{"gene":"ATRIP","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2001,"finding":"ATRIP is an ATR-interacting protein that is phosphorylated by ATR, regulates ATR expression, and is mutually dependent with ATR for stable expression; siRNA knockdown of ATRIP causes loss of both ATRIP and ATR protein and abolishes DNA damage checkpoint responses, establishing ATR and ATRIP as obligate partners.","method":"Co-immunoprecipitation, siRNA knockdown, Cre-mediated ATR deletion, checkpoint assays","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, genetic knockdown with defined checkpoint phenotype, replicated across multiple experiments in founding paper","pmids":["11721054"],"is_preprint":false},{"year":2003,"finding":"RPA-coated ssDNA is the critical structure that recruits the ATR-ATRIP complex to sites of DNA damage; ATRIP directly binds RPA-ssDNA in vitro, enabling ATR-ATRIP to associate with DNA and stimulate phosphorylation of Rad17; the yeast ATRIP ortholog Ddc2 is recruited to DSBs in an RPA-dependent manner, and the checkpoint-deficient RPA mutant rfa1-t11 is defective for recruiting Ddc2 both in vivo and in vitro.","method":"In vitro RPA-ssDNA binding assays, in vivo chromatin recruitment assays, checkpoint kinase assays, yeast genetics with rfa1-t11 mutant","journal":"Science","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro reconstitution combined with in vivo localization and genetic epistasis, replicated in human cells and yeast","pmids":["12791985"],"is_preprint":false},{"year":2004,"finding":"ATR exists as a monomer associated with ATRIP with moderate affinity; ATRIP stimulates ATR-mediated phosphorylation of RPA in a ssDNA-dependent manner, but both ATR alone and the ATR-ATRIP heterodimer bind naked or RPA-covered DNA with comparable affinities.","method":"In vitro kinase assays, DNA-binding assays, biochemical fractionation","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution assays, single lab, no mutagenesis validation","pmids":["14729973"],"is_preprint":false},{"year":2004,"finding":"ATR-ATRIP complex can bind ssDNA in two modes: a high-affinity RPA-dependent mode and a lower-affinity RPA-independent mode that requires an additional unidentified protein from HeLa nuclear extract; neither ATR nor ATRIP can bind DNA individually in this low-affinity mode.","method":"ssDNA-cellulose pulldown, chromatin association assays, nuclear extract complementation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — biochemical reconstitution with defined DNA substrates, single lab","pmids":["14724280"],"is_preprint":false},{"year":2004,"finding":"ATR-mediated phosphorylation of ATRIP at Ser-68 and Ser-72 occurs in response to genotoxic stimuli; phosphorylated ATRIP accumulates at DNA damage foci, but this phosphorylation is dispensable for ATRIP relocalization to foci and activation of downstream effectors.","method":"Mass spectrometry, phospho-specific antibodies, in vitro kinase assay, immunofluorescence","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vitro kinase assay with site-specific mutations, phospho-specific antibody validation, single lab","pmids":["15451423"],"is_preprint":false},{"year":2004,"finding":"ATR-ATRIP and Claspin collaborate in a multistep process for Chk1 activation: ATR-ATRIP bound to ssDNA/dsDNA junction templates shows higher kinase activity than on ssDNA alone, and Claspin strongly stimulates phosphorylation of Chk1 by activated ATR-ATRIP.","method":"Xenopus egg extract cell-free reconstitution, kinase assays with defined DNA templates, immunodepletion","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution with purified components and defined DNA templates, multiple orthogonal assays","pmids":["15371427"],"is_preprint":false},{"year":2004,"finding":"The N-terminal domain of ATRIP contributes to intranuclear relocalization to DNA damage-induced foci in an RPA-dependent manner even without ATR association, suggesting an ATR-independent localization function for this domain.","method":"Domain deletion/truncation constructs, immunofluorescence foci assays, co-immunoprecipitation","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single lab, localization assays with truncation mutants, no functional rescue","pmids":["15527801"],"is_preprint":false},{"year":2005,"finding":"The N-terminal domain of ATRIP is necessary and sufficient for interaction with RPA-ssDNA and for ATRIP accumulation into damage-induced foci; however, the ATRIP-RPA-ssDNA interaction is not absolutely essential for ATR activation because Chk1 phosphorylation occurs in cells expressing an ATRIP mutant that cannot bind RPA-ssDNA; ATR association is also required for proper ATRIP localization.","method":"Domain deletion mutants, immunofluorescence foci assays, Chk1 phosphorylation assays, complementation in ATRIP-depleted cells","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple ATRIP mutants tested with orthogonal readouts (localization and kinase signaling), single lab but rigorous dissection","pmids":["15743907"],"is_preprint":false},{"year":2005,"finding":"ATRIP binding to ATR is required for ATR to efficiently phosphorylate Chk1 in Xenopus egg extracts; stable DNA-binding domain and coiled-coil domain of ATRIP are dispensable for Chk1 phosphorylation on defined checkpoint-inducing templates; ATRIP adopts an oligomeric state in egg extracts dependent on binding to ATR.","method":"Xenopus egg extract reconstitution, ATRIP mutant constructs, Chk1 phosphorylation assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution with defined templates and multiple domain mutants, orthogonal assays","pmids":["16186122"],"is_preprint":false},{"year":2005,"finding":"The coiled-coil domain of ATRIP mediates ATRIP homodimerization/homo-oligomerization; this domain is essential for oligomerization, stable ATR binding, and accumulation of ATRIP at DNA lesions; replacing the coiled-coil with a heterologous dimerization domain restores stable ATR binding and localization, demonstrating that oligomerization per se (not the specific coiled-coil sequence) is required for ATR-dependent checkpoint signaling to Chk1.","method":"Co-immunoprecipitation, domain deletion/swap mutants, immunofluorescence, Chk1 phosphorylation assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, domain-swap rescue experiment, multiple orthogonal readouts","pmids":["16027118"],"is_preprint":false},{"year":2005,"finding":"The coiled-coil domain of ATRIP mediates self-dimerization in vivo and is required for stable translocation of the ATR-ATRIP complex to nuclear foci after genotoxic stress; dimerization-defective ATRIP compromises maintenance of replication forks during replication inhibitor treatment but does not impair the G2/M checkpoint after IR, revealing separable ATR-ATRIP functions.","method":"In vivo dimerization assays, immunofluorescence foci, DNA fiber assays, checkpoint assays","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multiple functional readouts with defined mutants, single lab","pmids":["16176973"],"is_preprint":false},{"year":2006,"finding":"TopBP1 activates the ATR-ATRIP kinase complex; recombinant TopBP1 induces a large increase in ATR kinase activity in both Xenopus and human systems; the ATR-activating domain of TopBP1 is a conserved segment distinct from BRCT repeats; a point mutation inactivating this domain renders egg extracts defective in checkpoint regulation.","method":"In vitro kinase assays with recombinant TopBP1, Xenopus egg extract checkpoint assays, domain mapping, point mutagenesis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with recombinant proteins, mutagenesis validation, replicated in both Xenopus and human cells","pmids":["16530042"],"is_preprint":false},{"year":2006,"finding":"ATRIP associates with RPA-ssDNA through multiple interactions: two major RPA-ssDNA-interacting domains flank the conserved coiled-coil domain; one internal region of ATRIP exhibits direct affinity for ssDNA; the N-terminus associates with RPA-ssDNA in two distinct ways, indicating dynamic and redundant interactions.","method":"Domain mapping, biochemical pulldown assays with RPA-ssDNA, ssDNA binding assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — systematic biochemical domain mapping, single lab","pmids":["16407120"],"is_preprint":false},{"year":2007,"finding":"A conserved checkpoint recruitment domain (CRD) at the N-terminus of ATRIP mediates the RPA interaction; mutations in the CRD of Saccharomyces cerevisiae Ddc2 disrupt Ddc2-RPA interaction, prevent proper localization to DNA breaks, sensitize yeast to DNA-damaging agents, and partially compromise checkpoint signaling; TopBP1-mediated ATR activation can occur independently of ATRIP-RPA interaction.","method":"Biochemical mapping, NMR, mutagenesis, yeast genetics, checkpoint assays, DNA damage sensitivity assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure combined with mutagenesis, yeast genetic validation, multiple orthogonal readouts","pmids":["17339343"],"is_preprint":false},{"year":2007,"finding":"CDK2-cyclin A phosphorylates ATRIP at S224 in vitro and in cells in a cell cycle-dependent manner; mutation of S224 to alanine causes a defect in ATR-ATRIP-dependent G2/M checkpoint maintenance after IR and UV radiation.","method":"Mass spectrometry phosphosite identification, in vitro kinase assay with CDK2-cyclin A, phospho-specific antibodies, CDK2 inhibitor treatment, checkpoint assays with S224A mutant","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro kinase assay, specific mutagenesis, pharmacological validation, functional checkpoint assay","pmids":["17638878"],"is_preprint":false},{"year":2008,"finding":"ATRIP contains a TopBP1-interacting region required for TopBP1-ATR association and TopBP1-mediated ATR activation; ATR contains a PIKK Regulatory Domain (PRD) that is critical for activation by TopBP1 (mutations abolish activation without affecting basal kinase activity); both are required for checkpoint signaling and cellular viability after replication stress; the ATRIP TopBP1-interacting region is functionally conserved in yeast Ddc2.","method":"Domain mapping, site-directed mutagenesis, in vitro kinase assays, cellular complementation assays, yeast genetic epistasis","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — mutagenesis of both ATR and ATRIP with in vitro kinase validation and cellular rescue, conserved in yeast, multiple orthogonal methods","pmids":["18519640"],"is_preprint":false},{"year":2012,"finding":"ATRIP is crucial for DNA damage-induced FANCD2 monoubiquitination and FANCI phosphorylation; ATR phosphorylates recombinant FANCI in vitro, facilitated by FANCD2; the RPA-binding region of ATRIP (but not the TopBP1-binding region) is required for FANCD2 monoubiquitination, whereas Chk1 phosphorylation requires both domains.","method":"Conditional ATRIP-deficient DT40 cells, in vitro kinase assay with recombinant FANCI, domain deletion mutants, immunoblotting","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro kinase reconstitution, conditional knockout system, domain-specific mutants dissecting pathway","pmids":["22258451"],"is_preprint":false},{"year":2013,"finding":"Nek1 kinase associates with ATR-ATRIP, maintains ATRIP protein levels, and promotes ATR-ATRIP association and basal ATR kinase activity even in undamaged cells; upon DNA damage, Nek1 is required for efficient phosphorylation of ATR substrates and ATR autophosphorylation at T1989; Nek1's promotion of ATR activation requires Nek1 kinase activity and its interaction with ATR-ATRIP.","method":"Co-immunoprecipitation, Nek1 siRNA knockdown, ATR kinase activity assays, ATR autophosphorylation assays, kinase-dead Nek1 mutant","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, kinase-dead mutant, multiple ATR substrates assayed, mechanistic dissection of basal vs. damage-induced activity","pmids":["23345434"],"is_preprint":false},{"year":2013,"finding":"The FA core complex enhances ATRIP binding and localization within damaged chromatin; in FA core complex-deficient cells, ATR-mediated phosphorylation of both ATRIP and FANCI is defective; canonical ATR activation via RAD17 and TOPBP1 is largely dispensable for FA pathway activation.","method":"Chromatin fractionation, conditional ATRIP-deficient DT40 cells, double mutant epistasis (RAD17/FANCD2), immunoblotting","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — chromatin binding assays and genetic epistasis in DT40 cells, single lab","pmids":["23723247"],"is_preprint":false},{"year":2013,"finding":"The BRCA1 BRCT domains bind an ATRIP phosphopeptide (pS238-containing motif 235-PEACpSPQFG-243); crystal structures at 1.75 Å resolution reveal that pSer and Phe(+3) anchor the ATRIP peptide into the BRCT binding groove, with Gln(+2) accommodated through a conformational change of BRCA1 E1698.","method":"X-ray crystallography at 1.75 Å, isothermal titration calorimetry","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with ITC binding validation, rigorous structural determination","pmids":["24073851"],"is_preprint":false},{"year":2014,"finding":"ATRIP is SUMOylated by SUMO2/3 at K234 and K289; an ATRIP SUMOylation mutant fails to localize efficiently to DNA damage sites and support ATR activation; SUMOylation promotes simultaneous interaction with multiple ATRIP partners including ATR, RPA70, TopBP1, and the MRE11-RAD50-NBS1 complex, and these partners display affinity for SUMO2 chains in vitro; fusion of a SUMO2 chain to the ATRIP SUMOylation mutant partially rescues its defects.","method":"SUMO site identification, ATRIP SUMOylation mutants, co-immunoprecipitation, in vitro SUMO-binding assays, immunofluorescence, SUMO2-ATRIP fusion rescue","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — site-specific mutagenesis, in vitro SUMO binding, rescue experiment, multiple interacting proteins tested with orthogonal methods","pmids":["24990965"],"is_preprint":false},{"year":2016,"finding":"SIRT2 deacetylates ATRIP at lysine K32 in response to replication stress; K32 deacetylation by SIRT2 promotes ATRIP accumulation at DNA damage sites, binding to RPA-ssDNA, ATR autophosphorylation, and ATR checkpoint signaling, as well as DNA replication fork progression and recovery.","method":"Co-immunoprecipitation, in vitro deacetylation assays, K32R/K32Q acetylation mutants, immunofluorescence foci, ATR autophosphorylation and Chk1 phosphorylation assays, DNA fiber assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — identified writer (SIRT2), mapped site (K32), validated with acetylation mimetic and non-acetylatable mutants, multiple functional readouts","pmids":["26854234"],"is_preprint":false},{"year":2017,"finding":"Cryo-EM structure of the human ATR-ATRIP complex at 4.7 Å overall (3.9 Å for ATR C-terminal catalytic core) reveals a hollow 'heart'-shaped dimer of heterodimers; ATRIP contains 14 HEAT repeats in an extended 'S' shape; conformational flexibility of ATR allows ATRIP to lock the N-termini of two ATR monomers; catalytic pockets face outward without inhibitory occlusion.","method":"Cryo-electron microscopy, atomic model building","journal":"Cell research","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure at near-atomic resolution with atomic model, provides structural basis for complex assembly","pmids":["29271416"],"is_preprint":false},{"year":2017,"finding":"Cryo-EM structure of yeast Mec1-Ddc2 (ATR-ATRIP ortholog) at 3.9 Å reveals the complex forms a dimer of heterodimers through Mec1 PRD/FAT domains and the Ddc2 coiled-coil domain; the PRD inhibits the Mec1 activation loop, establishing an allosteric mechanism of kinase activation; PRD and Bridge domains constitute critical regulatory sites.","method":"Cryo-electron microscopy at 3.9 Å resolution","journal":"Science","confidence":"High","confidence_rationale":"Tier 1 / Strong — near-atomic cryo-EM structure of intact complex revealing allosteric regulatory mechanism","pmids":["29191911"],"is_preprint":false},{"year":2019,"finding":"ZFP161 acts as a scaffolding protein that facilitates interaction between RPA and ATR/ATRIP; ZFP161 binds RPA and ATR/ATRIP through distinct regions and stabilizes the RPA-ATR-ATRIP complex at stalled replication forks, promoting ATR-Chk1 signaling.","method":"Co-immunoprecipitation, domain-specific binding assays, ZFP161 knockout mice, ATR/Chk1 signaling assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — co-IP with domain mapping, knockout mouse validation, single lab","pmids":["31757956"],"is_preprint":false},{"year":2017,"finding":"ATRIP directly interacts with MCM2, MCM3, MCM6, and MCM7; downregulation of MCM2 and MCM6 significantly reduces ATRIP chromatin loading; downregulation of MCM2 decreases ATRIP phosphorylation at S224 in a dose-dependent manner.","method":"Mass spectrometry, co-immunoprecipitation, GST pulldown, shRNA knockdown, chromatin fractionation","journal":"Die Pharmazie","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — GST pulldown and co-IP establish direct interaction, chromatin fractionation shows functional consequence, single lab","pmids":["29442041"],"is_preprint":false},{"year":2023,"finding":"APE1 directly associates with ssDNA and recruits ATRIP onto ssDNA in an RPA-independent manner; the N-terminal motif of APE1 is required and sufficient for APE1-ATRIP interaction in vitro; this APE1-ATRIP interaction is required for ATRIP recruitment to ssDNA and ATR-Chk1 DDR pathway activation in Xenopus egg extracts; APE1 also directly associates with RPA70 and RPA32 via two distinct motifs.","method":"In vitro pulldown, Xenopus egg extract reconstitution, domain mapping with N-terminal APE1 motif mutants, Chk1 phosphorylation assays","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 1-2 / Weak — in vitro reconstitution with purified proteins and egg extracts, domain mapping, single lab","pmids":["37216274"],"is_preprint":false},{"year":2025,"finding":"REV7 directly binds ATRIP through a defined REV7-interaction motif in ATRIP; mutation of this motif abrogates the REV7-ATRIP interaction in vitro and in cells; REV7 inhibits ATR-mediated phosphorylation of substrates including p53 in vitro; disruption of the REV7-ATRIP interaction enhances CHK1 phosphorylation at Ser317 in cells, establishing REV7 as a negative regulator of ATR signaling.","method":"In vitro binding assays, in vitro kinase assays, site-directed mutagenesis of REV7-interaction motif, cellular CHK1 phosphorylation assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro kinase assay, defined interaction motif mutagenesis validated both in vitro and in cells, multiple substrates tested","pmids":["41562258"],"is_preprint":false},{"year":2025,"finding":"Cryo-EM structures of human ATR-ATRIP complex at ~3 Å overall resolution in the presence of ATR inhibitors VE-822 and RP-3500 reveal near-complete atomic model including subunit stoichiometry (dimer of heterodimers), intramolecular and intermolecular interactions, and PRD regulatory insertion; one ATR-ATRIP complex binds four VE-822 molecules (two in active site, two at ATR-ATR dimer interface); RP-3500 binding depends on two bound water molecules.","method":"Cryo-electron microscopy at ~3 Å resolution with two different inhibitor complexes","journal":"Science bulletin","confidence":"High","confidence_rationale":"Tier 1 / Strong — near-atomic cryo-EM structures with two inhibitors providing near-complete atomic model and mechanistic insight into inhibition","pmids":["40379520"],"is_preprint":false}],"current_model":"ATRIP is the obligate regulatory partner of ATR kinase that forms a dimer-of-heterodimers complex (structurally resolved by cryo-EM); its N-terminal checkpoint recruitment domain (CRD) directly binds RPA-coated ssDNA to recruit ATR-ATRIP to stalled replication forks and DNA damage sites, while its coiled-coil domain mediates ATRIP homo-oligomerization essential for stable ATR binding and checkpoint signaling; a TopBP1-interacting region in ATRIP cooperates with the ATR PRD to enable allosteric kinase activation by TopBP1; ATR-ATRIP activity is further modulated by multiple post-translational modifications (CDK2-dependent S224 phosphorylation, SIRT2-dependent K32 deacetylation, SUMO2/3 modification at K234/K289, and ATR-dependent phosphorylation at S68/S72) and by interacting partners including Nek1 (positive regulator that primes ATR-ATRIP stability and activity), REV7 (negative regulator that inhibits ATR kinase activity by direct ATRIP binding), ZFP161 (scaffolds RPA-ATR-ATRIP assembly), and the FA core complex (enhances ATRIP chromatin loading); through these mechanisms ATRIP coordinates ATR-dependent phosphorylation of Chk1, FANCI, RPA, and other substrates to enforce checkpoint responses to replication stress and DNA damage."},"narrative":{"mechanistic_narrative":"ATRIP is the obligate regulatory partner of the ATR kinase, and the two proteins are mutually dependent for stable expression and for mounting DNA damage checkpoint responses [PMID:11721054]. ATRIP localizes the complex to sites of genotoxic stress: its N-terminal checkpoint recruitment domain (CRD) directly binds RPA-coated ssDNA, the structure that recruits ATR-ATRIP to DNA damage and stimulates downstream checkpoint kinase activity [PMID:12791985, PMID:17339343]. RPA-ssDNA engagement is mediated by multiple, redundant interactions flanking the conserved coiled-coil, which itself drives ATRIP homo-oligomerization required for stable ATR binding and accumulation at lesions; oligomerization per se, rather than the specific coiled-coil sequence, is the essential feature [PMID:16027118, PMID:16407120]. Structurally, ATR-ATRIP assembles as a heart-shaped dimer of heterodimers in which an extended HEAT-repeat ATRIP locks the N-termini of two ATR monomers [PMID:29271416]. Once recruited, the complex is allosterically activated by TopBP1, which engages a dedicated TopBP1-interacting region in ATRIP that cooperates with the ATR PIKK regulatory domain (PRD) to switch on kinase activity, enabling phosphorylation of Chk1 and other substrates [PMID:16530042, PMID:18519640]. Distinct ATRIP domains route the complex to distinct outputs: the RPA-binding region supports FANCD2 monoubiquitination and FANCI phosphorylation in the Fanconi anemia pathway, whereas full Chk1 activation requires both the RPA- and TopBP1-binding regions [PMID:22258451]. ATRIP activity is further tuned by post-translational modifications, including CDK2-cyclin A phosphorylation at S224 controlling G2/M checkpoint maintenance, SIRT2-dependent K32 deacetylation promoting RPA-ssDNA binding, and SUMO2/3 modification at K234/K289 enabling coordinated assembly with ATR, RPA, TopBP1, and MRN [PMID:17638878, PMID:26854234, PMID:24990965], and by interacting partners that act as positive regulators (Nek1, ZFP161) or as a negative regulator (REV7, which directly binds ATRIP to inhibit ATR kinase activity) [PMID:23345434, PMID:31757956, PMID:41562258].","teleology":[{"year":2001,"claim":"Established that ATR does not function alone but requires a dedicated partner, defining ATRIP as the obligate co-factor of ATR.","evidence":"Co-immunoprecipitation, siRNA knockdown, and checkpoint assays in human cells","pmids":["11721054"],"confidence":"High","gaps":["Did not define how the complex is recruited to DNA","Did not map interaction surfaces or domains"]},{"year":2003,"claim":"Identified the physical signal that recruits ATR-ATRIP, showing RPA-coated ssDNA as the structure bound by ATRIP to localize the kinase to damage.","evidence":"In vitro RPA-ssDNA binding, in vivo recruitment assays, and yeast rfa1-t11 genetics","pmids":["12791985"],"confidence":"High","gaps":["Did not localize the RPA-binding region within ATRIP","Did not establish whether RPA binding is sufficient for kinase activation"]},{"year":2004,"claim":"Dissected the biochemistry of ATR-ATRIP DNA binding and activation, showing ATRIP stimulates ssDNA-dependent substrate phosphorylation and that ssDNA/dsDNA junctions plus Claspin promote Chk1 activation.","evidence":"In vitro kinase and DNA-binding assays, Xenopus egg extract reconstitution, ATRIP phosphosite mapping (S68/S72)","pmids":["14729973","14724280","15371427","15451423"],"confidence":"High","gaps":["RPA-independent low-affinity binding required an unidentified factor","Function of S68/S72 phosphorylation beyond foci accumulation unclear"]},{"year":2005,"claim":"Resolved the modular architecture of ATRIP, separating an N-terminal RPA-ssDNA-binding/foci-recruitment function from a coiled-coil oligomerization function required for stable ATR binding.","evidence":"Domain deletion and domain-swap mutants, Chk1 phosphorylation, foci and DNA fiber assays in human cells and egg extracts","pmids":["15527801","15743907","16186122","16027118","16176973"],"confidence":"High","gaps":["Showed RPA binding is not strictly essential for Chk1 activation, leaving the activation trigger unresolved","Separable replication-fork vs. G2/M functions not mechanistically explained"]},{"year":2006,"claim":"Defined the allosteric activation mechanism, identifying TopBP1 as the direct kinase activator of ATR-ATRIP and mapping multiple redundant RPA-ssDNA contacts in ATRIP.","evidence":"In vitro kinase assays with recombinant TopBP1, point mutagenesis, domain mapping of RPA-ssDNA contacts","pmids":["16530042","16407120"],"confidence":"High","gaps":["Did not identify the ATRIP region contacting TopBP1","Did not define the structural basis of activation"]},{"year":2007,"claim":"Pinpointed the conserved checkpoint recruitment domain (CRD) mediating RPA binding and a CDK2 phosphosite (S224) regulating the checkpoint, linking ATRIP function to cell-cycle control.","evidence":"NMR and mutagenesis of yeast Ddc2 CRD, CDK2-cyclin A kinase assays and S224A checkpoint assays","pmids":["17339343","17638878"],"confidence":"High","gaps":["CRD/RPA disruption only partially compromised checkpoint signaling","TopBP1-mediated activation can bypass RPA binding"]},{"year":2008,"claim":"Mapped the ATRIP TopBP1-interacting region and showed it cooperates with the ATR PRD, providing the molecular basis for TopBP1-dependent kinase activation.","evidence":"Domain mapping, site-directed mutagenesis of ATR and ATRIP, in vitro kinase and cellular rescue, yeast epistasis","pmids":["18519640"],"confidence":"High","gaps":["Structural mechanism of PRD-TopBP1 cooperation not yet resolved"]},{"year":2012,"claim":"Showed ATRIP domains route signaling to distinct outputs, with the RPA-binding region required for FANCD2/FANCI activation in the Fanconi anemia pathway.","evidence":"Conditional ATRIP-deficient DT40 cells, in vitro kinase assays on recombinant FANCI, domain deletion mutants","pmids":["22258451"],"confidence":"High","gaps":["How FANCD2 facilitates FANCI phosphorylation mechanistically unclear","Did not address structural basis of domain-specific output"]},{"year":2013,"claim":"Expanded the regulatory network of ATRIP, identifying Nek1 and the FA core complex as positive regulators of ATRIP stability and chromatin loading, and BRCA1 BRCT binding to a phospho-ATRIP motif.","evidence":"Co-IP, siRNA knockdown, kinase assays, chromatin fractionation in DT40 cells, BRCA1-ATRIP phosphopeptide crystal structure with ITC","pmids":["23345434","23723247","24073851"],"confidence":"High","gaps":["Functional role of BRCA1-ATRIP pS238 binding in vivo not established","FA core complex mechanism distinct from canonical RAD17/TOPBP1 not fully defined"]},{"year":2014,"claim":"Established SUMO2/3 modification of ATRIP as a coordinating switch that promotes simultaneous assembly with multiple partners at damage sites.","evidence":"SUMO site mapping (K234/K289), mutants, in vitro SUMO-binding, and SUMO2-fusion rescue","pmids":["24990965"],"confidence":"High","gaps":["SUMO ligase responsible for ATRIP modification not identified","Quantitative contribution to checkpoint signaling unresolved"]},{"year":2016,"claim":"Added acetylation control, showing SIRT2-dependent K32 deacetylation promotes ATRIP recruitment, RPA-ssDNA binding, and replication fork recovery.","evidence":"In vitro deacetylation, K32R/K32Q mutants, foci, ATR autophosphorylation, and DNA fiber assays","pmids":["26854234"],"confidence":"High","gaps":["Acetyltransferase opposing SIRT2 not identified","How K32 status alters RPA-ssDNA affinity structurally unknown"]},{"year":2017,"claim":"Provided the first structural views of ATR-ATRIP and the orthologous Mec1-Ddc2 as dimers of heterodimers, revealing how ATRIP organizes the complex and how the PRD imposes allosteric kinase regulation.","evidence":"Cryo-EM of human ATR-ATRIP (4.7 Å) and yeast Mec1-Ddc2 (3.9 Å); ATRIP-MCM interaction mapping by MS/pulldown","pmids":["29271416","29191911","29442041"],"confidence":"High","gaps":["Limited resolution of human structure left ATRIP details incomplete","Functional significance of ATRIP-MCM interaction only partially defined"]},{"year":2019,"claim":"Identified ZFP161 as a scaffold that stabilizes the RPA-ATR-ATRIP assembly at stalled forks, extending the list of positive recruitment factors.","evidence":"Co-IP, domain mapping, ZFP161 knockout mice, ATR-Chk1 signaling assays","pmids":["31757956"],"confidence":"Medium","gaps":["Single lab; structural basis of scaffolding undefined","Generality across damage types not established"]},{"year":2023,"claim":"Revealed an RPA-independent recruitment route, with APE1 directly recruiting ATRIP to ssDNA to activate the ATR-Chk1 pathway.","evidence":"In vitro pulldown, Xenopus egg extract reconstitution, APE1 N-terminal motif mutagenesis, Chk1 phosphorylation","pmids":["37216274"],"confidence":"Medium","gaps":["Single lab; in vivo importance in human cells not established","Relationship to canonical RPA-dependent recruitment unclear"]},{"year":2025,"claim":"Identified REV7 as a direct negative regulator binding a defined ATRIP motif to inhibit ATR kinase activity, and produced near-atomic inhibitor-bound structures of the complex.","evidence":"In vitro binding and kinase assays, REV7-interaction motif mutagenesis, cellular CHK1 assays; cryo-EM at ~3 Å with VE-822 and RP-3500","pmids":["41562258","40379520"],"confidence":"High","gaps":["Cellular conditions governing REV7-mediated inhibition not fully defined","How inhibitor binding relates to physiological activation states partially resolved"]},{"year":null,"claim":"How the multiple ATRIP recruitment routes (RPA-dependent, APE1-dependent, FA-complex-dependent) and the layered PTMs and partner interactions are integrated to set ATR activity thresholds in vivo remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified quantitative model of recruitment vs. activation","Spatiotemporal hierarchy of PTMs and partner binding not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[1,3,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,9,15]},{"term_id":"GO:0098772","term_label":"molecular function regulator 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    \"method\": \"Co-immunoprecipitation, siRNA knockdown, Cre-mediated ATR deletion, checkpoint assays\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, genetic knockdown with defined checkpoint phenotype, replicated across multiple experiments in founding paper\",\n      \"pmids\": [\"11721054\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"RPA-coated ssDNA is the critical structure that recruits the ATR-ATRIP complex to sites of DNA damage; ATRIP directly binds RPA-ssDNA in vitro, enabling ATR-ATRIP to associate with DNA and stimulate phosphorylation of Rad17; the yeast ATRIP ortholog Ddc2 is recruited to DSBs in an RPA-dependent manner, and the checkpoint-deficient RPA mutant rfa1-t11 is defective for recruiting Ddc2 both in vivo and in vitro.\",\n      \"method\": \"In vitro RPA-ssDNA binding assays, in vivo chromatin recruitment assays, checkpoint kinase assays, yeast genetics with rfa1-t11 mutant\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro reconstitution combined with in vivo localization and genetic epistasis, replicated in human cells and yeast\",\n      \"pmids\": [\"12791985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"ATR exists as a monomer associated with ATRIP with moderate affinity; ATRIP stimulates ATR-mediated phosphorylation of RPA in a ssDNA-dependent manner, but both ATR alone and the ATR-ATRIP heterodimer bind naked or RPA-covered DNA with comparable affinities.\",\n      \"method\": \"In vitro kinase assays, DNA-binding assays, biochemical fractionation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution assays, single lab, no mutagenesis validation\",\n      \"pmids\": [\"14729973\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"ATR-ATRIP complex can bind ssDNA in two modes: a high-affinity RPA-dependent mode and a lower-affinity RPA-independent mode that requires an additional unidentified protein from HeLa nuclear extract; neither ATR nor ATRIP can bind DNA individually in this low-affinity mode.\",\n      \"method\": \"ssDNA-cellulose pulldown, chromatin association assays, nuclear extract complementation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — biochemical reconstitution with defined DNA substrates, single lab\",\n      \"pmids\": [\"14724280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"ATR-mediated phosphorylation of ATRIP at Ser-68 and Ser-72 occurs in response to genotoxic stimuli; phosphorylated ATRIP accumulates at DNA damage foci, but this phosphorylation is dispensable for ATRIP relocalization to foci and activation of downstream effectors.\",\n      \"method\": \"Mass spectrometry, phospho-specific antibodies, in vitro kinase assay, immunofluorescence\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vitro kinase assay with site-specific mutations, phospho-specific antibody validation, single lab\",\n      \"pmids\": [\"15451423\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"ATR-ATRIP and Claspin collaborate in a multistep process for Chk1 activation: ATR-ATRIP bound to ssDNA/dsDNA junction templates shows higher kinase activity than on ssDNA alone, and Claspin strongly stimulates phosphorylation of Chk1 by activated ATR-ATRIP.\",\n      \"method\": \"Xenopus egg extract cell-free reconstitution, kinase assays with defined DNA templates, immunodepletion\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution with purified components and defined DNA templates, multiple orthogonal assays\",\n      \"pmids\": [\"15371427\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The N-terminal domain of ATRIP contributes to intranuclear relocalization to DNA damage-induced foci in an RPA-dependent manner even without ATR association, suggesting an ATR-independent localization function for this domain.\",\n      \"method\": \"Domain deletion/truncation constructs, immunofluorescence foci assays, co-immunoprecipitation\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, localization assays with truncation mutants, no functional rescue\",\n      \"pmids\": [\"15527801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The N-terminal domain of ATRIP is necessary and sufficient for interaction with RPA-ssDNA and for ATRIP accumulation into damage-induced foci; however, the ATRIP-RPA-ssDNA interaction is not absolutely essential for ATR activation because Chk1 phosphorylation occurs in cells expressing an ATRIP mutant that cannot bind RPA-ssDNA; ATR association is also required for proper ATRIP localization.\",\n      \"method\": \"Domain deletion mutants, immunofluorescence foci assays, Chk1 phosphorylation assays, complementation in ATRIP-depleted cells\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple ATRIP mutants tested with orthogonal readouts (localization and kinase signaling), single lab but rigorous dissection\",\n      \"pmids\": [\"15743907\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ATRIP binding to ATR is required for ATR to efficiently phosphorylate Chk1 in Xenopus egg extracts; stable DNA-binding domain and coiled-coil domain of ATRIP are dispensable for Chk1 phosphorylation on defined checkpoint-inducing templates; ATRIP adopts an oligomeric state in egg extracts dependent on binding to ATR.\",\n      \"method\": \"Xenopus egg extract reconstitution, ATRIP mutant constructs, Chk1 phosphorylation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution with defined templates and multiple domain mutants, orthogonal assays\",\n      \"pmids\": [\"16186122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The coiled-coil domain of ATRIP mediates ATRIP homodimerization/homo-oligomerization; this domain is essential for oligomerization, stable ATR binding, and accumulation of ATRIP at DNA lesions; replacing the coiled-coil with a heterologous dimerization domain restores stable ATR binding and localization, demonstrating that oligomerization per se (not the specific coiled-coil sequence) is required for ATR-dependent checkpoint signaling to Chk1.\",\n      \"method\": \"Co-immunoprecipitation, domain deletion/swap mutants, immunofluorescence, Chk1 phosphorylation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, domain-swap rescue experiment, multiple orthogonal readouts\",\n      \"pmids\": [\"16027118\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The coiled-coil domain of ATRIP mediates self-dimerization in vivo and is required for stable translocation of the ATR-ATRIP complex to nuclear foci after genotoxic stress; dimerization-defective ATRIP compromises maintenance of replication forks during replication inhibitor treatment but does not impair the G2/M checkpoint after IR, revealing separable ATR-ATRIP functions.\",\n      \"method\": \"In vivo dimerization assays, immunofluorescence foci, DNA fiber assays, checkpoint assays\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multiple functional readouts with defined mutants, single lab\",\n      \"pmids\": [\"16176973\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TopBP1 activates the ATR-ATRIP kinase complex; recombinant TopBP1 induces a large increase in ATR kinase activity in both Xenopus and human systems; the ATR-activating domain of TopBP1 is a conserved segment distinct from BRCT repeats; a point mutation inactivating this domain renders egg extracts defective in checkpoint regulation.\",\n      \"method\": \"In vitro kinase assays with recombinant TopBP1, Xenopus egg extract checkpoint assays, domain mapping, point mutagenesis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with recombinant proteins, mutagenesis validation, replicated in both Xenopus and human cells\",\n      \"pmids\": [\"16530042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ATRIP associates with RPA-ssDNA through multiple interactions: two major RPA-ssDNA-interacting domains flank the conserved coiled-coil domain; one internal region of ATRIP exhibits direct affinity for ssDNA; the N-terminus associates with RPA-ssDNA in two distinct ways, indicating dynamic and redundant interactions.\",\n      \"method\": \"Domain mapping, biochemical pulldown assays with RPA-ssDNA, ssDNA binding assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — systematic biochemical domain mapping, single lab\",\n      \"pmids\": [\"16407120\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"A conserved checkpoint recruitment domain (CRD) at the N-terminus of ATRIP mediates the RPA interaction; mutations in the CRD of Saccharomyces cerevisiae Ddc2 disrupt Ddc2-RPA interaction, prevent proper localization to DNA breaks, sensitize yeast to DNA-damaging agents, and partially compromise checkpoint signaling; TopBP1-mediated ATR activation can occur independently of ATRIP-RPA interaction.\",\n      \"method\": \"Biochemical mapping, NMR, mutagenesis, yeast genetics, checkpoint assays, DNA damage sensitivity assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure combined with mutagenesis, yeast genetic validation, multiple orthogonal readouts\",\n      \"pmids\": [\"17339343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CDK2-cyclin A phosphorylates ATRIP at S224 in vitro and in cells in a cell cycle-dependent manner; mutation of S224 to alanine causes a defect in ATR-ATRIP-dependent G2/M checkpoint maintenance after IR and UV radiation.\",\n      \"method\": \"Mass spectrometry phosphosite identification, in vitro kinase assay with CDK2-cyclin A, phospho-specific antibodies, CDK2 inhibitor treatment, checkpoint assays with S224A mutant\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro kinase assay, specific mutagenesis, pharmacological validation, functional checkpoint assay\",\n      \"pmids\": [\"17638878\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ATRIP contains a TopBP1-interacting region required for TopBP1-ATR association and TopBP1-mediated ATR activation; ATR contains a PIKK Regulatory Domain (PRD) that is critical for activation by TopBP1 (mutations abolish activation without affecting basal kinase activity); both are required for checkpoint signaling and cellular viability after replication stress; the ATRIP TopBP1-interacting region is functionally conserved in yeast Ddc2.\",\n      \"method\": \"Domain mapping, site-directed mutagenesis, in vitro kinase assays, cellular complementation assays, yeast genetic epistasis\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — mutagenesis of both ATR and ATRIP with in vitro kinase validation and cellular rescue, conserved in yeast, multiple orthogonal methods\",\n      \"pmids\": [\"18519640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ATRIP is crucial for DNA damage-induced FANCD2 monoubiquitination and FANCI phosphorylation; ATR phosphorylates recombinant FANCI in vitro, facilitated by FANCD2; the RPA-binding region of ATRIP (but not the TopBP1-binding region) is required for FANCD2 monoubiquitination, whereas Chk1 phosphorylation requires both domains.\",\n      \"method\": \"Conditional ATRIP-deficient DT40 cells, in vitro kinase assay with recombinant FANCI, domain deletion mutants, immunoblotting\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro kinase reconstitution, conditional knockout system, domain-specific mutants dissecting pathway\",\n      \"pmids\": [\"22258451\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Nek1 kinase associates with ATR-ATRIP, maintains ATRIP protein levels, and promotes ATR-ATRIP association and basal ATR kinase activity even in undamaged cells; upon DNA damage, Nek1 is required for efficient phosphorylation of ATR substrates and ATR autophosphorylation at T1989; Nek1's promotion of ATR activation requires Nek1 kinase activity and its interaction with ATR-ATRIP.\",\n      \"method\": \"Co-immunoprecipitation, Nek1 siRNA knockdown, ATR kinase activity assays, ATR autophosphorylation assays, kinase-dead Nek1 mutant\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, kinase-dead mutant, multiple ATR substrates assayed, mechanistic dissection of basal vs. damage-induced activity\",\n      \"pmids\": [\"23345434\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The FA core complex enhances ATRIP binding and localization within damaged chromatin; in FA core complex-deficient cells, ATR-mediated phosphorylation of both ATRIP and FANCI is defective; canonical ATR activation via RAD17 and TOPBP1 is largely dispensable for FA pathway activation.\",\n      \"method\": \"Chromatin fractionation, conditional ATRIP-deficient DT40 cells, double mutant epistasis (RAD17/FANCD2), immunoblotting\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — chromatin binding assays and genetic epistasis in DT40 cells, single lab\",\n      \"pmids\": [\"23723247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The BRCA1 BRCT domains bind an ATRIP phosphopeptide (pS238-containing motif 235-PEACpSPQFG-243); crystal structures at 1.75 Å resolution reveal that pSer and Phe(+3) anchor the ATRIP peptide into the BRCT binding groove, with Gln(+2) accommodated through a conformational change of BRCA1 E1698.\",\n      \"method\": \"X-ray crystallography at 1.75 Å, isothermal titration calorimetry\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with ITC binding validation, rigorous structural determination\",\n      \"pmids\": [\"24073851\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ATRIP is SUMOylated by SUMO2/3 at K234 and K289; an ATRIP SUMOylation mutant fails to localize efficiently to DNA damage sites and support ATR activation; SUMOylation promotes simultaneous interaction with multiple ATRIP partners including ATR, RPA70, TopBP1, and the MRE11-RAD50-NBS1 complex, and these partners display affinity for SUMO2 chains in vitro; fusion of a SUMO2 chain to the ATRIP SUMOylation mutant partially rescues its defects.\",\n      \"method\": \"SUMO site identification, ATRIP SUMOylation mutants, co-immunoprecipitation, in vitro SUMO-binding assays, immunofluorescence, SUMO2-ATRIP fusion rescue\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — site-specific mutagenesis, in vitro SUMO binding, rescue experiment, multiple interacting proteins tested with orthogonal methods\",\n      \"pmids\": [\"24990965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"SIRT2 deacetylates ATRIP at lysine K32 in response to replication stress; K32 deacetylation by SIRT2 promotes ATRIP accumulation at DNA damage sites, binding to RPA-ssDNA, ATR autophosphorylation, and ATR checkpoint signaling, as well as DNA replication fork progression and recovery.\",\n      \"method\": \"Co-immunoprecipitation, in vitro deacetylation assays, K32R/K32Q acetylation mutants, immunofluorescence foci, ATR autophosphorylation and Chk1 phosphorylation assays, DNA fiber assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — identified writer (SIRT2), mapped site (K32), validated with acetylation mimetic and non-acetylatable mutants, multiple functional readouts\",\n      \"pmids\": [\"26854234\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Cryo-EM structure of the human ATR-ATRIP complex at 4.7 Å overall (3.9 Å for ATR C-terminal catalytic core) reveals a hollow 'heart'-shaped dimer of heterodimers; ATRIP contains 14 HEAT repeats in an extended 'S' shape; conformational flexibility of ATR allows ATRIP to lock the N-termini of two ATR monomers; catalytic pockets face outward without inhibitory occlusion.\",\n      \"method\": \"Cryo-electron microscopy, atomic model building\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure at near-atomic resolution with atomic model, provides structural basis for complex assembly\",\n      \"pmids\": [\"29271416\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Cryo-EM structure of yeast Mec1-Ddc2 (ATR-ATRIP ortholog) at 3.9 Å reveals the complex forms a dimer of heterodimers through Mec1 PRD/FAT domains and the Ddc2 coiled-coil domain; the PRD inhibits the Mec1 activation loop, establishing an allosteric mechanism of kinase activation; PRD and Bridge domains constitute critical regulatory sites.\",\n      \"method\": \"Cryo-electron microscopy at 3.9 Å resolution\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — near-atomic cryo-EM structure of intact complex revealing allosteric regulatory mechanism\",\n      \"pmids\": [\"29191911\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ZFP161 acts as a scaffolding protein that facilitates interaction between RPA and ATR/ATRIP; ZFP161 binds RPA and ATR/ATRIP through distinct regions and stabilizes the RPA-ATR-ATRIP complex at stalled replication forks, promoting ATR-Chk1 signaling.\",\n      \"method\": \"Co-immunoprecipitation, domain-specific binding assays, ZFP161 knockout mice, ATR/Chk1 signaling assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — co-IP with domain mapping, knockout mouse validation, single lab\",\n      \"pmids\": [\"31757956\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ATRIP directly interacts with MCM2, MCM3, MCM6, and MCM7; downregulation of MCM2 and MCM6 significantly reduces ATRIP chromatin loading; downregulation of MCM2 decreases ATRIP phosphorylation at S224 in a dose-dependent manner.\",\n      \"method\": \"Mass spectrometry, co-immunoprecipitation, GST pulldown, shRNA knockdown, chromatin fractionation\",\n      \"journal\": \"Die Pharmazie\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — GST pulldown and co-IP establish direct interaction, chromatin fractionation shows functional consequence, single lab\",\n      \"pmids\": [\"29442041\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"APE1 directly associates with ssDNA and recruits ATRIP onto ssDNA in an RPA-independent manner; the N-terminal motif of APE1 is required and sufficient for APE1-ATRIP interaction in vitro; this APE1-ATRIP interaction is required for ATRIP recruitment to ssDNA and ATR-Chk1 DDR pathway activation in Xenopus egg extracts; APE1 also directly associates with RPA70 and RPA32 via two distinct motifs.\",\n      \"method\": \"In vitro pulldown, Xenopus egg extract reconstitution, domain mapping with N-terminal APE1 motif mutants, Chk1 phosphorylation assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Weak — in vitro reconstitution with purified proteins and egg extracts, domain mapping, single lab\",\n      \"pmids\": [\"37216274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"REV7 directly binds ATRIP through a defined REV7-interaction motif in ATRIP; mutation of this motif abrogates the REV7-ATRIP interaction in vitro and in cells; REV7 inhibits ATR-mediated phosphorylation of substrates including p53 in vitro; disruption of the REV7-ATRIP interaction enhances CHK1 phosphorylation at Ser317 in cells, establishing REV7 as a negative regulator of ATR signaling.\",\n      \"method\": \"In vitro binding assays, in vitro kinase assays, site-directed mutagenesis of REV7-interaction motif, cellular CHK1 phosphorylation assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro kinase assay, defined interaction motif mutagenesis validated both in vitro and in cells, multiple substrates tested\",\n      \"pmids\": [\"41562258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Cryo-EM structures of human ATR-ATRIP complex at ~3 Å overall resolution in the presence of ATR inhibitors VE-822 and RP-3500 reveal near-complete atomic model including subunit stoichiometry (dimer of heterodimers), intramolecular and intermolecular interactions, and PRD regulatory insertion; one ATR-ATRIP complex binds four VE-822 molecules (two in active site, two at ATR-ATR dimer interface); RP-3500 binding depends on two bound water molecules.\",\n      \"method\": \"Cryo-electron microscopy at ~3 Å resolution with two different inhibitor complexes\",\n      \"journal\": \"Science bulletin\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — near-atomic cryo-EM structures with two inhibitors providing near-complete atomic model and mechanistic insight into inhibition\",\n      \"pmids\": [\"40379520\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ATRIP is the obligate regulatory partner of ATR kinase that forms a dimer-of-heterodimers complex (structurally resolved by cryo-EM); its N-terminal checkpoint recruitment domain (CRD) directly binds RPA-coated ssDNA to recruit ATR-ATRIP to stalled replication forks and DNA damage sites, while its coiled-coil domain mediates ATRIP homo-oligomerization essential for stable ATR binding and checkpoint signaling; a TopBP1-interacting region in ATRIP cooperates with the ATR PRD to enable allosteric kinase activation by TopBP1; ATR-ATRIP activity is further modulated by multiple post-translational modifications (CDK2-dependent S224 phosphorylation, SIRT2-dependent K32 deacetylation, SUMO2/3 modification at K234/K289, and ATR-dependent phosphorylation at S68/S72) and by interacting partners including Nek1 (positive regulator that primes ATR-ATRIP stability and activity), REV7 (negative regulator that inhibits ATR kinase activity by direct ATRIP binding), ZFP161 (scaffolds RPA-ATR-ATRIP assembly), and the FA core complex (enhances ATRIP chromatin loading); through these mechanisms ATRIP coordinates ATR-dependent phosphorylation of Chk1, FANCI, RPA, and other substrates to enforce checkpoint responses to replication stress and DNA damage.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ATRIP is the obligate regulatory partner of the ATR kinase, and the two proteins are mutually dependent for stable expression and for mounting DNA damage checkpoint responses [#0]. ATRIP localizes the complex to sites of genotoxic stress: its N-terminal checkpoint recruitment domain (CRD) directly binds RPA-coated ssDNA, the structure that recruits ATR-ATRIP to DNA damage and stimulates downstream checkpoint kinase activity [#1, #13]. RPA-ssDNA engagement is mediated by multiple, redundant interactions flanking the conserved coiled-coil, which itself drives ATRIP homo-oligomerization required for stable ATR binding and accumulation at lesions; oligomerization per se, rather than the specific coiled-coil sequence, is the essential feature [#9, #12]. Structurally, ATR-ATRIP assembles as a heart-shaped dimer of heterodimers in which an extended HEAT-repeat ATRIP locks the N-termini of two ATR monomers [#22]. Once recruited, the complex is allosterically activated by TopBP1, which engages a dedicated TopBP1-interacting region in ATRIP that cooperates with the ATR PIKK regulatory domain (PRD) to switch on kinase activity, enabling phosphorylation of Chk1 and other substrates [#11, #15]. Distinct ATRIP domains route the complex to distinct outputs: the RPA-binding region supports FANCD2 monoubiquitination and FANCI phosphorylation in the Fanconi anemia pathway, whereas full Chk1 activation requires both the RPA- and TopBP1-binding regions [#16]. ATRIP activity is further tuned by post-translational modifications, including CDK2-cyclin A phosphorylation at S224 controlling G2/M checkpoint maintenance, SIRT2-dependent K32 deacetylation promoting RPA-ssDNA binding, and SUMO2/3 modification at K234/K289 enabling coordinated assembly with ATR, RPA, TopBP1, and MRN [#14, #21, #20], and by interacting partners that act as positive regulators (Nek1, ZFP161) or as a negative regulator (REV7, which directly binds ATRIP to inhibit ATR kinase activity) [#17, #24, #27].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Established that ATR does not function alone but requires a dedicated partner, defining ATRIP as the obligate co-factor of ATR.\",\n      \"evidence\": \"Co-immunoprecipitation, siRNA knockdown, and checkpoint assays in human cells\",\n      \"pmids\": [\"11721054\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define how the complex is recruited to DNA\", \"Did not map interaction surfaces or domains\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified the physical signal that recruits ATR-ATRIP, showing RPA-coated ssDNA as the structure bound by ATRIP to localize the kinase to damage.\",\n      \"evidence\": \"In vitro RPA-ssDNA binding, in vivo recruitment assays, and yeast rfa1-t11 genetics\",\n      \"pmids\": [\"12791985\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not localize the RPA-binding region within ATRIP\", \"Did not establish whether RPA binding is sufficient for kinase activation\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Dissected the biochemistry of ATR-ATRIP DNA binding and activation, showing ATRIP stimulates ssDNA-dependent substrate phosphorylation and that ssDNA/dsDNA junctions plus Claspin promote Chk1 activation.\",\n      \"evidence\": \"In vitro kinase and DNA-binding assays, Xenopus egg extract reconstitution, ATRIP phosphosite mapping (S68/S72)\",\n      \"pmids\": [\"14729973\", \"14724280\", \"15371427\", \"15451423\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RPA-independent low-affinity binding required an unidentified factor\", \"Function of S68/S72 phosphorylation beyond foci accumulation unclear\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Resolved the modular architecture of ATRIP, separating an N-terminal RPA-ssDNA-binding/foci-recruitment function from a coiled-coil oligomerization function required for stable ATR binding.\",\n      \"evidence\": \"Domain deletion and domain-swap mutants, Chk1 phosphorylation, foci and DNA fiber assays in human cells and egg extracts\",\n      \"pmids\": [\"15527801\", \"15743907\", \"16186122\", \"16027118\", \"16176973\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Showed RPA binding is not strictly essential for Chk1 activation, leaving the activation trigger unresolved\", \"Separable replication-fork vs. G2/M functions not mechanistically explained\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined the allosteric activation mechanism, identifying TopBP1 as the direct kinase activator of ATR-ATRIP and mapping multiple redundant RPA-ssDNA contacts in ATRIP.\",\n      \"evidence\": \"In vitro kinase assays with recombinant TopBP1, point mutagenesis, domain mapping of RPA-ssDNA contacts\",\n      \"pmids\": [\"16530042\", \"16407120\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the ATRIP region contacting TopBP1\", \"Did not define the structural basis of activation\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Pinpointed the conserved checkpoint recruitment domain (CRD) mediating RPA binding and a CDK2 phosphosite (S224) regulating the checkpoint, linking ATRIP function to cell-cycle control.\",\n      \"evidence\": \"NMR and mutagenesis of yeast Ddc2 CRD, CDK2-cyclin A kinase assays and S224A checkpoint assays\",\n      \"pmids\": [\"17339343\", \"17638878\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"CRD/RPA disruption only partially compromised checkpoint signaling\", \"TopBP1-mediated activation can bypass RPA binding\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Mapped the ATRIP TopBP1-interacting region and showed it cooperates with the ATR PRD, providing the molecular basis for TopBP1-dependent kinase activation.\",\n      \"evidence\": \"Domain mapping, site-directed mutagenesis of ATR and ATRIP, in vitro kinase and cellular rescue, yeast epistasis\",\n      \"pmids\": [\"18519640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural mechanism of PRD-TopBP1 cooperation not yet resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showed ATRIP domains route signaling to distinct outputs, with the RPA-binding region required for FANCD2/FANCI activation in the Fanconi anemia pathway.\",\n      \"evidence\": \"Conditional ATRIP-deficient DT40 cells, in vitro kinase assays on recombinant FANCI, domain deletion mutants\",\n      \"pmids\": [\"22258451\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How FANCD2 facilitates FANCI phosphorylation mechanistically unclear\", \"Did not address structural basis of domain-specific output\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Expanded the regulatory network of ATRIP, identifying Nek1 and the FA core complex as positive regulators of ATRIP stability and chromatin loading, and BRCA1 BRCT binding to a phospho-ATRIP motif.\",\n      \"evidence\": \"Co-IP, siRNA knockdown, kinase assays, chromatin fractionation in DT40 cells, BRCA1-ATRIP phosphopeptide crystal structure with ITC\",\n      \"pmids\": [\"23345434\", \"23723247\", \"24073851\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional role of BRCA1-ATRIP pS238 binding in vivo not established\", \"FA core complex mechanism distinct from canonical RAD17/TOPBP1 not fully defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Established SUMO2/3 modification of ATRIP as a coordinating switch that promotes simultaneous assembly with multiple partners at damage sites.\",\n      \"evidence\": \"SUMO site mapping (K234/K289), mutants, in vitro SUMO-binding, and SUMO2-fusion rescue\",\n      \"pmids\": [\"24990965\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SUMO ligase responsible for ATRIP modification not identified\", \"Quantitative contribution to checkpoint signaling unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Added acetylation control, showing SIRT2-dependent K32 deacetylation promotes ATRIP recruitment, RPA-ssDNA binding, and replication fork recovery.\",\n      \"evidence\": \"In vitro deacetylation, K32R/K32Q mutants, foci, ATR autophosphorylation, and DNA fiber assays\",\n      \"pmids\": [\"26854234\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Acetyltransferase opposing SIRT2 not identified\", \"How K32 status alters RPA-ssDNA affinity structurally unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided the first structural views of ATR-ATRIP and the orthologous Mec1-Ddc2 as dimers of heterodimers, revealing how ATRIP organizes the complex and how the PRD imposes allosteric kinase regulation.\",\n      \"evidence\": \"Cryo-EM of human ATR-ATRIP (4.7 Å) and yeast Mec1-Ddc2 (3.9 Å); ATRIP-MCM interaction mapping by MS/pulldown\",\n      \"pmids\": [\"29271416\", \"29191911\", \"29442041\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Limited resolution of human structure left ATRIP details incomplete\", \"Functional significance of ATRIP-MCM interaction only partially defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified ZFP161 as a scaffold that stabilizes the RPA-ATR-ATRIP assembly at stalled forks, extending the list of positive recruitment factors.\",\n      \"evidence\": \"Co-IP, domain mapping, ZFP161 knockout mice, ATR-Chk1 signaling assays\",\n      \"pmids\": [\"31757956\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; structural basis of scaffolding undefined\", \"Generality across damage types not established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed an RPA-independent recruitment route, with APE1 directly recruiting ATRIP to ssDNA to activate the ATR-Chk1 pathway.\",\n      \"evidence\": \"In vitro pulldown, Xenopus egg extract reconstitution, APE1 N-terminal motif mutagenesis, Chk1 phosphorylation\",\n      \"pmids\": [\"37216274\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; in vivo importance in human cells not established\", \"Relationship to canonical RPA-dependent recruitment unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified REV7 as a direct negative regulator binding a defined ATRIP motif to inhibit ATR kinase activity, and produced near-atomic inhibitor-bound structures of the complex.\",\n      \"evidence\": \"In vitro binding and kinase assays, REV7-interaction motif mutagenesis, cellular CHK1 assays; cryo-EM at ~3 Å with VE-822 and RP-3500\",\n      \"pmids\": [\"41562258\", \"40379520\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular conditions governing REV7-mediated inhibition not fully defined\", \"How inhibitor binding relates to physiological activation states partially resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple ATRIP recruitment routes (RPA-dependent, APE1-dependent, FA-complex-dependent) and the layered PTMs and partner interactions are integrated to set ATR activity thresholds in vivo remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified quantitative model of recruitment vs. activation\", \"Spatiotemporal hierarchy of PTMs and partner binding not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [1, 3, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 9, 15]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 11, 27]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4, 6, 7]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [1, 18]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 1, 16]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [5, 14]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [5, 11, 17]}\n    ],\n    \"complexes\": [\"ATR-ATRIP\"],\n    \"partners\": [\"ATR\", \"RPA70\", \"TOPBP1\", \"NEK1\", \"REV7\", \"ZFP161\", \"BRCA1\", \"MCM2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}