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].
| Year | Confidence | Finding | PMIDs | Journal |
|---|---|---|---|---|
| 2001 | High | 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. | PMID:11721054 | Science |
| 2003 | High | 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. | PMID:12791985 | Science |
| 2004 | Medium | 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. | PMID:14729973 | Molecular and cellular biology |
| 2004 | Medium | 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. | PMID:14724280 | The Journal of biological chemistry |
| 2004 | Medium | 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. | PMID:15451423 | Biochemical and biophysical research communications |
| 2004 | High | 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. | PMID:15371427 | The Journal of biological chemistry |
| 2004 | Medium | 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. | PMID:15527801 | FEBS letters |
| 2005 | High | 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. | PMID:15743907 | Molecular biology of the cell |
| 2005 | High | 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. | PMID:16186122 | The Journal of biological chemistry |
| 2005 | High | 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. | PMID:16027118 | The Journal of biological chemistry |
| 2005 | Medium | 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. | PMID:16176973 | Molecular biology of the cell |
| 2006 | High | 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. | PMID:16530042 | Cell |
| 2006 | Medium | 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. | PMID:16407120 | Proceedings of the National Academy of Sciences of the United States of America |
| 2007 | High | 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. | PMID:17339343 | Molecular and cellular biology |
| 2007 | High | 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. | PMID:17638878 | Cancer research |
| 2008 | High | 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. | PMID:18519640 | Genes & development |
| 2012 | High | 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. | PMID:22258451 | Cancer research |
| 2013 | High | 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. | PMID:23345434 | Proceedings of the National Academy of Sciences of the United States of America |
| 2013 | Medium | 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. | PMID:23723247 | Nucleic acids research |
| 2013 | High | 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. | PMID:24073851 | Biochemistry |
| 2014 | High | 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. | PMID:24990965 | Genes & development |
| 2016 | High | 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. | PMID:26854234 | Cell reports |
| 2017 | High | 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. | PMID:29271416 | Cell research |
| 2017 | High | 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. | PMID:29191911 | Science |
| 2019 | Medium | 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. | PMID:31757956 | Nature communications |
| 2017 | Medium | 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. | PMID:29442041 | Die Pharmazie |
| 2023 | Medium | 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. | PMID:37216274 | eLife |
| 2025 | High | 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. | PMID:41562258 | Nucleic acids research |
| 2025 | High | 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. | PMID:40379520 | Science bulletin |