{"gene":"DRG1","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2007,"finding":"The AAA-ATPase Drg1 is essential for 60S ribosomal subunit maturation in yeast; functional inactivation of Drg1 causes cytoplasmic accumulation of shuttling pre-60S maturation factors (Rlp24, Arx1, Tif6, Nog1), and dominant-negative mutation in the D2 ATPase domain recapitulates this phenotype, demonstrating that ATPase activity is required for release of shuttling proteins from pre-60S particles shortly after nuclear export.","method":"Genetic inactivation, dominant-negative D2 ATPase domain mutant, subcellular fractionation, fluorescence microscopy in S. cerevisiae","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (genetics, dominant-negative mutagenesis, localization), replicated concept across subsequent studies","pmids":["17646390"],"is_preprint":false},{"year":2012,"finding":"The shuttling protein Rlp24 recruits Drg1 to pre-60S particles and stimulates its ATPase activity; ATP hydrolysis in the second AAA domain (D2) of Drg1 is required to release shuttling proteins. In vitro, Drg1 specifically and exclusively extracts Rlp24 from purified pre-60S particles in an ATP-dependent manner promoted by nucleoporin Nup116 interaction. Subsequent ATP hydrolysis in the first AAA domain (D1) dissociates Drg1 from Rlp24, enabling consecutive activity cycles.","method":"In vitro reconstitution with purified pre-60S particles, ATPase assays, domain mutagenesis, biochemical fractionation","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified components, ATPase domain mutagenesis, and mechanistic dissection in a single rigorous study","pmids":["23185031"],"is_preprint":false},{"year":2013,"finding":"Diazaborine inhibits ribosome biogenesis by targeting the AAA-ATPase Drg1; the drug binds into the second AAA domain (D2) of Drg1 in an ATP-dependent manner, inhibiting ATP hydrolysis at D2, thereby blocking Rlp24 release from pre-60S particles and preventing cytoplasmic preribosome maturation.","method":"Drug-target identification, biochemical inhibition assays, ATPase domain mutagenesis in yeast","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical target identification with mechanistic mutagenesis, consistent with prior structural and functional data","pmids":["24371142"],"is_preprint":false},{"year":2022,"finding":"Cryo-EM structures of yeast Drg1 in different nucleotide-binding states and benzo-diazaborine-treated states reveal that Drg1 hexamers transition between planar and helical conformations; benzo-diazaborine forms covalent adducts with ATP in both ATPase domains, locking the hexamer in a symmetric non-productive conformation that inhibits inter-protomer and inter-ring communication. A substrate-engaged mutant structure shows conserved pore-loops forming a spiral staircase interacting with polypeptide in a sequence-independent manner, suggesting Drg1 functions as an unfoldase that threads a substrate protein within the pre-60S particle.","method":"Cryo-EM structure determination, structure-based mutagenesis, biochemical inhibition assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structures in multiple states combined with structure-based mutagenesis and biochemical validation","pmids":["36351914"],"is_preprint":false},{"year":2005,"finding":"DFRP1 (DRG family regulatory protein 1) specifically binds DRG1 and stabilizes it by blocking poly-ubiquitination that would otherwise lead to proteolysis; the DRG1–DFRP1 interaction occurs in the cytoplasm. Knockout of dfrp1 reduces endogenous DRG1 expression, confirming DFRP1 is a specific in vivo regulator of DRG1 stability.","method":"Co-immunoprecipitation, transient transfection, dfrp1 knockout cell lines, immunofluorescence","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding demonstrated, genetic knockout confirms in vivo relevance, multiple orthogonal methods","pmids":["15676025"],"is_preprint":false},{"year":2009,"finding":"The DRG1/DFRP1 complex co-sediments with polysomes in mammalian cells, whereas the DRG2/DFRP2 complex does not associate with ribosomal fractions, indicating that DRG1/DFRP1 specifically modulates protein synthesis mechanisms distinct from DRG2/DFRP2.","method":"Polysome fractionation, co-sedimentation analysis, biochemical characterization in mammalian cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — polysome fractionation is a direct biochemical method; single lab, but clearly distinct result between DRG1 and DRG2 complexes","pmids":["19819225"],"is_preprint":false},{"year":2013,"finding":"Human DRG1 is a potassium-dependent GTPase; potassium strongly stimulates GTPase activity without changing DRG1 monomeric status. The DFRP domain of Lerepo4 (DFRP1) is solely responsible for a 4-fold stimulation of DRG1 catalytic activity and increased thermal stability, without affecting nucleotide affinity, possibly by favoring switch I reorientation via the TGS domain.","method":"Purified recombinant protein GTPase assays, domain deletion/point mutants, biochemical characterization","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assays with purified components and domain mutagenesis; single lab but multiple biochemical approaches","pmids":["23711155"],"is_preprint":false},{"year":2004,"finding":"DRG1/Rit42 is a microtubule-associated protein that localizes to centrosomes and participates in the spindle checkpoint in a p53-dependent manner; ectopic expression inhibits polyploidy in p53-deficient tumor cells and increases mitotic arrest upon spindle inhibitor treatment. siRNA knockdown of endogenous Rit42 in normal mammary epithelial cells causes loss of astral microtubules, failure of spindle fiber formation, and microtubule inhibitor-induced reduplication leading to polyploidy.","method":"Immunofluorescence localization, siRNA knockdown, ectopic overexpression, flow cytometry, spindle inhibitor treatment","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment linked to functional consequence, multiple cell-based assays; single lab","pmids":["15247272"],"is_preprint":false},{"year":2017,"finding":"Human DRG1 is a microtubule-binding protein that can diffuse on microtubules, promote their polymerization, drive microtubule bundling, and stabilize microtubules in vitro. In HeLa cells, reduced DRG1 levels delay progression from prophase to anaphase due to slowed spindle formation. GTP hydrolysis by DRG1 is not required for these microtubule-associated functions, but all protein domains are required for activities beyond microtubule binding.","method":"In vitro microtubule polymerization assays, TIRF microscopy, siRNA knockdown in HeLa cells, live-cell imaging, domain truncation analysis","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of microtubule activities plus cell-based functional validation with multiple orthogonal methods; single lab","pmids":["28855639"],"is_preprint":false},{"year":2017,"finding":"The N-terminal domain of Drg1 regulates ATPase activity through inter-domain communication with the adjacent D1 AAA domain; mutations at the N-domain/D1 interface dysregulate ATPase activity and alter interaction with the substrate Rlp24, resembling pathological mutations in the related AAA-ATPase p97 that cause IBMPFD.","method":"Mutagenesis of N-domain/D1 interface, ATPase activity assays, binding assays with Rlp24 in yeast","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — enzymatic assays with mutagenesis but single lab and limited structural validation in this study alone","pmids":["28303975"],"is_preprint":false},{"year":2004,"finding":"PTEN up-regulates DRG1 expression through an Akt-dependent pathway at the transcriptional level; overexpression of PTEN augments endogenous DRG1 protein, while siRNA knockdown of PTEN decreases DRG1, and a phospho-Akt inhibitor restores DRG1 expression in prostate and breast cancer cells.","method":"PTEN overexpression and siRNA knockdown, Akt inhibitor treatment, protein expression analysis, promoter/transcription level assessment","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA and overexpression with pharmacological inhibitor used orthogonally; single lab","pmids":["15520163"],"is_preprint":false},{"year":2006,"finding":"DRG-1 suppresses the expression of ATF3 (activating transcription factor 3) at the transcriptional level in prostate cancer cells; DRG-1 induction suppresses ATF3 mRNA/protein, DRG-1 siRNA up-regulates ATF3, and DRG-1 suppresses ATF3 promoter activity. ATF3 overexpression promotes invasiveness and enhances spontaneous lung metastasis in SCID mice, identifying ATF3 downregulation as a downstream mechanism of DRG-1 metastasis suppression.","method":"Microarray analysis, siRNA knockdown, ATF3 promoter luciferase assay, overexpression, in vivo SCID mouse metastasis model","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter assay plus siRNA and in vivo validation; single lab but multiple orthogonal approaches","pmids":["17178897"],"is_preprint":false},{"year":2006,"finding":"DRG-1 interacts with human NADE (p75NTR-associated cell death executor) in vivo and in vitro; the interaction occurs in the cytoplasm and requires the N-terminal of DRG-1 and the C-terminal of NADE. Stable DRG-1 expression promotes cell proliferation (increased S phase population) in 293 and PC12 cells, and this promotion is suppressed by NADE overexpression.","method":"Co-immunoprecipitation, in vitro binding, immunofluorescence co-localization, domain mapping, flow cytometry cell cycle analysis","journal":"Brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — reciprocal binding and domain mapping established, functional consequence shown by cell cycle analysis; single lab, limited mechanistic depth","pmids":["16777077"],"is_preprint":false},{"year":2021,"finding":"DRG1 maintains intestinal epithelial cell junctions and barrier function by regulating RAC1 activity; DRG1 deficiency destabilizes E-cadherin and occludin at the cell membrane and increases epithelial monolayer permeability, while DRG1 overexpression prevents LPS-induced disruption. RAC1 inhibition with NSC23766 attenuates intestinal injury consistent with DRG1 acting upstream of RAC1.","method":"Immunoprecipitation/mass spectrometry interactome, stable DRG1 silencing/overexpression in Caco2 and FHs74Int cells, permeability assays, RAC1 inhibitor treatment, in vivo NEC model","journal":"Digestive diseases and sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — interactome identification combined with functional cell-based assays and in vivo validation; single lab","pmids":["33471252"],"is_preprint":false},{"year":2023,"finding":"Loss-of-function DRG1 germline variants (stop-gained and missense) cause a recessive neurodevelopmental disorder; patient-derived fibroblasts show severely disrupted DRG1 mRNA/protein stability, impaired GTPase activity of the mutant protein, and compromised binding to partner protein ZC3H15 (DFRP1 ortholog). Targeted inactivation of mouse Drg1 results in preweaning lethality, establishing that DRG1 is essential for mammalian development.","method":"Patient-derived fibroblast analysis, in vitro GTPase activity assays on mutant proteins, co-immunoprecipitation binding assay, mouse Drg1 knockout","journal":"Genetics in medicine","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assay with loss-of-function variants, partner binding assay, and mouse genetic knockout; multiple orthogonal methods in single study","pmids":["37179472"],"is_preprint":false},{"year":2020,"finding":"METTL3-mediated m6A modification of DRG1 mRNA promotes its stability via ELAVL1 (HuR) binding; knockdown of METTL3 decreases m6A levels and DRG1 mRNA, while ELAVL1 knockdown impairs DRG1 mRNA stability, reducing both mRNA and protein levels in osteosarcoma cells.","method":"m6A measurement, siRNA knockdown of METTL3 and ELAVL1, mRNA stability assays, qPCR and western blot in osteosarcoma cells","journal":"Bioscience reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct m6A and mRNA stability measurements with genetic perturbations; single lab, two orthogonal RNA-level methods","pmids":["32266933"],"is_preprint":false},{"year":2025,"finding":"NO2/NaNO3 promotes the interaction between DRG1 and CDK5 during cellular senescence, as demonstrated by co-immunoprecipitation. ROS-dependent upregulation of DRG1 and CDK5 mediates NO2-induced bronchial epithelial senescence, and si-DRG1 treatment alleviates senescence phenotypes including G1 arrest and senescence marker expression.","method":"Co-immunoprecipitation, siRNA knockdown, ROS inhibitor (NAC) treatment, β-galactosidase activity assay, cell cycle analysis","journal":"Journal of environmental sciences (China)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP for DRG1-CDK5 interaction, single lab, indirect mechanistic pathway placement","pmids":["42070819"],"is_preprint":false},{"year":2022,"finding":"Both recombinant sponge and human DRG1 are predominantly monomers that form complexes with DFRP1 and bind non-specifically to RNA and DNA; DRG1 influences α-tubulin dynamics and its intracellular localization is cytosolic, conserved between sponge and human.","method":"Recombinant protein purification, biochemical binding assays, immunofluorescence localization, α-tubulin dynamics assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical and cell-based characterization with multiple methods; evolutionary comparison supports functional conservation","pmids":["35790840"],"is_preprint":false},{"year":2025,"finding":"SPATA5 (a metazoan-specific AAA-ATPase) evolved from the yeast Drg1 ortholog and operates within the eumetazoan-specific SPATA5-SPATA5L1-CINP-C1ORF109 (55LCC) complex for cytoplasmic pre-60S maturation in human cells; acute depletion of each component impairs pre-60S maturation, and SPATA5 ATPase activity is functionally more important than SPATA5L1's.","method":"Protein-protein interaction screen, cryo-EM, X-ray crystallography, acute depletion, ATPase mutant swap-in","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — structural and functional data on the complex, but preprint; DRG1 itself is referenced as the evolutionary ancestor rather than directly studied","pmids":["bio_10.1101_2025.11.07.687187"],"is_preprint":true}],"current_model":"DRG1 (also known as NEDD3) is a conserved GTPase/ATPase with two distinct mechanistic roles: in yeast and likely metazoans, the AAA-ATPase activity of Drg1 drives cytoplasmic pre-60S ribosome maturation by releasing the adaptor protein Rlp24 from pre-60S particles (stimulated by Rlp24 itself and nucleoporin Nup116), acting as an unfoldase that threads substrate polypeptides through its central pore; in mammalian cells, DRG1 is a microtubule-associated GTPase that promotes microtubule polymerization and bundling, localizes to centrosomes, participates in spindle assembly checkpoint in a p53-dependent manner, is stabilized by its binding partner DFRP1 (which also stimulates its GTPase activity 4-fold), associates with polysomes, suppresses tumor metastasis partly by transcriptionally downregulating ATF3, maintains epithelial barrier integrity via RAC1 regulation, and loss-of-function variants cause a recessive neurodevelopmental syndrome with impaired GTPase activity and disrupted ZC3H15/DFRP1 binding."},"narrative":{"mechanistic_narrative":"DRG1 is a conserved nucleotide-binding protein that has been characterized in two principal mechanistic contexts: AAA-ATPase-driven ribosome maturation in yeast and GTPase/microtubule-associated functions in mammalian cells [PMID:17646390, PMID:28855639]. In yeast, the AAA-ATPase Drg1 is essential for cytoplasmic maturation of the pre-60S ribosomal subunit, where it releases the shuttling adaptor Rlp24 from exported pre-60S particles; Rlp24 itself recruits Drg1 and stimulates its ATPase activity, hydrolysis in the D2 domain drives substrate release, and subsequent D1 hydrolysis dissociates Drg1 to reset the cycle, with nucleoporin Nup116 promoting the reaction [PMID:17646390, PMID:23185031]. Cryo-EM structures show Drg1 hexamers cycling between planar and helical states with pore-loops forming a spiral staircase that engages polypeptide sequence-independently, defining Drg1 as an unfoldase that threads substrate through its central pore; the inhibitor diazaborine forms covalent ATP adducts in the ATPase domains to lock a non-productive conformation [PMID:24371142, PMID:36351914]. In mammalian cells DRG1 is a potassium-dependent GTPase whose stability and catalytic activity are governed by its binding partner DFRP1, which blocks DRG1 poly-ubiquitination and proteolysis and stimulates GTPase activity ~4-fold [PMID:15676025, PMID:23711155]. DRG1 also acts as a microtubule-associated protein that diffuses on microtubules, promotes their polymerization, bundling and stabilization, localizes to centrosomes, and supports spindle formation and the p53-dependent spindle checkpoint independently of GTP hydrolysis [PMID:15247272, PMID:28855639]. At the cellular level, DRG1 functions as a metastasis suppressor by transcriptionally downregulating ATF3, maintains epithelial junction integrity through RAC1 regulation, and its mRNA stability is controlled by METTL3/ELAVL1-dependent m6A modification [PMID:17178897, PMID:33471252, PMID:32266933]. Biallelic loss-of-function DRG1 variants that impair GTPase activity and disrupt binding to the DFRP1 ortholog ZC3H15 cause a recessive neurodevelopmental disorder, and Drg1 knockout is lethal in mice, establishing the protein as essential for mammalian development [PMID:37179472].","teleology":[{"year":2007,"claim":"Established that Drg1 ATPase activity is essential for a defined step of ribosome biogenesis, answering what cellular process this AAA-ATPase serves.","evidence":"Genetic inactivation and dominant-negative D2 domain mutant with subcellular fractionation in S. cerevisiae","pmids":["17646390"],"confidence":"High","gaps":["Did not identify the direct substrate released","Mechanism of substrate engagement unknown"]},{"year":2012,"claim":"Resolved how Drg1 acts on pre-60S particles by identifying Rlp24 as the specific extracted substrate and dissecting the ordered D2-then-D1 hydrolysis cycle, answering the directionality and recruitment logic.","evidence":"In vitro reconstitution with purified pre-60S particles, ATPase assays, and domain mutagenesis","pmids":["23185031"],"confidence":"High","gaps":["Structural basis of substrate threading not yet resolved","Role of Nup116 interaction not structurally defined"]},{"year":2013,"claim":"Identified diazaborine's mechanism of action as ATP-dependent binding into the D2 domain, validating Drg1 as a druggable target and confirming D2 hydrolysis as the critical step.","evidence":"Drug-target identification, biochemical inhibition assays, and ATPase domain mutagenesis in yeast","pmids":["24371142"],"confidence":"High","gaps":["Structural detail of the inhibited state addressed only later","Selectivity over other AAA-ATPases not fully defined"]},{"year":2017,"claim":"Showed the N-domain regulates ATPase activity via inter-domain communication with D1, answering how Drg1's catalytic cycle is internally coordinated.","evidence":"Mutagenesis of N-domain/D1 interface with ATPase and Rlp24-binding assays in yeast","pmids":["28303975"],"confidence":"Medium","gaps":["Limited structural validation in this study","Physiological consequences of dysregulation not tested in vivo"]},{"year":2022,"claim":"Provided the structural mechanism: cryo-EM revealed planar-to-helical hexamer transitions and a substrate-engaged spiral pore-loop staircase, establishing Drg1 as a polypeptide-threading unfoldase and explaining diazaborine inhibition.","evidence":"Cryo-EM in multiple nucleotide and inhibitor states with structure-based mutagenesis","pmids":["36351914"],"confidence":"High","gaps":["Identity of the threaded substrate region within pre-60S not defined","Coupling to downstream maturation factors unresolved"]},{"year":2025,"claim":"Connected the yeast Drg1 paradigm to humans by showing the metazoan AAA-ATPase SPATA5 evolved from Drg1 and performs cytoplasmic pre-60S maturation within the 55LCC complex.","evidence":"Interaction screen, cryo-EM, crystallography, and acute depletion with ATPase mutant swap-in (preprint)","pmids":["bio_10.1101_2025.11.07.687187"],"confidence":"Medium","gaps":["DRG1 itself studied as evolutionary ancestor rather than directly","Preprint, not peer-reviewed","Whether human DRG1 retains any pre-60S role unaddressed"]},{"year":2005,"claim":"Identified DFRP1 as the specific stabilizing partner of mammalian DRG1, answering how DRG1 protein levels are controlled.","evidence":"Co-immunoprecipitation, dfrp1 knockout cell lines, and immunofluorescence","pmids":["15676025"],"confidence":"High","gaps":["Identity of the ubiquitin ligase acting on DRG1 unknown","Functional output of stabilization not yet defined"]},{"year":2009,"claim":"Showed the DRG1/DFRP1 complex co-sediments with polysomes whereas DRG2/DFRP2 does not, distinguishing DRG1 as the translation-associated paralog.","evidence":"Polysome fractionation and co-sedimentation in mammalian cells","pmids":["19819225"],"confidence":"Medium","gaps":["Direct role in translation not functionally demonstrated","Single lab"]},{"year":2013,"claim":"Defined DRG1 as a potassium-dependent GTPase and pinpointed the DFRP domain as the 4-fold catalytic stimulator, establishing the enzymatic regulation of the mammalian protein.","evidence":"Purified recombinant GTPase assays with domain deletion and point mutants","pmids":["23711155"],"confidence":"High","gaps":["Physiological GTPase substrate/effector unknown","Cellular consequence of GTP hydrolysis not addressed here"]},{"year":2004,"claim":"First linked DRG1 to mitotic fidelity, showing it is a centrosome- and microtubule-associated protein required for spindle integrity in a p53-dependent checkpoint.","evidence":"Immunofluorescence, siRNA knockdown, ectopic overexpression, and flow cytometry with spindle inhibitors","pmids":["15247272"],"confidence":"Medium","gaps":["Molecular basis of p53 dependence unresolved","Single lab"]},{"year":2017,"claim":"Reconstituted DRG1's direct microtubule activities, showing it diffuses on, polymerizes, bundles and stabilizes microtubules independently of GTP hydrolysis, separating this function from its GTPase cycle.","evidence":"In vitro polymerization and TIRF assays, siRNA in HeLa, live imaging, and domain truncations","pmids":["28855639"],"confidence":"High","gaps":["How non-catalytic microtubule activity integrates with GTPase function unclear","Single lab"]},{"year":2004,"claim":"Placed DRG1 downstream of PTEN/Akt signaling, showing PTEN transcriptionally upregulates DRG1, linking it to a tumor-suppressor pathway.","evidence":"PTEN overexpression/knockdown and Akt inhibitor treatment in prostate and breast cancer cells","pmids":["15520163"],"confidence":"Medium","gaps":["Transcription factor mediating PTEN-dependent induction unidentified","Single lab"]},{"year":2006,"claim":"Identified ATF3 as a downstream effector, establishing transcriptional ATF3 repression as a mechanism of DRG1 metastasis suppression.","evidence":"Microarray, siRNA, ATF3 promoter luciferase assay, and in vivo SCID metastasis model","pmids":["17178897"],"confidence":"Medium","gaps":["Mechanism by which DRG1 represses the ATF3 promoter unknown","Single lab"]},{"year":2006,"claim":"Identified a cytoplasmic DRG1–NADE interaction and a proliferation-promoting role antagonized by NADE, expanding DRG1's interactome.","evidence":"Co-IP, in vitro binding, domain mapping, and cell-cycle flow cytometry","pmids":["16777077"],"confidence":"Medium","gaps":["Mechanistic link between binding and proliferation unresolved","Single lab, limited depth"]},{"year":2020,"claim":"Established post-transcriptional control of DRG1, showing METTL3-deposited m6A and ELAVL1 binding stabilize DRG1 mRNA.","evidence":"m6A measurement, METTL3/ELAVL1 knockdown, and mRNA stability assays in osteosarcoma cells","pmids":["32266933"],"confidence":"Medium","gaps":["Functional output of DRG1 in osteosarcoma not mechanistically tied to m6A","Single lab"]},{"year":2021,"claim":"Defined a DRG1 role in epithelial barrier maintenance through RAC1 regulation, broadening its physiological function.","evidence":"Interactome MS, DRG1 silencing/overexpression, permeability assays, RAC1 inhibitor, and in vivo NEC model","pmids":["33471252"],"confidence":"Medium","gaps":["Direct biochemical link between DRG1 and RAC1 activation not established","Single lab"]},{"year":2022,"claim":"Demonstrated evolutionary conservation of DRG1's monomeric state, DFRP1 complex formation, nucleic acid binding, and tubulin influence from sponge to human.","evidence":"Recombinant protein purification, binding assays, immunofluorescence, and α-tubulin dynamics assay","pmids":["35790840"],"confidence":"Medium","gaps":["Biological significance of nonspecific nucleic acid binding unclear","Single lab"]},{"year":2023,"claim":"Established DRG1 as a Mendelian disease gene, showing biallelic loss-of-function variants impair GTPase activity and ZC3H15/DFRP1 binding and cause a recessive neurodevelopmental disorder, with mouse knockout lethal.","evidence":"Patient fibroblast analysis, GTPase assays on mutants, Co-IP binding, and mouse Drg1 knockout","pmids":["37179472"],"confidence":"High","gaps":["Cellular pathway whose disruption causes neurodevelopmental phenotype unresolved","Tissue-specific requirements not defined"]},{"year":2025,"claim":"Linked DRG1 to cellular senescence via a NO2/ROS-induced interaction with CDK5 in bronchial epithelium.","evidence":"Co-IP, siRNA, NAC treatment, β-galactosidase and cell-cycle assays","pmids":["42070819"],"confidence":"Low","gaps":["Single Co-IP for DRG1-CDK5 without reciprocal validation","Indirect mechanistic placement","Direct functional consequence of the interaction undefined"]},{"year":null,"claim":"Whether mammalian DRG1 retains a direct role in cytoplasmic pre-60S ribosome maturation analogous to its yeast ortholog, and how its GTPase, microtubule, and ribosome-associated activities are integrated, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No human GTPase effector/substrate identified","Relationship between DRG1 and the metazoan SPATA5/55LCC pre-60S machinery undefined","Mechanism connecting molecular activities to the neurodevelopmental phenotype unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[6,14]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[7,8]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[11]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4,17]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[7]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[7,8]},{"term_id":"GO:0005840","term_label":"ribosome","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,1,5]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[7,8]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[14]}],"complexes":["DRG1–DFRP1 complex"],"partners":["DFRP1","ZC3H15","RLP24","NUP116","RAC1","NADE","CDK5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q92597","full_name":"Protein NDRG1","aliases":["Differentiation-related gene 1 protein","DRG-1","N-myc downstream-regulated gene 1 protein","Nickel-specific induction protein Cap43","Reducing agents and tunicamycin-responsive protein","RTP","Rit42"],"length_aa":394,"mass_kda":42.8,"function":"Stress-responsive protein involved in hormone responses, cell growth, and differentiation. Acts as a tumor suppressor in many cell types. Necessary but not sufficient for p53/TP53-mediated caspase activation and apoptosis. Has a role in cell trafficking, notably of the Schwann cell, and is necessary for the maintenance and development of the peripheral nerve myelin sheath. Required for vesicular recycling of CDH1 and TF. May also function in lipid trafficking. Protects cells from spindle disruption damage. Functions in p53/TP53-dependent mitotic spindle checkpoint. Regulates microtubule dynamics and maintains euploidy","subcellular_location":"Cytoplasm, cytosol; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Nucleus; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q92597/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DRG1","classification":"Not Classified","n_dependent_lines":243,"n_total_lines":1208,"dependency_fraction":0.201158940397351},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000185721","cell_line_id":"CID001617","localizations":[{"compartment":"cytoplasmic","grade":3}],"interactors":[{"gene":"RPS20","stoichiometry":10.0},{"gene":"RPS13","stoichiometry":10.0},{"gene":"RPL7A","stoichiometry":10.0},{"gene":"RPL27","stoichiometry":10.0},{"gene":"ZC3H15","stoichiometry":10.0},{"gene":"RPS10;RPS10-NUDT3","stoichiometry":10.0},{"gene":"RPL6","stoichiometry":10.0},{"gene":"RPL27A","stoichiometry":10.0},{"gene":"RPL13","stoichiometry":10.0},{"gene":"RPS2","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/target/CID001617","total_profiled":1310},"omim":[{"mim_id":"621306","title":"JUMONJI DOMAIN-CONTAINING PROTEIN 7; JMJD7","url":"https://www.omim.org/entry/621306"},{"mim_id":"620641","title":"TAN-ALMURSHEDI SYNDROME; TANALS","url":"https://www.omim.org/entry/620641"},{"mim_id":"619704","title":"ZINC FINGER CCCH DOMAIN-CONTAINING PROTEIN 15; ZC3H15","url":"https://www.omim.org/entry/619704"},{"mim_id":"610902","title":"VESSICLE TRAFFICKING 1; VTA1","url":"https://www.omim.org/entry/610902"},{"mim_id":"605272","title":"NMYC DOWNSTREAM-REGULATED GENE 2; NDRG2","url":"https://www.omim.org/entry/605272"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nuclear bodies","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"testis","ntpm":149.8}],"url":"https://www.proteinatlas.org/search/DRG1"},"hgnc":{"alias_symbol":[],"prev_symbol":["NEDD3"]},"alphafold":{"accession":"Q92597","domains":[{"cath_id":"3.40.50.1820","chopping":"33-313","consensus_level":"high","plddt":92.4352,"start":33,"end":313}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92597","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q92597-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q92597-F1-predicted_aligned_error_v6.png","plddt_mean":78.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DRG1","jax_strain_url":"https://www.jax.org/strain/search?query=DRG1"},"sequence":{"accession":"Q92597","fasta_url":"https://rest.uniprot.org/uniprotkb/Q92597.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q92597/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92597"}},"corpus_meta":[{"pmid":"10676663","id":"PMC_10676663","title":"Drg-1 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activity is required for release of shuttling proteins from pre-60S particles shortly after nuclear export.\",\n      \"method\": \"Genetic inactivation, dominant-negative D2 ATPase domain mutant, subcellular fractionation, fluorescence microscopy in S. cerevisiae\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (genetics, dominant-negative mutagenesis, localization), replicated concept across subsequent studies\",\n      \"pmids\": [\"17646390\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The shuttling protein Rlp24 recruits Drg1 to pre-60S particles and stimulates its ATPase activity; ATP hydrolysis in the second AAA domain (D2) of Drg1 is required to release shuttling proteins. In vitro, Drg1 specifically and exclusively extracts Rlp24 from purified pre-60S particles in an ATP-dependent manner promoted by nucleoporin Nup116 interaction. Subsequent ATP hydrolysis in the first AAA domain (D1) dissociates Drg1 from Rlp24, enabling consecutive activity cycles.\",\n      \"method\": \"In vitro reconstitution with purified pre-60S particles, ATPase assays, domain mutagenesis, biochemical fractionation\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified components, ATPase domain mutagenesis, and mechanistic dissection in a single rigorous study\",\n      \"pmids\": [\"23185031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Diazaborine inhibits ribosome biogenesis by targeting the AAA-ATPase Drg1; the drug binds into the second AAA domain (D2) of Drg1 in an ATP-dependent manner, inhibiting ATP hydrolysis at D2, thereby blocking Rlp24 release from pre-60S particles and preventing cytoplasmic preribosome maturation.\",\n      \"method\": \"Drug-target identification, biochemical inhibition assays, ATPase domain mutagenesis in yeast\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical target identification with mechanistic mutagenesis, consistent with prior structural and functional data\",\n      \"pmids\": [\"24371142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cryo-EM structures of yeast Drg1 in different nucleotide-binding states and benzo-diazaborine-treated states reveal that Drg1 hexamers transition between planar and helical conformations; benzo-diazaborine forms covalent adducts with ATP in both ATPase domains, locking the hexamer in a symmetric non-productive conformation that inhibits inter-protomer and inter-ring communication. A substrate-engaged mutant structure shows conserved pore-loops forming a spiral staircase interacting with polypeptide in a sequence-independent manner, suggesting Drg1 functions as an unfoldase that threads a substrate protein within the pre-60S particle.\",\n      \"method\": \"Cryo-EM structure determination, structure-based mutagenesis, biochemical inhibition assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structures in multiple states combined with structure-based mutagenesis and biochemical validation\",\n      \"pmids\": [\"36351914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"DFRP1 (DRG family regulatory protein 1) specifically binds DRG1 and stabilizes it by blocking poly-ubiquitination that would otherwise lead to proteolysis; the DRG1–DFRP1 interaction occurs in the cytoplasm. Knockout of dfrp1 reduces endogenous DRG1 expression, confirming DFRP1 is a specific in vivo regulator of DRG1 stability.\",\n      \"method\": \"Co-immunoprecipitation, transient transfection, dfrp1 knockout cell lines, immunofluorescence\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding demonstrated, genetic knockout confirms in vivo relevance, multiple orthogonal methods\",\n      \"pmids\": [\"15676025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The DRG1/DFRP1 complex co-sediments with polysomes in mammalian cells, whereas the DRG2/DFRP2 complex does not associate with ribosomal fractions, indicating that DRG1/DFRP1 specifically modulates protein synthesis mechanisms distinct from DRG2/DFRP2.\",\n      \"method\": \"Polysome fractionation, co-sedimentation analysis, biochemical characterization in mammalian cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — polysome fractionation is a direct biochemical method; single lab, but clearly distinct result between DRG1 and DRG2 complexes\",\n      \"pmids\": [\"19819225\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Human DRG1 is a potassium-dependent GTPase; potassium strongly stimulates GTPase activity without changing DRG1 monomeric status. The DFRP domain of Lerepo4 (DFRP1) is solely responsible for a 4-fold stimulation of DRG1 catalytic activity and increased thermal stability, without affecting nucleotide affinity, possibly by favoring switch I reorientation via the TGS domain.\",\n      \"method\": \"Purified recombinant protein GTPase assays, domain deletion/point mutants, biochemical characterization\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assays with purified components and domain mutagenesis; single lab but multiple biochemical approaches\",\n      \"pmids\": [\"23711155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"DRG1/Rit42 is a microtubule-associated protein that localizes to centrosomes and participates in the spindle checkpoint in a p53-dependent manner; ectopic expression inhibits polyploidy in p53-deficient tumor cells and increases mitotic arrest upon spindle inhibitor treatment. siRNA knockdown of endogenous Rit42 in normal mammary epithelial cells causes loss of astral microtubules, failure of spindle fiber formation, and microtubule inhibitor-induced reduplication leading to polyploidy.\",\n      \"method\": \"Immunofluorescence localization, siRNA knockdown, ectopic overexpression, flow cytometry, spindle inhibitor treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment linked to functional consequence, multiple cell-based assays; single lab\",\n      \"pmids\": [\"15247272\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Human DRG1 is a microtubule-binding protein that can diffuse on microtubules, promote their polymerization, drive microtubule bundling, and stabilize microtubules in vitro. In HeLa cells, reduced DRG1 levels delay progression from prophase to anaphase due to slowed spindle formation. GTP hydrolysis by DRG1 is not required for these microtubule-associated functions, but all protein domains are required for activities beyond microtubule binding.\",\n      \"method\": \"In vitro microtubule polymerization assays, TIRF microscopy, siRNA knockdown in HeLa cells, live-cell imaging, domain truncation analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of microtubule activities plus cell-based functional validation with multiple orthogonal methods; single lab\",\n      \"pmids\": [\"28855639\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The N-terminal domain of Drg1 regulates ATPase activity through inter-domain communication with the adjacent D1 AAA domain; mutations at the N-domain/D1 interface dysregulate ATPase activity and alter interaction with the substrate Rlp24, resembling pathological mutations in the related AAA-ATPase p97 that cause IBMPFD.\",\n      \"method\": \"Mutagenesis of N-domain/D1 interface, ATPase activity assays, binding assays with Rlp24 in yeast\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — enzymatic assays with mutagenesis but single lab and limited structural validation in this study alone\",\n      \"pmids\": [\"28303975\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PTEN up-regulates DRG1 expression through an Akt-dependent pathway at the transcriptional level; overexpression of PTEN augments endogenous DRG1 protein, while siRNA knockdown of PTEN decreases DRG1, and a phospho-Akt inhibitor restores DRG1 expression in prostate and breast cancer cells.\",\n      \"method\": \"PTEN overexpression and siRNA knockdown, Akt inhibitor treatment, protein expression analysis, promoter/transcription level assessment\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA and overexpression with pharmacological inhibitor used orthogonally; single lab\",\n      \"pmids\": [\"15520163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"DRG-1 suppresses the expression of ATF3 (activating transcription factor 3) at the transcriptional level in prostate cancer cells; DRG-1 induction suppresses ATF3 mRNA/protein, DRG-1 siRNA up-regulates ATF3, and DRG-1 suppresses ATF3 promoter activity. ATF3 overexpression promotes invasiveness and enhances spontaneous lung metastasis in SCID mice, identifying ATF3 downregulation as a downstream mechanism of DRG-1 metastasis suppression.\",\n      \"method\": \"Microarray analysis, siRNA knockdown, ATF3 promoter luciferase assay, overexpression, in vivo SCID mouse metastasis model\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter assay plus siRNA and in vivo validation; single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"17178897\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"DRG-1 interacts with human NADE (p75NTR-associated cell death executor) in vivo and in vitro; the interaction occurs in the cytoplasm and requires the N-terminal of DRG-1 and the C-terminal of NADE. Stable DRG-1 expression promotes cell proliferation (increased S phase population) in 293 and PC12 cells, and this promotion is suppressed by NADE overexpression.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding, immunofluorescence co-localization, domain mapping, flow cytometry cell cycle analysis\",\n      \"journal\": \"Brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — reciprocal binding and domain mapping established, functional consequence shown by cell cycle analysis; single lab, limited mechanistic depth\",\n      \"pmids\": [\"16777077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"DRG1 maintains intestinal epithelial cell junctions and barrier function by regulating RAC1 activity; DRG1 deficiency destabilizes E-cadherin and occludin at the cell membrane and increases epithelial monolayer permeability, while DRG1 overexpression prevents LPS-induced disruption. RAC1 inhibition with NSC23766 attenuates intestinal injury consistent with DRG1 acting upstream of RAC1.\",\n      \"method\": \"Immunoprecipitation/mass spectrometry interactome, stable DRG1 silencing/overexpression in Caco2 and FHs74Int cells, permeability assays, RAC1 inhibitor treatment, in vivo NEC model\",\n      \"journal\": \"Digestive diseases and sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — interactome identification combined with functional cell-based assays and in vivo validation; single lab\",\n      \"pmids\": [\"33471252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Loss-of-function DRG1 germline variants (stop-gained and missense) cause a recessive neurodevelopmental disorder; patient-derived fibroblasts show severely disrupted DRG1 mRNA/protein stability, impaired GTPase activity of the mutant protein, and compromised binding to partner protein ZC3H15 (DFRP1 ortholog). Targeted inactivation of mouse Drg1 results in preweaning lethality, establishing that DRG1 is essential for mammalian development.\",\n      \"method\": \"Patient-derived fibroblast analysis, in vitro GTPase activity assays on mutant proteins, co-immunoprecipitation binding assay, mouse Drg1 knockout\",\n      \"journal\": \"Genetics in medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assay with loss-of-function variants, partner binding assay, and mouse genetic knockout; multiple orthogonal methods in single study\",\n      \"pmids\": [\"37179472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"METTL3-mediated m6A modification of DRG1 mRNA promotes its stability via ELAVL1 (HuR) binding; knockdown of METTL3 decreases m6A levels and DRG1 mRNA, while ELAVL1 knockdown impairs DRG1 mRNA stability, reducing both mRNA and protein levels in osteosarcoma cells.\",\n      \"method\": \"m6A measurement, siRNA knockdown of METTL3 and ELAVL1, mRNA stability assays, qPCR and western blot in osteosarcoma cells\",\n      \"journal\": \"Bioscience reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct m6A and mRNA stability measurements with genetic perturbations; single lab, two orthogonal RNA-level methods\",\n      \"pmids\": [\"32266933\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NO2/NaNO3 promotes the interaction between DRG1 and CDK5 during cellular senescence, as demonstrated by co-immunoprecipitation. ROS-dependent upregulation of DRG1 and CDK5 mediates NO2-induced bronchial epithelial senescence, and si-DRG1 treatment alleviates senescence phenotypes including G1 arrest and senescence marker expression.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, ROS inhibitor (NAC) treatment, β-galactosidase activity assay, cell cycle analysis\",\n      \"journal\": \"Journal of environmental sciences (China)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP for DRG1-CDK5 interaction, single lab, indirect mechanistic pathway placement\",\n      \"pmids\": [\"42070819\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Both recombinant sponge and human DRG1 are predominantly monomers that form complexes with DFRP1 and bind non-specifically to RNA and DNA; DRG1 influences α-tubulin dynamics and its intracellular localization is cytosolic, conserved between sponge and human.\",\n      \"method\": \"Recombinant protein purification, biochemical binding assays, immunofluorescence localization, α-tubulin dynamics assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical and cell-based characterization with multiple methods; evolutionary comparison supports functional conservation\",\n      \"pmids\": [\"35790840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SPATA5 (a metazoan-specific AAA-ATPase) evolved from the yeast Drg1 ortholog and operates within the eumetazoan-specific SPATA5-SPATA5L1-CINP-C1ORF109 (55LCC) complex for cytoplasmic pre-60S maturation in human cells; acute depletion of each component impairs pre-60S maturation, and SPATA5 ATPase activity is functionally more important than SPATA5L1's.\",\n      \"method\": \"Protein-protein interaction screen, cryo-EM, X-ray crystallography, acute depletion, ATPase mutant swap-in\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — structural and functional data on the complex, but preprint; DRG1 itself is referenced as the evolutionary ancestor rather than directly studied\",\n      \"pmids\": [\"bio_10.1101_2025.11.07.687187\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"DRG1 (also known as NEDD3) is a conserved GTPase/ATPase with two distinct mechanistic roles: in yeast and likely metazoans, the AAA-ATPase activity of Drg1 drives cytoplasmic pre-60S ribosome maturation by releasing the adaptor protein Rlp24 from pre-60S particles (stimulated by Rlp24 itself and nucleoporin Nup116), acting as an unfoldase that threads substrate polypeptides through its central pore; in mammalian cells, DRG1 is a microtubule-associated GTPase that promotes microtubule polymerization and bundling, localizes to centrosomes, participates in spindle assembly checkpoint in a p53-dependent manner, is stabilized by its binding partner DFRP1 (which also stimulates its GTPase activity 4-fold), associates with polysomes, suppresses tumor metastasis partly by transcriptionally downregulating ATF3, maintains epithelial barrier integrity via RAC1 regulation, and loss-of-function variants cause a recessive neurodevelopmental syndrome with impaired GTPase activity and disrupted ZC3H15/DFRP1 binding.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DRG1 is a conserved nucleotide-binding protein that has been characterized in two principal mechanistic contexts: AAA-ATPase-driven ribosome maturation in yeast and GTPase/microtubule-associated functions in mammalian cells [#0, #8]. In yeast, the AAA-ATPase Drg1 is essential for cytoplasmic maturation of the pre-60S ribosomal subunit, where it releases the shuttling adaptor Rlp24 from exported pre-60S particles; Rlp24 itself recruits Drg1 and stimulates its ATPase activity, hydrolysis in the D2 domain drives substrate release, and subsequent D1 hydrolysis dissociates Drg1 to reset the cycle, with nucleoporin Nup116 promoting the reaction [#0, #1]. Cryo-EM structures show Drg1 hexamers cycling between planar and helical states with pore-loops forming a spiral staircase that engages polypeptide sequence-independently, defining Drg1 as an unfoldase that threads substrate through its central pore; the inhibitor diazaborine forms covalent ATP adducts in the ATPase domains to lock a non-productive conformation [#2, #3]. In mammalian cells DRG1 is a potassium-dependent GTPase whose stability and catalytic activity are governed by its binding partner DFRP1, which blocks DRG1 poly-ubiquitination and proteolysis and stimulates GTPase activity ~4-fold [#4, #6]. DRG1 also acts as a microtubule-associated protein that diffuses on microtubules, promotes their polymerization, bundling and stabilization, localizes to centrosomes, and supports spindle formation and the p53-dependent spindle checkpoint independently of GTP hydrolysis [#7, #8]. At the cellular level, DRG1 functions as a metastasis suppressor by transcriptionally downregulating ATF3, maintains epithelial junction integrity through RAC1 regulation, and its mRNA stability is controlled by METTL3/ELAVL1-dependent m6A modification [#11, #13, #15]. Biallelic loss-of-function DRG1 variants that impair GTPase activity and disrupt binding to the DFRP1 ortholog ZC3H15 cause a recessive neurodevelopmental disorder, and Drg1 knockout is lethal in mice, establishing the protein as essential for mammalian development [#14].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established that Drg1 ATPase activity is essential for a defined step of ribosome biogenesis, answering what cellular process this AAA-ATPase serves.\",\n      \"evidence\": \"Genetic inactivation and dominant-negative D2 domain mutant with subcellular fractionation in S. cerevisiae\",\n      \"pmids\": [\"17646390\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the direct substrate released\", \"Mechanism of substrate engagement unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved how Drg1 acts on pre-60S particles by identifying Rlp24 as the specific extracted substrate and dissecting the ordered D2-then-D1 hydrolysis cycle, answering the directionality and recruitment logic.\",\n      \"evidence\": \"In vitro reconstitution with purified pre-60S particles, ATPase assays, and domain mutagenesis\",\n      \"pmids\": [\"23185031\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of substrate threading not yet resolved\", \"Role of Nup116 interaction not structurally defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified diazaborine's mechanism of action as ATP-dependent binding into the D2 domain, validating Drg1 as a druggable target and confirming D2 hydrolysis as the critical step.\",\n      \"evidence\": \"Drug-target identification, biochemical inhibition assays, and ATPase domain mutagenesis in yeast\",\n      \"pmids\": [\"24371142\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural detail of the inhibited state addressed only later\", \"Selectivity over other AAA-ATPases not fully defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed the N-domain regulates ATPase activity via inter-domain communication with D1, answering how Drg1's catalytic cycle is internally coordinated.\",\n      \"evidence\": \"Mutagenesis of N-domain/D1 interface with ATPase and Rlp24-binding assays in yeast\",\n      \"pmids\": [\"28303975\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited structural validation in this study\", \"Physiological consequences of dysregulation not tested in vivo\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Provided the structural mechanism: cryo-EM revealed planar-to-helical hexamer transitions and a substrate-engaged spiral pore-loop staircase, establishing Drg1 as a polypeptide-threading unfoldase and explaining diazaborine inhibition.\",\n      \"evidence\": \"Cryo-EM in multiple nucleotide and inhibitor states with structure-based mutagenesis\",\n      \"pmids\": [\"36351914\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the threaded substrate region within pre-60S not defined\", \"Coupling to downstream maturation factors unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected the yeast Drg1 paradigm to humans by showing the metazoan AAA-ATPase SPATA5 evolved from Drg1 and performs cytoplasmic pre-60S maturation within the 55LCC complex.\",\n      \"evidence\": \"Interaction screen, cryo-EM, crystallography, and acute depletion with ATPase mutant swap-in (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.11.07.687187\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DRG1 itself studied as evolutionary ancestor rather than directly\", \"Preprint, not peer-reviewed\", \"Whether human DRG1 retains any pre-60S role unaddressed\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identified DFRP1 as the specific stabilizing partner of mammalian DRG1, answering how DRG1 protein levels are controlled.\",\n      \"evidence\": \"Co-immunoprecipitation, dfrp1 knockout cell lines, and immunofluorescence\",\n      \"pmids\": [\"15676025\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the ubiquitin ligase acting on DRG1 unknown\", \"Functional output of stabilization not yet defined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed the DRG1/DFRP1 complex co-sediments with polysomes whereas DRG2/DFRP2 does not, distinguishing DRG1 as the translation-associated paralog.\",\n      \"evidence\": \"Polysome fractionation and co-sedimentation in mammalian cells\",\n      \"pmids\": [\"19819225\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct role in translation not functionally demonstrated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined DRG1 as a potassium-dependent GTPase and pinpointed the DFRP domain as the 4-fold catalytic stimulator, establishing the enzymatic regulation of the mammalian protein.\",\n      \"evidence\": \"Purified recombinant GTPase assays with domain deletion and point mutants\",\n      \"pmids\": [\"23711155\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological GTPase substrate/effector unknown\", \"Cellular consequence of GTP hydrolysis not addressed here\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"First linked DRG1 to mitotic fidelity, showing it is a centrosome- and microtubule-associated protein required for spindle integrity in a p53-dependent checkpoint.\",\n      \"evidence\": \"Immunofluorescence, siRNA knockdown, ectopic overexpression, and flow cytometry with spindle inhibitors\",\n      \"pmids\": [\"15247272\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of p53 dependence unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Reconstituted DRG1's direct microtubule activities, showing it diffuses on, polymerizes, bundles and stabilizes microtubules independently of GTP hydrolysis, separating this function from its GTPase cycle.\",\n      \"evidence\": \"In vitro polymerization and TIRF assays, siRNA in HeLa, live imaging, and domain truncations\",\n      \"pmids\": [\"28855639\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How non-catalytic microtubule activity integrates with GTPase function unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Placed DRG1 downstream of PTEN/Akt signaling, showing PTEN transcriptionally upregulates DRG1, linking it to a tumor-suppressor pathway.\",\n      \"evidence\": \"PTEN overexpression/knockdown and Akt inhibitor treatment in prostate and breast cancer cells\",\n      \"pmids\": [\"15520163\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factor mediating PTEN-dependent induction unidentified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified ATF3 as a downstream effector, establishing transcriptional ATF3 repression as a mechanism of DRG1 metastasis suppression.\",\n      \"evidence\": \"Microarray, siRNA, ATF3 promoter luciferase assay, and in vivo SCID metastasis model\",\n      \"pmids\": [\"17178897\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which DRG1 represses the ATF3 promoter unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified a cytoplasmic DRG1–NADE interaction and a proliferation-promoting role antagonized by NADE, expanding DRG1's interactome.\",\n      \"evidence\": \"Co-IP, in vitro binding, domain mapping, and cell-cycle flow cytometry\",\n      \"pmids\": [\"16777077\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between binding and proliferation unresolved\", \"Single lab, limited depth\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established post-transcriptional control of DRG1, showing METTL3-deposited m6A and ELAVL1 binding stabilize DRG1 mRNA.\",\n      \"evidence\": \"m6A measurement, METTL3/ELAVL1 knockdown, and mRNA stability assays in osteosarcoma cells\",\n      \"pmids\": [\"32266933\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional output of DRG1 in osteosarcoma not mechanistically tied to m6A\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined a DRG1 role in epithelial barrier maintenance through RAC1 regulation, broadening its physiological function.\",\n      \"evidence\": \"Interactome MS, DRG1 silencing/overexpression, permeability assays, RAC1 inhibitor, and in vivo NEC model\",\n      \"pmids\": [\"33471252\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct biochemical link between DRG1 and RAC1 activation not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated evolutionary conservation of DRG1's monomeric state, DFRP1 complex formation, nucleic acid binding, and tubulin influence from sponge to human.\",\n      \"evidence\": \"Recombinant protein purification, binding assays, immunofluorescence, and α-tubulin dynamics assay\",\n      \"pmids\": [\"35790840\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biological significance of nonspecific nucleic acid binding unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established DRG1 as a Mendelian disease gene, showing biallelic loss-of-function variants impair GTPase activity and ZC3H15/DFRP1 binding and cause a recessive neurodevelopmental disorder, with mouse knockout lethal.\",\n      \"evidence\": \"Patient fibroblast analysis, GTPase assays on mutants, Co-IP binding, and mouse Drg1 knockout\",\n      \"pmids\": [\"37179472\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular pathway whose disruption causes neurodevelopmental phenotype unresolved\", \"Tissue-specific requirements not defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked DRG1 to cellular senescence via a NO2/ROS-induced interaction with CDK5 in bronchial epithelium.\",\n      \"evidence\": \"Co-IP, siRNA, NAC treatment, β-galactosidase and cell-cycle assays\",\n      \"pmids\": [\"42070819\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP for DRG1-CDK5 without reciprocal validation\", \"Indirect mechanistic placement\", \"Direct functional consequence of the interaction undefined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether mammalian DRG1 retains a direct role in cytoplasmic pre-60S ribosome maturation analogous to its yeast ortholog, and how its GTPase, microtubule, and ribosome-associated activities are integrated, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No human GTPase effector/substrate identified\", \"Relationship between DRG1 and the metazoan SPATA5/55LCC pre-60S machinery undefined\", \"Mechanism connecting molecular activities to the neurodevelopmental phenotype unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [6, 14]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [7, 8]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4, 17]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [7, 8]},\n      {\"term_id\": \"GO:0005840\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [7, 8]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"complexes\": [\"DRG1–DFRP1 complex\"],\n    \"partners\": [\"DFRP1\", \"ZC3H15\", \"Rlp24\", \"Nup116\", \"RAC1\", \"NADE\", \"CDK5\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}