GO:0070310 ATR-ATRIP complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070310 (ATR-ATRIP complex) is a cellular_component defined as a protein complex containing the protein kinase ATR and ATR-interacting protein (ATRIP) that binds single-stranded DNA, with increased ssDNA affinity in the presence of replication protein A.
• Cryo-EM structures of human ATR-ATRIP reveal a dimeric architecture in which ATRIP mediates DNA binding and ATR provides the kinase domain for checkpoint signaling.
• ATRIP oligomerization is required for ATR-dependent checkpoint signaling, making the complex a functional unit rather than a simple enzyme-cofactor pair.
• The complex is activated by TOPBP1, which stimulates ATR kinase activity at sites of replication stress and DNA damage.
• ATR-ATRIP is recruited to replication forks and DNA cross-link repair sites through interactions with proteins such as ZFP161 and the Fanconi anemia core complex.
• Dysregulation of ATR-ATRIP signaling is linked to cancer, replication stress disorders, and chemoresistance, making it a major target for CRISPR-based functional studies.
Description
The ATR-ATRIP complex (GO:0070310) is a cellular_component that sits at the heart of the DNA damage response, coordinating cell cycle checkpoints and replication fork stabilization. It consists of the protein kinase ATR (ataxia telangiectasia and Rad3-related) and its obligate partner ATRIP (ATR-interacting protein), and it binds single-stranded DNA (ssDNA) with increased affinity when replication protein A (RPA) is present. This complex is essential for detecting stalled replication forks and DNA lesions that generate ssDNA, and for transmitting signals that halt cell cycle progression until damage is repaired. For researchers, GO:0070310 is a focal point because it connects structural biology, DNA repair, and cancer therapeutics. Cryo-EM studies have resolved the human ATR-ATRIP architecture, showing how ATRIP anchors the complex to DNA and how ATR is positioned for substrate phosphorylation. The complex is also a target of regulatory inputs, including TOPBP1, which directly stimulates ATR kinase activity. Understanding its composition, assembly, and regulation is therefore critical for interpreting genome stability phenotypes and for designing CRISPR screens that probe checkpoint biology. This article synthesizes authoritative QuickGO annotation and verified PubMed literature to provide a research-grade overview of the ATR-ATRIP complex. It covers the definition, structural components, molecular mechanism, key genes, disease links, and experimental methods, with a focus on how CRISPR-based models can be used to interrogate this complex in human cells.
ATR-ATRIP complex At A Glance
| GO ID | GO:0070310 |
|---|---|
| GO term | ATR-ATRIP complex |
| Ontology | cellular_component |
| Synonym | Mec1-Lcd1 complex, Rad3-Rad26 complex |
| Major function | Binds single-stranded DNA and mediates ATR-dependent checkpoint signaling; ssDNA binding is enhanced by replication protein A |
| Key subunits | ATR (protein kinase) and ATRIP (ATR-interacting protein) |
| Structural feature | Dimeric assembly with ATRIP mediating DNA binding and ATR providing the kinase domain |
| Regulatory activator | TOPBP1 stimulates ATR kinase activity within the complex |
| Functional requirement | ATRIP oligomerization is required for ATR-dependent checkpoint signaling |
What Is GO:0070310?
According to the Gene Ontology, GO:0070310 (ATR-ATRIP complex) is a protein complex that contains the protein kinase ATR and ATR-interacting protein (ATRIP) and binds single-stranded DNA; ssDNA binding affinity is increased in the presence of replication protein A. In other words, it is a DNA damage-sensing module in which ATRIP provides a platform for ssDNA recognition and ATR delivers serine/threonine kinase activity to downstream checkpoint effectors.
Why Is ATR-ATRIP complex Important in Cell Biology?
The ATR-ATRIP complex is a central node in the DNA damage response and is essential for maintaining genome stability during replication. Because it detects ssDNA generated at stalled forks and resects damaged DNA, its activity determines whether cells arrest, repair, or undergo apoptosis. Its dysfunction or hyperactivation is implicated in cancer, chemoresistance, and replication stress syndromes, and it is a major target for small-molecule inhibitors and CRISPR-based functional genomics.
• It is the primary sensor of single-stranded DNA at stalled replication forks and resected DNA breaks.
• It activates the replication checkpoint through ATR-mediated phosphorylation of downstream effectors.
• ATRIP oligomerization is required for ATR-dependent checkpoint signaling, defining the complex as a cooperative unit.
• TOPBP1 directly stimulates ATR-ATRIP kinase activity, linking the complex to a broader DNA damage response network.
• It participates in DNA cross-link repair through interplay with the Fanconi anemia core complex.
• ZFP161 recruits the ATR/ATRIP complex to regulate replication fork stability and genomic stability.
• Its structural architecture has been resolved by cryo-EM, enabling structure-guided inhibitor design.
• It is a therapeutic target in cancers with replication stress and homologous recombination defects.
• It is widely studied using CRISPR knockout and knock-in models to dissect checkpoint function.
• Its dysfunction is linked to genomic instability and sensitivity to DNA-damaging agents.
What Happens During ATR-ATRIP complex?
Recognition of single-stranded DNA
In simple terms: The complex first finds and grabs single-stranded DNA that appears when replication stalls or DNA is damaged.
The ATR-ATRIP complex binds single-stranded DNA (ssDNA) generated at stalled replication forks or resected DNA lesions. This binding is mediated by ATRIP and is enhanced by replication protein A (RPA), which coats ssDNA and increases the affinity of the complex for DNA. The complex therefore acts as a sensor that localizes to regions of exposed ssDNA.
Assembly and oligomerization
In simple terms: ATR and ATRIP come together, and ATRIP molecules cluster to form a functional signaling unit.
ATRIP oligomerization is required for ATR-dependent checkpoint signaling, indicating that the complex must assemble into higher-order structures to function. Structural studies show that human ATR-ATRIP forms a dimeric assembly in which ATRIP provides the DNA-binding interface and ATR contributes the kinase domain. This architecture positions ATR for phosphorylation of downstream substrates.
Activation by TOPBP1
In simple terms: A helper protein called TOPBP1 switches on the ATR kinase so it can send damage signals.
TOPBP1 activates the ATR-ATRIP complex by directly stimulating ATR kinase activity. Recent structural work has revealed the molecular mechanism by which TOPBP1 engages ATR-ATRIP to promote checkpoint kinase activation. This activation step is critical for amplifying the DNA damage signal and for triggering cell cycle arrest.
Downstream checkpoint signaling
In simple terms: Once active, the complex phosphorylates other proteins that stop the cell cycle and promote repair.
Activated ATR within the ATR-ATRIP complex phosphorylates downstream effectors such as CHK1, leading to cell cycle arrest and inhibition of origin firing. The complex also interacts with proteins involved in DNA cross-link repair, including the Fanconi anemia core complex, to coordinate repair processes. Through these signaling events, the complex maintains replication fork stability and genomic integrity.
Key Genes Involved in GO:0070310 ATR-ATRIP complex
The following genes and proteins are central to the composition, regulation, and function of the ATR-ATRIP complex (GO:0070310).
| Gene | Major Role | Research Relevance |
|---|---|---|
| ATR | Protein kinase subunit of the complex; phosphorylates downstream checkpoint effectors | Core catalytic component; target for kinase inhibitors and CRISPR knockout studies |
| ATRIP | ATR-interacting protein; mediates ssDNA binding and oligomerization | Essential for complex assembly and DNA binding; required for checkpoint signaling |
| TOPBP1 | Activator of ATR-ATRIP kinase activity | Stimulates ATR kinase; structural basis of activation recently resolved |
| RPA1 | Replication protein A subunit; coats ssDNA and enhances ATR-ATRIP binding | Modulates ssDNA binding affinity of the complex |
| RPA2 | Replication protein A subunit; part of the ssDNA-binding heterotrimer | Contributes to RPA-ssDNA nucleoprotein filament that recruits ATR-ATRIP |
| RPA3 | Replication protein A subunit; completes the RPA heterotrimer | Supports RPA function in ATR-ATRIP recruitment |
| ZFP161 | Recruits ATR/ATRIP to replication forks | Regulates fork stability and genomic stability |
| FANCA | Fanconi anemia core complex component; interacts with ATR-ATRIP | Links ATR-ATRIP to DNA cross-link repair |
| FANCC | Fanconi anemia core complex component | Interplay with ATR-ATRIP during cross-link repair |
| FANCG | Fanconi anemia core complex component | Interplay with ATR-ATRIP during cross-link repair |
| CHK1 | Downstream effector kinase phosphorylated by ATR | Mediates checkpoint arrest; readout of ATR-ATRIP activity |
| CDC25A | Phosphatase targeted by CHK1 to enforce cell cycle arrest | Downstream target of ATR-ATRIP signaling |
| MEC1 | Yeast ortholog of ATR | Model organism studies of checkpoint signaling |
| LCD1 | Yeast ortholog of ATRIP | Model organism studies of complex assembly |
| RAD3 | Fission yeast ortholog of ATR | Model organism studies of DNA damage response |
| RAD26 | Fission yeast ortholog of ATRIP | Model organism studies of complex assembly |
| H2AX | Histone variant phosphorylated at damage sites; facilitates ATR-ATRIP recruitment | Marker of DNA damage response and ATR-ATRIP activation |
How Is ATR-ATRIP complex Regulated?
The ATR-ATRIP complex is regulated at multiple levels. Its recruitment to ssDNA is enhanced by RPA, which increases the complex's DNA binding affinity. ATRIP oligomerization is required for ATR-dependent checkpoint signaling, providing a mode of regulation through complex assembly. The kinase activity of ATR is stimulated by TOPBP1, which directly engages the complex and promotes activation. Additionally, proteins such as ZFP161 recruit the complex to replication forks to maintain fork stability, and the Fanconi anemia core complex modulates ATR-ATRIP function during DNA cross-link repair. These regulatory inputs ensure that ATR-ATRIP signaling is spatially and temporally controlled.
ATR-ATRIP complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ATR | Cancer, replication stress, chemoresistance | CRISPR knockout in cancer cell lines; point mutation of kinase domain |
| ATRIP | Genomic instability, checkpoint defects | Knockout and oligomerization-deficient knock-in models |
| TOPBP1 | Cancer, DNA damage response defects | Knockout and activation-domain point mutants |
| ZFP161 | Replication fork instability, genomic instability | Knockout and tagged knock-in for localization studies |
| FANCA | Fanconi anemia, cross-link repair deficiency | Knockout in patient-derived cells; complementation with wild-type |
Cancer and replication stress
ATR-ATRIP signaling is frequently upregulated in cancers that experience high replication stress, allowing tumor cells to survive DNA damage and resist chemotherapy. Inhibitors of ATR kinase are being developed as anticancer agents, and the structural details of the human ATR-ATRIP complex have accelerated structure-guided drug design. Loss of ATR-ATRIP function sensitizes cells to DNA-damaging agents, making the complex a target for synthetic lethality approaches.
Fanconi anemia and cross-link repair disorders
The ATR-ATRIP complex interacts with the Fanconi anemia core complex during DNA cross-link repair, and disruption of this interplay can lead to genomic instability characteristic of Fanconi anemia. This connection highlights the complex's role in repairing interstrand cross-links and maintaining chromosomal integrity.
Genomic instability syndromes
Defects in ATR-ATRIP signaling components, including ATRIP oligomerization, impair checkpoint responses and lead to genomic instability. ZFP161-mediated recruitment of ATR/ATRIP is also required for replication fork stability, and its loss compromises genomic stability. These findings link the complex to disorders characterized by replication stress and chromosome fragility.
From ATR-ATRIP complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ATR-ATRIP function impair checkpoint signaling? | CRISPR knockout of ATR or ATRIP in human cell lines |
| How does a specific ATR mutation affect kinase activity? | Point mutation knock-in of ATR catalytic residues |
| Where does ATR-ATRIP localize after DNA damage? | Endogenous tagged knock-in of ATRIP or ATR with fluorescent tags |
| Does overexpression of ATRIP enhance checkpoint signaling? | Overexpression of wild-type or mutant ATRIP |
| What genes modify sensitivity to ATR-ATRIP inhibition? | CRISPR library screening with ATR inhibitors |
| How does TOPBP1 activate ATR-ATRIP structurally? | Knock-in of TOPBP1 activation domain mutants combined with structural assays |
How to Study the ATR-ATRIP complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Cryo-EM | Three-dimensional structure of the ATR-ATRIP complex | Determining subunit arrangement and DNA-binding interface |
| Electrophoretic mobility shift assay | DNA binding affinity of the complex | Testing effects of ATRIP mutations and RPA on ssDNA binding |
| In vitro kinase assay | ATR kinase activity toward substrates | Measuring activation by TOPBP1 and inhibition by small molecules |
| Immunoblotting for phospho-CHK1 | Downstream checkpoint activation | Assessing ATR-ATRIP function after DNA damage |
| Cell cycle analysis | Cell cycle arrest and progression | Evaluating checkpoint defects in knockout cells |
| CRISPR knockout screening | Gene dependencies and modifiers of ATR-ATRIP inhibition | Identifying synthetic lethal targets |
| Fluorescence microscopy | Subcellular localization of ATR-ATRIP | Tracking recruitment to replication forks and damage sites |
| Co-immunoprecipitation | Protein-protein interactions | Mapping complex components and interacting partners |
Structural biology (cryo-EM and crystallography)
Cryo-EM has been used to determine the architecture of the human ATR-ATRIP complex, revealing a dimeric assembly and the DNA-binding interface. These methods provide atomic-level insights into how ATRIP engages ssDNA and how ATR is positioned for catalysis. Structural studies also inform the design of inhibitors that target the complex.
Biochemical assays for DNA binding and kinase activity
DNA binding of the ATR-ATRIP complex can be measured using electrophoretic mobility shift assays, and kinase activity can be assessed with in vitro phosphorylation assays using downstream substrates such as CHK1. These assays are used to test the effects of mutations in ATR, ATRIP, or regulatory proteins like TOPBP1.
Cell-based checkpoint assays
Checkpoint signaling can be monitored by immunoblotting for phosphorylated CHK1 or other ATR substrates after DNA damage or replication stress. Cell cycle analysis and viability assays further reveal the functional consequences of ATR-ATRIP loss or inhibition.
Genome-wide CRISPR screening
CRISPR knockout library screening can identify genes that modify sensitivity to ATR-ATRIP inhibition or that regulate checkpoint signaling. Such screens are powerful for uncovering synthetic lethal interactions and resistance mechanisms involving the complex.
How CRISPR Can Be Used to Study GO:0070310 ATR-ATRIP complex
Knockout
CRISPR knockout of ATR or ATRIP is used to abolish ATR-ATRIP complex function and assess its role in checkpoint signaling, replication fork stability, and sensitivity to DNA-damaging agents. Knockout cell lines are valuable for validating dependency on the complex and for identifying compensatory pathways.
Point Mutation
Point mutation knock-in can be used to dissect specific residues required for ATR kinase activity, ATRIP oligomerization, or DNA binding. For example, mutations that disrupt ATRIP oligomerization can be introduced to test the requirement for complex assembly in checkpoint signaling.
Knock-in
Knock-in of epitope tags or fluorescent proteins at the endogenous ATR or ATRIP loci enables real-time imaging and biochemical purification of the complex. Tagged knock-in models are also useful for studying the recruitment of ATR-ATRIP to replication forks and DNA damage sites.
Overexpression
Overexpression of wild-type or mutant ATR, ATRIP, or TOPBP1 can be used to test gain-of-function effects on checkpoint signaling and DNA repair. Overexpression models help determine whether increased complex activity promotes chemoresistance or alters replication fork dynamics.
How EDITGENE Supports ATR-ATRIP complex Research
Researchers studying ATR-ATRIP complex-related genes often need to determine whether a candidate gene is causally involved in checkpoint signaling, replication fork stability, or drug sensitivity. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models that answer these questions.
Contact EDITGENE today to design your custom CRISPR model for ATR-ATRIP complex research.
Frequently Asked Questions About ATR-ATRIP complex
What is the ATR-ATRIP complex?
The ATR-ATRIP complex (GO:0070310) is a protein complex containing the kinase ATR and ATR-interacting protein (ATRIP) that binds single-stranded DNA; its ssDNA binding affinity is increased by replication protein A.
What genes are involved in the ATR-ATRIP complex?
The core genes are ATR and ATRIP, with regulatory proteins including TOPBP1, RPA subunits, ZFP161, and Fanconi anemia core complex components.
What is the function of GO:0070310?
GO:0070310 functions as a DNA damage sensor that binds single-stranded DNA and activates ATR-dependent checkpoint signaling to maintain genome stability.
How is the ATR-ATRIP complex activated?
It is activated by TOPBP1, which directly stimulates ATR kinase activity, and by ATRIP oligomerization, which is required for checkpoint signaling.
What diseases are associated with ATR-ATRIP dysfunction?
Dysregulation is linked to cancer, replication stress, chemoresistance, Fanconi anemia, and genomic instability syndromes.
What is the structure of the human ATR-ATRIP complex?
Cryo-EM studies show a dimeric assembly in which ATRIP mediates DNA binding and ATR provides the kinase domain.
How can I study the ATR-ATRIP complex using CRISPR?
CRISPR knockout, point mutation knock-in, tagged knock-in, and overexpression models can be used to dissect its function and regulation.
What methods are used to measure ATR-ATRIP activity?
Common methods include cryo-EM, DNA binding assays, in vitro kinase assays, phospho-CHK1 immunoblotting, and cell cycle analysis.
Why is the ATR-ATRIP complex a cancer drug target?
Because it allows cancer cells to survive replication stress and resist DNA-damaging therapies, making its inhibition a promising therapeutic strategy.
What are the synonyms for GO:0070310?
The synonyms are Mec1-Lcd1 complex and Rad3-Rad26 complex, reflecting yeast orthologs.
Conclusion
The ATR-ATRIP complex (GO:0070310) is a central DNA damage sensor and checkpoint activator composed of the ATR kinase and its partner ATRIP. Its ability to bind single-stranded DNA, assemble into oligomers, and be activated by TOPBP1 makes it essential for replication fork stability and genome maintenance. Structural and functional studies have illuminated its architecture and regulatory mechanisms, providing a foundation for therapeutic targeting in cancer and genomic instability disorders. CRISPR-based models, including knockout, point mutation, knock-in, and overexpression cell lines, are powerful tools for dissecting ATR-ATRIP biology and for identifying synthetic lethal interactions. EDITGENE offers end-to-end services to generate these models and support researchers in advancing ATR-ATRIP-focused discoveries.
References
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- 3. Kumagai A et al.. 2006. TopBP1 activates the ATR-ATRIP complex.. Cell 124(5):943-55 PMID: 16530042
- 4. Bomgarden RD et al.. 2004. A novel protein activity mediates DNA binding of an ATR-ATRIP complex.. J Biol Chem 279(14):13346-53 PMID: 14724280
- 5. Li B et al.. 2026. Structural mechanism of TOPBP1 activating the ATR-ATRIP replication checkpoint kinase.. Nat Struct Mol Biol 33(8):1204-1213 PMID: 42493622
- 6. Kim W et al.. 2019. ZFP161 regulates replication fork stability and maintenance of genomic stability by recruiting the ATR/ATRIP complex.. Nat Commun 10(1):5304 PMID: 31757956
- 7. Tomida J et al.. 2013. A novel interplay between the Fanconi anemia core complex and ATR-ATRIP kinase during DNA cross-link repair.. Nucleic Acids Res 41(14):6930-41 PMID: 23723247
- 8. Ball HL et al.. 2005. ATRIP oligomerization is required for ATR-dependent checkpoint signaling.. J Biol Chem 280(36):31390-6 PMID: 16027118
