an RNP remodeling protein at the NPC by displacing the RNA-binding protein Nab2 from mRNA; this remodeling requires the ADP-bound (not ATP-bound) form of Dbp5, indicating that ADP binding rather than ATP hydrolysis drives the conformational change for protein displacement.\",\n      \"method\": \"In vitro RNP remodeling assays, nucleotide-state-specific mutants, in vivo genetic analysis of nab2 and dbp5 mutants\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with nucleotide mutants plus in vivo genetic validation\",\n      \"pmids\": [\"18082609\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Dbp5/DDX19B functions in translation termination in S. cerevisiae: it physically interacts with release factor eRF1, genetically interacts with eRF1, eRF3, and Pab1, and its helicase activity is required for efficient stop-codon recognition and for recruitment of eRF3 into termination complexes.\",\n      \"method\": \"Co-immunoprecipitation, genetic interaction analysis, helicase-activity mutants, in vivo translation termination assays\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus genetic epistasis plus functional mutant analysis; highly cited foundational study\",\n      \"pmids\": [\"17272721\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structures of human DDX19B bound to RNA+AMPPNP and bound to NUP214 reveal that RNA binding and NUP214 binding to DDX19B are mutually exclusive; NUP214 decreases both RNA binding and ATPase activities of DDX19B; interactions are mediated by conserved residues.\",\n      \"method\": \"X-ray crystallography, in vitro ATPase and RNA-binding assays, mutagenesis\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures with biochemical validation and mutagenesis in human protein\",\n      \"pmids\": [\"19219046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structures of human DDX19B in RNA-bound/prehydrolysis (closed cleft) and free/posthydrolysis (open cleft) states reveal an N-terminal alpha-helix that inserts between the two conserved RecA-like domains in the open conformation to negatively autoregulate ATPase activity; biochemical data confirm this N-terminal autoregulatory function.\",\n      \"method\": \"X-ray crystallography, biochemical ATPase assays, truncation analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures in two functional states with biochemical validation\",\n      \"pmids\": [\"19244245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of the Nup214 N-terminal domain in complex with DDX19B (ADP-bound state) at 2.5 Å; the interaction surfaces show opposing surface potentials (helicase positive, Nup214 negative); binding interfaces are evolutionarily conserved, providing a structural basis for NPC docking of DDX19B.\",\n      \"method\": \"X-ray crystallography (2.5 Å), structural and biochemical analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure of complex with functional interpretation\",\n      \"pmids\": [\"19208808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of the C-terminal domain of Dbp5/DDX19B (1.8 Å) reveals a RecA-like fold with a unique C-terminal alpha-helix and loop; structure-guided mutagenesis of conserved charged surface residues identifies the Gle1-binding interface; mutations that weaken Gle1 binding and ATPase stimulation in vitro are lethal in vivo.\",\n      \"method\": \"X-ray crystallography, structure-guided mutagenesis, in vitro ATPase assays, yeast viability assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus mutagenesis with in vitro and in vivo correlation\",\n      \"pmids\": [\"19805289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"RBM15 directly binds human DBP5 and facilitates DBP5's contact with mRNA in vivo; RBM15 co-localizes with DBP5 and NXF1 at the nuclear envelope; silencing RBM15 leads to cytoplasmic depletion and nuclear accumulation of mRNA, indicating RBM15 promotes recognition of NXF1-mRNP by DBP5 at the NPC.\",\n      \"method\": \"Co-immunoprecipitation, RNA immunoprecipitation, siRNA knockdown, fluorescence microscopy\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus in vivo functional knockdown; single lab study\",\n      \"pmids\": [\"19786495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Nup159 functions as an ADP release factor for Dbp5/DDX19B: in vitro reconstitution assays show Nup159 is specifically required for ADP release from Dbp5, while Gle1-IP6 stimulates ATP binding to prime Dbp5 for RNA loading; a dbp5 mutant with reduced ADP binding bypasses the need for Nup159 interaction in vivo.\",\n      \"method\": \"In vitro nucleotide-binding and release assays, reconstitution, in vivo mutant analysis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with multiple biochemical assays plus in vivo rescue genetics\",\n      \"pmids\": [\"21576266\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ATP binding and hydrolysis are required for efficient Dbp5 association with NPCs; RNA-binding-deficient Dbp5 mutants are dominant-negative for mRNA export by competing with wild-type Dbp5 for Gle1 at NPCs; FRAP shows Dbp5 associates with NPCs very dynamically (~<1 sec); Dbp5-Gle1 interaction can be independent of Nup159.\",\n      \"method\": \"Mutant analysis, dominant-negative assays, FRAP (yeast and human cells), in vivo mRNA export assays\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (FRAP, genetic, functional) in two organisms\",\n      \"pmids\": [\"21576265\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"DBP5/DDX19B contains a SLIP1-binding motif (SBM) and directly interacts with SLIP1 (a MIF4G-domain protein involved in translation initiation); crystal structure of SLIP1 bound to the DBP5 SBM was determined at 3.25 Å, identifying a physical link between the mRNA export factor and translational machinery.\",\n      \"method\": \"X-ray crystallography (3.25 Å), pull-down assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 structure + Tier 3 pull-down; functional consequence not fully established\",\n      \"pmids\": [\"23804756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Kinetic analysis of the Dbp5/DDX19B ATPase cycle shows that ATP binds weakly (KT ~4 mM) while ADP binds ~10-fold more tightly; RNA increases kcat and rate-limiting Pi release ~20-fold but Pi release remains rate-limiting even with RNA; identifying RNA binding and Pi release as critical biochemical transitions in the Dbp5 cycle.\",\n      \"method\": \"Stopped-flow kinetics, equilibrium binding assays, in vitro ATPase assays\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — detailed kinetic reconstitution with multiple methods\",\n      \"pmids\": [\"26730886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Ddx19/Dbp5 is required for nuclear import of the transcriptional coactivator MKL1; this function is distinct from its mRNA export role; RNA-binding activity of Ddx19 (but not helicase or NPC-binding activities) is required; Ddx19 modulates the conformation of MKL1 to facilitate its interaction with Importin-β.\",\n      \"method\": \"siRNA knockdown, domain-mutant rescue assays, co-immunoprecipitation, nuclear import assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with specific phenotype plus Co-IP and domain mapping; single lab\",\n      \"pmids\": [\"25585691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Dbp5/DDX19B is required for nuclear export of both pre-ribosomal subunits in yeast; genetic and physical interactions occur with the ribosomal transport factor Nmd3; however, unlike mRNA export, ATPase-deficient dbp5 mutants and gle1 mutants do not block ribosomal export, indicating DDX19B supports ribosomal transport through NPC localization/capture rather than ATPase-dependent remodeling.\",\n      \"method\": \"Yeast temperature-sensitive mutants, co-immunoprecipitation, fluorescence microscopy, ATPase-deficient mutants\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with multiple mutant alleles plus Co-IP; single lab\",\n      \"pmids\": [\"26872259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"DDX19 (mammalian Dbp5 ortholog) participates in translation termination: it associates with translating ribosome fractions, interacts with pre-termination complexes in a nucleotide-dependent manner, increases termination complex formation and peptide release by eukaryotic release factors, and stabilizes ribosome complexes with elongation factors eEF1 and eEF2.\",\n      \"method\": \"Reconstituted mammalian in vitro translation system, sucrose gradient sedimentation, eRF1(AGQ) and non-hydrolysable GTP inhibitor assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro translation with multiple functional assays in human DDX19\",\n      \"pmids\": [\"28180304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Ddx19 (human DDX19B ortholog) relocalizes from the nucleopore to the nucleus upon DNA damage or replication stress in an ATR/Chk1-dependent manner; nuclear Ddx19 resolves R-loops (DNA:RNA hybrids) via its helicase activity in vitro; mutation of a Chk1-phosphorylated residue disrupts Ddx19 interaction with Nup214 and allows nuclear relocalization; Ddx19 depletion causes R-loop accumulation, DNA damage, and replication fork progression defects.\",\n      \"method\": \"Live-cell imaging, R-loop immunofluorescence, in vitro helicase assay, ATR/Chk1 inhibitors, phosphorylation mutants, siRNA knockdown, DNA fiber assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods including in vitro helicase reconstitution, live imaging, and genetics; single lab but comprehensive\",\n      \"pmids\": [\"28314779\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Nup42 is required for efficient Dbp5/DDX19B activation: the Nup42 C-terminal domain binds Gle1/hGle1B at a site distinct from the Gle1-Dbp5 interface; a nup42-CTD/gle1-CTD/Dbp5 trimeric complex forms in the presence of IP6; deletion of NUP42 abrogates Gle1-Dbp5 interaction; Nup42 and IP6 stimulate Gle1/hGle1B activation of both yeast Dbp5 and human DDX19B in vitro in a non-additive manner.\",\n      \"method\": \"In vitro ATPase assays with recombinant proteins, co-immunoprecipitation, yeast and human cell mRNA export assays, structure-function mutagenesis\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro reconstitution with both yeast and human proteins plus in vivo functional correlation\",\n      \"pmids\": [\"28869701\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Nup159 does not accelerate ADP release from Dbp5/DDX19B; instead Gle1 slows ADP release; Mg2+ slows both ADP and ATP release and increases their affinities; Nup159 reduces Gle1-ADP-Dbp5 interaction ~18-fold, suggesting Nup159 aids Gle1 dissociation from ADP-bound Dbp5 rather than acting as a nucleotide exchange factor.\",\n      \"method\": \"Stopped-flow kinetics, fluorescence equilibrium binding assays, in vitro biochemical reconstitution\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — detailed kinetic analysis contradicting prior model, with multiple quantitative assays\",\n      \"pmids\": [\"29782832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"DDX19B is a negative regulator of type I interferon production: it inhibits TBK1- and IKKε-mediated phosphorylation of IRF3 by disrupting TBK1/IKKε-IRF3 interactions; DDX19B recruits Lamtor2 to form a TBK1-IKKε-Lamtor2-DDX19-IRF3 complex that promotes TBK1 and IKKε degradation; Ddx19 knockout mice show augmented type I IFN production.\",\n      \"method\": \"Ectopic overexpression, siRNA knockdown, co-immunoprecipitation, TALEN-generated knockout mice, virus infection assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, KO mouse, and functional assays; multiple orthogonal methods\",\n      \"pmids\": [\"30699353\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Dbp5/DDX19B contains an N-terminal Xpo1-dependent nuclear export signal; disruptions in Dbp5 nucleocytoplasmic transport result in tRNA export defects rather than mRNA export defects, indicating nuclear shuttling of Dbp5 is not essential for mRNP export but is specifically required for tRNA export.\",\n      \"method\": \"Alanine scanning mutagenesis (456 viable mutants), GFP reporter, genetic analysis, tRNA export assays in yeast\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — systematic mutagenesis with separation-of-function alleles; single lab\",\n      \"pmids\": [\"31453808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Dbp5 associates in close proximity with both Mex67 (mRNA export receptor) and Nab2 in a cellular complex; fusion of Dbp5 to Nup159 anchors it at the cytoplasmic face of the NPC and is sufficient for cell viability, demonstrating that NPC localization of Dbp5 is the essential feature for mRNP remodeling, separable from other subcellular functions.\",\n      \"method\": \"Proximity ligation assay, co-immunoprecipitation, Dbp5-Nup159 fusion genetics, in vivo mRNA export assays\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proximity ligation plus genetic fusion rescue; single lab\",\n      \"pmids\": [\"33002012\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"DDX19B tethers the CBC-dependent translation initiation factor CTIF to the perinuclear region in a translationally incompetent manner; DDX19B hands CTIF over to CBP80 upon mRNA export, enabling CBC-dependent translation locally at the perinuclear region; disrupting the CTIF-DDX19B interaction causes uncontrolled translation throughout the cytosol and dysregulates nonsense-mediated mRNA decay.\",\n      \"method\": \"Co-immunoprecipitation, fluorescence microscopy, siRNA knockdown, dominant-negative mutants, NMD reporter assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus functional knockdown and reporter assays; single lab\",\n      \"pmids\": [\"34232997\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DDX19 (DDX19A and DDX19B) is SUMOylated at lysine 26; this modification enhances DDX19's interaction with Gle1; a SUMOylation-defective K26R mutant of human DDX19B fails to fully rescue mRNA export defects caused by DDX19 depletion.\",\n      \"method\": \"In vivo SUMOylation assay, co-immunoprecipitation, siRNA knockdown, rescue experiments with K26R mutant\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — modification site identified with functional mutant rescue; single lab\",\n      \"pmids\": [\"35080244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Gle1 activates Dbp5/DDX19B by two mechanisms: (1) thermodynamic coupling between Gle1 and ATP binding causes Gle1 to bind Dbp5-ATP >100-fold more tightly than other nucleotide states, slowing ATP dissociation; (2) Gle1 accelerates rate-limiting Pi release ~20-fold, maintaining Pi release as the rate-limiting step during activated cycling.\",\n      \"method\": \"Kinetic and equilibrium fluorescence assays, in vitro ATPase reconstitution\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — detailed mechanistic kinetics with multiple quantitative assays establishing two distinct activation mechanisms\",\n      \"pmids\": [\"35286399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Dbp5/DDX19B directly binds tRNA and functions in tRNA export parallel to the canonical Los1 pathway; tRNA direct binding does not activate Dbp5 ATPase activity, but tRNA acts synergistically with Gle1 to fully activate Dbp5; Dbp5 is recruited to tRNA independently of Los1, Msn5, or Mex67; functional ATPase cycle and Gle1 binding are required for tRNA export.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative overexpression, genetic epistasis, in vitro ATPase assays with tRNA\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro biochemistry plus in vivo genetics; single lab\",\n      \"pmids\": [\"38189406\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DDX19B (human Dbp5) is a DEAD-box RNA-dependent ATPase anchored to cytoplasmic NPC filaments via NUP214; at the NPC its ATPase cycle is spatially regulated by a Nup42–Gle1–InsP6 activating complex (Gle1 couples ATP binding and accelerates Pi release while Nup159 modulates Gle1 release from ADP-bound DDX19B), an N-terminal autoregulatory helix, and SUMOylation at K26; in the ADP-bound state DDX19B remodels mRNPs by displacing Nab2, NXF1/Mex67 and other RNA-binding proteins from exiting transcripts to impose directionality on mRNA export, while also tethering the translation initiation factor CTIF at the perinuclear region for local CBC-dependent translation; beyond mRNA, DDX19B participates in translation termination (stabilizing pre-termination complexes and delivering eRF1), tRNA export (requiring ATPase activity and Gle1), pre-ribosomal subunit export (ATPase-independent capture), nuclear import of MKL1 (via RNA-binding-dependent conformational modulation), and ATR/Chk1-dependent nuclear relocalization to resolve R-loops at replication-transcription conflicts; additionally, DDX19B negatively regulates innate immune signaling by recruiting Lamtor2 to disrupt TBK1/IKKε–IRF3 interactions and promote TBK1/IKKε degradation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"DDX19B is a DEAD-box RNA-dependent ATPase that functions as the principal mRNP remodeling enzyme at the cytoplasmic face of the nuclear pore complex, imposing directionality on mRNA export by displacing RNA-binding proteins such as Nab2 and Mex67/NXF1 from exiting transcripts in its ADP-bound state [PMID:18082609, PMID:33002012]. Its ATPase cycle is spatially regulated at the NPC through anchoring to NUP214, activation by a Gle1–InsP6–Nup42 complex that couples ATP binding and accelerates rate-limiting Pi release, and an N-terminal autoregulatory helix that modulates interdomain conformation [PMID:10428971, PMID:16783363, PMID:28869701, PMID:19244245, PMID:35286399]. Beyond mRNA export, DDX19B participates in translation termination by stabilizing pre-termination complexes and delivering eRF1, in tRNA export through a Gle1-dependent ATPase cycle, in ATR/Chk1-directed nuclear relocalization to resolve R-loops at replication–transcription conflicts, and in spatial control of CBC-dependent translation by tethering CTIF at the perinuclear region [PMID:17272721, PMID:28180304, PMID:38189406, PMID:28314779, PMID:34232997]. DDX19B also negatively regulates type I interferon signaling by recruiting Lamtor2 to disrupt TBK1/IKKε–IRF3 interactions and promote kinase degradation [PMID:30699353].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Establishing DDX19B as an NPC-associated ATPase required for mRNA export resolved how directional transport is powered at the nuclear pore: hDbp5 localizes to cytoplasmic NPC fibrils via NUP214, and a DEAD-box mutation dominantly blocks mRNA export.\",\n      \"evidence\": \"Co-IP, immunoelectron microscopy, and dominant-negative microinjection in Xenopus oocytes\",\n      \"pmids\": [\"10428971\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of mRNP remodeling unknown\", \"Regulatory cofactors unidentified\", \"Structural basis for NUP214 interaction unresolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Determining the crystal structure of the Nup159 β-propeller bound to Dbp5 established the structural basis for NPC tethering and showed it is essential for mRNA export in vivo.\",\n      \"evidence\": \"X-ray crystallography (2.5 Å) with structure-guided mutagenesis and in vivo export assays in yeast\",\n      \"pmids\": [\"15574330\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Nucleotide-state dependence of docking unclear\", \"How tethering translates to remodeling activity unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identification of Gle1–InsP6 as a direct activating complex for DDX19B's ATPase activity revealed the spatial regulatory logic: cofactors concentrated at the NPC stimulate the enzyme precisely where mRNP remodeling must occur.\",\n      \"evidence\": \"In vitro ATPase kinetics, genetic suppression, and in vivo mRNA export assays in two independent studies\",\n      \"pmids\": [\"16783363\", \"16783364\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinetic mechanism of activation (which step accelerated) unresolved\", \"InsP6 binding site on complex unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrating that DDX19B displaces the RNA-binding protein Nab2 specifically in its ADP-bound state established the remodeling mechanism: ADP binding, not ATP hydrolysis per se, drives the conformational change that strips export factors from mRNA.\",\n      \"evidence\": \"In vitro RNP remodeling assays with nucleotide-state mutants plus in vivo genetics\",\n      \"pmids\": [\"18082609\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full spectrum of displaced RNA-binding proteins unknown\", \"Whether remodeling is processive or single-turnover unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Discovery that Dbp5 physically interacts with eRF1 and is required for stop-codon recognition expanded its functional repertoire beyond mRNA export to translation termination.\",\n      \"evidence\": \"Co-IP, genetic epistasis with eRF1/eRF3/Pab1, helicase-mutant analysis, and in vivo termination assays in yeast\",\n      \"pmids\": [\"17272721\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mRNA export and termination functions are mechanistically coupled unknown\", \"Mammalian reconstitution lacking at this stage\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"A series of crystal structures of human DDX19B in multiple nucleotide/ligand states revealed mutually exclusive RNA and NUP214 binding, the N-terminal autoregulatory helix, and the Gle1-binding interface, providing an integrated structural framework for its catalytic cycle.\",\n      \"evidence\": \"X-ray crystallography of DDX19B–RNA–AMPPNP, DDX19B–NUP214, DDX19B open/closed states, and DDX19B C-terminal domain, all with biochemical and mutagenesis validation\",\n      \"pmids\": [\"19219046\", \"19244245\", \"19208808\", \"19805289\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full reconstituted NPC-like complex structure lacking\", \"How N-terminal helix regulation integrates with Gle1 activation kinetically unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Reconstitution of the nucleotide cycle showed that Nup159 promotes ADP release (later refined to Gle1 dissociation) while Gle1–IP6 primes ATP binding, defining the ordered cofactor logic at the NPC; FRAP revealed sub-second dynamic NPC association of DDX19B.\",\n      \"evidence\": \"In vitro nucleotide-binding/release assays, Dbp5-Nup159 bypass mutants, FRAP in yeast and human cells\",\n      \"pmids\": [\"21576266\", \"21576265\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact role of Nup159 (nucleotide exchange vs. Gle1 release) debated\", \"Single-molecule kinetics at NPCs lacking\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Detailed pre-steady-state kinetics quantified the DDX19B ATPase cycle — weak ATP binding (~4 mM Kd), 10-fold tighter ADP binding, and rate-limiting Pi release accelerated ~20-fold by RNA — establishing the biophysical basis for cofactor regulation.\",\n      \"evidence\": \"Stopped-flow kinetics and equilibrium binding assays\",\n      \"pmids\": [\"26730886\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Gle1's kinetic mechanism not yet quantified at this stage\", \"Physiological nucleotide concentrations not modeled\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identification of DDX19B's role in MKL1 nuclear import — requiring RNA binding but not helicase or NPC-binding activities — established the first export-independent nuclear import function for this helicase.\",\n      \"evidence\": \"siRNA knockdown, domain-mutant rescue, Co-IP, and nuclear import assays in mammalian cells\",\n      \"pmids\": [\"25585691\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which RNA binding alters MKL1 conformation unresolved\", \"Not independently replicated\", \"Whether this function is conserved in yeast unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing that DDX19B is required for pre-ribosomal subunit export but in an ATPase-independent manner distinguished this function mechanistically from mRNA export, suggesting a scaffolding or capture role at the NPC.\",\n      \"evidence\": \"Yeast temperature-sensitive mutants, ATPase-deficient alleles, Co-IP with Nmd3, fluorescence microscopy\",\n      \"pmids\": [\"26872259\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether DDX19B directly contacts pre-ribosomal particles or acts indirectly unknown\", \"Human validation lacking\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Reconstitution with mammalian DDX19 confirmed its role in translation termination — increasing termination complex formation and peptide release — extending the yeast findings and showing nucleotide-dependent association with pre-termination complexes.\",\n      \"evidence\": \"Reconstituted mammalian in vitro translation system with sucrose gradient sedimentation\",\n      \"pmids\": [\"28180304\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for DDX19–ribosome interaction unknown\", \"Whether mRNA export and termination pools of DDX19B are distinct in vivo unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Discovery that DDX19B relocalizes from NPCs to the nucleus under replication stress via ATR/Chk1 phosphorylation to resolve R-loops established a DNA damage response function: Chk1-phosphorylation disrupts NUP214 binding, and nuclear DDX19B's helicase activity unwinds DNA:RNA hybrids.\",\n      \"evidence\": \"Live-cell imaging, R-loop immunofluorescence, in vitro helicase assay, phosphorylation mutants, DNA fiber assays\",\n      \"pmids\": [\"28314779\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific Chk1 phosphorylation site(s) not fully mapped\", \"Whether R-loop resolution is a direct helicase activity on DNA:RNA hybrids in vivo confirmed only indirectly\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Establishing that Nup42 is required for Gle1-mediated DDX19B activation — forming a Nup42–Gle1–Dbp5 trimeric complex with InsP6 — completed the NPC-resident activating module architecture.\",\n      \"evidence\": \"In vitro ATPase reconstitution with yeast and human proteins, Co-IP, mRNA export assays\",\n      \"pmids\": [\"28869701\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural model of complete trimeric activating complex lacking\", \"Stoichiometry at NPCs unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Revised kinetic analysis showed Nup159 does not accelerate ADP release but instead weakens the Gle1–ADP–Dbp5 ternary complex ~18-fold, redefining Nup159's role as facilitating Gle1 recycling rather than acting as a nucleotide exchange factor.\",\n      \"evidence\": \"Stopped-flow kinetics and fluorescence equilibrium binding assays\",\n      \"pmids\": [\"29782832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Nup159 also modulates other steps in the full NPC context unknown\", \"Reconciliation with the 2011 model not fully settled\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Discovery that DDX19B negatively regulates type I interferon production — by recruiting Lamtor2 to disrupt TBK1/IKKε–IRF3 interactions and promote kinase degradation — revealed an innate immune signaling function validated by knockout mice with augmented IFN production.\",\n      \"evidence\": \"Reciprocal Co-IP, TALEN-generated knockout mice, virus infection assays\",\n      \"pmids\": [\"30699353\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether this immune function requires ATPase or RNA-binding activities unknown\", \"Mechanism of Lamtor2 recruitment unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of an N-terminal Xpo1-dependent NES in Dbp5 and separation-of-function alleles showing that nuclear shuttling is dispensable for mRNA export but specifically required for tRNA export established tRNA export as a distinct DDX19B function.\",\n      \"evidence\": \"Systematic alanine scanning mutagenesis (456 viable mutants), tRNA export assays in yeast\",\n      \"pmids\": [\"31453808\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of DDX19B action on tRNA substrates unknown at this point\", \"Human tRNA export role not tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that DDX19B tethers CTIF at the perinuclear region in a translationally incompetent state and hands it to CBP80 upon mRNA export established DDX19B as a spatial organizer of CBC-dependent translation and nonsense-mediated decay.\",\n      \"evidence\": \"Co-IP, fluorescence microscopy, siRNA knockdown, dominant-negative mutants, NMD reporter assays\",\n      \"pmids\": [\"34232997\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis for DDX19B–CTIF interaction unknown\", \"Whether this mechanism operates on all or a subset of mRNAs unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Quantitative kinetic dissection showed Gle1 activates DDX19B by two mechanisms — thermodynamic coupling that stabilizes the ATP-bound state (>100-fold preferential binding) and acceleration of rate-limiting Pi release (~20-fold) — providing the definitive kinetic model for the activating complex.\",\n      \"evidence\": \"Kinetic and equilibrium fluorescence assays, in vitro ATPase reconstitution\",\n      \"pmids\": [\"35286399\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How InsP6 and Nup42 quantitatively modulate these two mechanisms not fully integrated\", \"In vivo validation of kinetic parameters lacking\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identification of SUMOylation at K26 as a modification that enhances DDX19B–Gle1 interaction and is required for full mRNA export rescue added a post-translational regulatory layer to the ATPase cycle.\",\n      \"evidence\": \"In vivo SUMOylation assay, Co-IP, siRNA rescue with K26R mutant\",\n      \"pmids\": [\"35080244\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"SUMOylation dynamics and triggering signals unknown\", \"Whether K26 SUMOylation affects other DDX19B functions (termination, R-loop resolution) untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Direct demonstration that Dbp5 binds tRNA and functions in tRNA export parallel to Los1 — with tRNA synergizing with Gle1 to fully activate Dbp5 ATPase — defined the molecular mechanism for the tRNA export role first genetically identified in 2019.\",\n      \"evidence\": \"Co-IP, in vitro ATPase assays with tRNA, dominant-negative overexpression, genetic epistasis in yeast\",\n      \"pmids\": [\"38189406\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether DDX19B remodels tRNP complexes analogously to mRNP remodeling unknown\", \"Human tRNA export function not yet demonstrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis for the complete NPC-resident DDX19B activation complex in situ, how the multiple functions (mRNA export, tRNA export, translation termination, R-loop resolution, immune signaling) are partitioned among cellular pools, and whether substrate-specific cofactor interactions determine functional selectivity.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No cryo-EM or cryo-ET structure of DDX19B at the intact NPC\", \"Partitioning of DDX19B pools among its many functions not quantified\", \"Regulation by SUMOylation and Chk1 phosphorylation not integrated into a unified model\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 2, 3, 14, 26]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [6, 7, 15, 27]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [21]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [0, 1, 8, 12, 23]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [17]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 2, 4, 11, 19, 25]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [5, 17]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [16, 22, 27]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [21]}\n    ],\n    \"complexes\": [\n      \"Gle1–Nup42–InsP6 activation complex\",\n      \"NUP214–DDX19B NPC docking complex\"\n    ],\n    \"partners\": [\n      \"NUP214\",\n      \"GLE1\",\n      \"NUP42\",\n      \"RBM15\",\n      \"CTIF\",\n      \"eRF1\",\n      \"SLIP1\",\n      \"LAMTOR2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}