Affinage

FANCI

Fanconi anemia group I protein · UniProt Q9NVI1

Length
1328 aa
Mass
149.3 kDa
Annotated
2026-04-28
79 papers in source corpus 44 papers cited in narrative 43 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

FANCI is a central component of the Fanconi anemia (FA) DNA repair pathway that forms a heterodimeric sliding clamp with FANCD2 (the ID2 complex), which diffuses along dsDNA and stalls at ssDNA–dsDNA junctions at stalled replication forks to coordinate interstrand crosslink (ICL) repair, replication fork protection, and cell fate decisions (PMID:39085614, PMID:17412408). ATR-mediated phosphorylation of FANCI at S556/S559/S565 destabilizes the open ID2 conformation and primes the complex for monoubiquitination by the FA core complex (UBE2T–FANCL), whereupon ubiquitin acts as a covalent molecular pin that locks the closed clamp around dsDNA; FANCI monoubiquitination at K523 in turn shields FANCD2-ubiquitin from USP1-mediated deubiquitination, sustaining pathway activation (PMID:36050501, PMID:32510829, PMID:36385258, PMID:32117957). The activated ID2 clamp recruits FAN1 nuclease for ICL unhooking, stabilizes RAD51–DNA filaments to protect stalled forks, and—when repair fails—FANCI switches from FANCD2 to PIDD1, triggering PIDDosome-mediated apoptosis (PMID:20671156, PMID:27694619, PMID:34256011). Biallelic loss-of-function mutations in FANCI cause Fanconi anemia complementation group I, and FANCI also functions independently of FANCD2 in ribosome biogenesis and regulation of dormant replication origin firing (PMID:17460694, PMID:30692263, PMID:25843623).

Mechanistic history

Synthesis pass · year-by-year structured walk · 15 steps
  1. 2007 High

    The identification of FANCI as a monoubiquitinated binding partner of FANCD2 established the ID heterodimer as the central effector of the FA pathway and linked biallelic FANCI mutations to Fanconi anemia complementation group I.

    Evidence Co-IP, chromatin fractionation, complementation, and patient mutation analysis in human cells

    PMID:17412408 PMID:17460694

    Open questions at the time
    • Ubiquitination site on FANCI not yet mapped
    • Mechanism of mutual ubiquitin dependence unknown
    • DNA substrate specificity not determined
  2. 2008 High

    ATR-mediated phosphorylation of FANCI SQ/TQ motifs was shown to act as a molecular switch that activates FANCD2 monoubiquitination and focus formation, establishing the signaling hierarchy upstream of ID2 activation.

    Evidence Phosphomimetic and phosphodead FANCI mutants in DT40 and human cells with survival, breakage, and ubiquitination assays

    PMID:18931676

    Open questions at the time
    • Specific phosphorylated residues not individually resolved
    • Direct kinase–substrate relationship not reconstituted in vitro at this point
  3. 2009 High

    Biochemical reconstitution demonstrated that FANCI binds DNA (preferring branched structures), is monoubiquitinated at K523 by UBE2T–FANCL, and restricts FANCD2 ubiquitination to the correct lysine, revealing FANCI as both a DNA sensor and a substrate-specificity determinant for the FA E3 ligase.

    Evidence In vitro ubiquitination with purified UBE2T, FANCL, FANCI; DNA binding assays with truncations and point mutants

    PMID:19111657 PMID:19561358 PMID:19589784

    Open questions at the time
    • DNA-stimulated ubiquitination not yet demonstrated
    • Structural basis of DNA recognition unknown
  4. 2010 High

    The monoubiquitinated ID2 complex was found to recruit FAN1 nuclease to ICL sites, providing the first downstream effector mechanism for ubiquitin-activated ID2, while patient-derived FANCI C-terminal mutations revealed separable NLS and DNA-repair elements.

    Evidence Reciprocal Co-IP, chromatin fractionation, siRNA, ICL sensitivity assays; patient mutant localization and complementation

    PMID:20671156 PMID:20971953

    Open questions at the time
    • Mechanism of FAN1 recognition of ubiquitin on ID2 not structurally resolved
    • Other downstream effectors not identified
  5. 2011 High

    The 3.4 Å crystal structure of the ID2 complex revealed that ubiquitination and phosphorylation sites map to the heterodimer interface, explaining how these modifications regulate complex opening/closing and DNA engagement.

    Evidence X-ray crystallography of the ~300 kDa ID2 complex with DNA binding assays

    PMID:21764741

    Open questions at the time
    • Structure was of the unmodified complex; ubiquitinated conformation unknown
    • Mechanism of conformational change upon modification not resolved
  6. 2012 High

    DNA was shown to robustly stimulate FANCD2 monoubiquitination in a manner strictly requiring FANCI DNA-binding activity, directly coupling FANCI's role as a DNA sensor to enzymatic activation of the pathway.

    Evidence In vitro reconstituted ubiquitination with various DNA substrates and FANCI DNA-binding mutants

    PMID:22287633 PMID:24623813

    Open questions at the time
    • R-loop and RNA substrates not yet tested
    • Contribution of individual FANCI DNA-binding residues not mapped
  7. 2015 High

    FANCI was found to regulate dormant replication origin firing via ATR-dependent phosphorylation and to co-localize with MCM-bound chromatin, revealing a replication-regulatory function distinct from ICL repair.

    Evidence Super-resolution microscopy, DNA fiber assays, phosphomimetic/phosphodead mutants, siRNA

    PMID:25843623

    Open questions at the time
    • Mechanism of FANCI-MCM interaction not biochemically defined
    • Whether this function requires FANCD2 not fully resolved
  8. 2016 High

    Cryo-EM of the ID2 complex revealed an inner cavity accommodating dsDNA, the homodimeric FANCB–FANCL–FAAP100 catalytic module of the FA core complex was structurally defined, and FANCI was shown to stabilize RAD51–DNA filaments for fork protection, broadening the effector repertoire of the activated ID2 clamp.

    Evidence Cryo-EM, XL-MS, biochemical reconstitution, in vitro RAD51 filament stabilization with FANCI DNA-binding mutants

    PMID:27405460 PMID:27694619 PMID:27986592

    Open questions at the time
    • Full reconstitution of ICL repair with ubiquitinated ID2 not achieved
    • Structural basis of RAD51–ID2 interaction unknown
  9. 2017 High

    Two-wave phosphorylation of FANCI S556/S559/S565 was resolved: S556 phosphorylation is ubiquitination-independent and acts upstream, while S559/S565 phosphorylation is ubiquitination-linked and inhibits USP1-mediated deubiquitination, establishing a feed-forward activation loop.

    Evidence Phospho-specific antibodies, ubiquitination-resistant and phosphomimetic mutants, USP1 depletion, ICL repair assays

    PMID:28636932

    Open questions at the time
    • Structural basis of how phosphorylation blocks USP1 access not resolved
    • Kinase responsible for ubiquitination-linked wave not confirmed in vitro
  10. 2019 Medium

    FANCI was localized to the nucleolus where it functions in ribosome biogenesis (pre-rRNA processing) independently of FANCD2, maintained in a deubiquitinated state by USP1 and USP36, revealing a non-canonical FANCI function.

    Evidence Immunofluorescence, siRNA knockdown, pre-rRNA processing assays, immunoprecipitation

    PMID:30692263

    Open questions at the time
    • Direct rRNA-binding activity of FANCI not demonstrated
    • Mechanism of FANCI involvement in rRNA processing unknown
    • Independence from FANCD2 tested by knockdown only
  11. 2019 High

    The ID2 complex was found to bind ssRNA and R-loop substrates with high affinity and these substrates stimulate monoubiquitination, expanding the range of nucleic acid structures sensed by FANCI beyond dsDNA and branched DNA.

    Evidence In vitro binding and ubiquitination assays with purified ID2 and synthetic R-loop/RNA substrates; DART assay for in-cell R-loop colocalization

    PMID:30650351

    Open questions at the time
    • In vivo significance of R-loop sensing for ICL repair not established
    • Whether R-loop binding triggers the same downstream effectors as dsDNA binding is unclear
  12. 2020 High

    Cryo-EM structures of ubiquitinated ID2 revealed that FANCD2 monoubiquitination drives a closed conformation that encircles dsDNA, with ubiquitin serving as a molecular pin at the heterodimer interface; FANCI ubiquitination protects FANCD2-ubiquitin from USP1, and ATR phosphorylation of FANCI was reconstituted in vitro to show it stabilizes DNA association and stimulates ubiquitination.

    Evidence Cryo-EM of chicken and human ubiquitinated ID2 complexes, in vitro reconstitution with recombinant ATR, deubiquitination assays with USP1-UAF1, ubiquitin mutant analysis

    PMID:32066963 PMID:32117957 PMID:32167469 PMID:32510829

    Open questions at the time
    • Sequential order of FANCD2 vs FANCI ubiquitination not structurally resolved in one reaction
    • Filament-like arrays on dsDNA not functionally characterized
  13. 2021 High

    FANCI was shown to interact with PIDD1, enabling PIDDosome assembly and caspase-2-mediated apoptosis when ICL repair fails; monoubiquitination at K523 acts as a switch between FANCD2 (repair) and PIDD1 (apoptosis), establishing FANCI as a cell-fate decision node.

    Evidence Reciprocal Co-IP, FANCI KO, caspase-2 activity assays, K523R mutagenesis, epistasis with nuclease deletions

    PMID:34256011

    Open questions at the time
    • Structural basis of FANCI–PIDD1 interaction unknown
    • Whether this switch operates in vivo during physiological ICL exposure not demonstrated
  14. 2022 High

    Cryo-EM structures of phosphomimetic FANCI in the ID2 complex demonstrated that phosphorylation destabilizes the open state and promotes complex closure around DNA independently of the FA core complex, while structures of FANCI-ubiquitinated complexes showed that FANCI-Ub maintains FANCD2 K561 exposed for re-ubiquitination, completing the structural description of the activation cascade.

    Evidence Cryo-EM of phosphomimetic and mono-ubiquitinated ID2 species, in vitro ubiquitination/deubiquitination assays

    PMID:36050501 PMID:36385258

    Open questions at the time
    • Full pathway reconstitution from phosphorylation through ubiquitination to ICL unhooking not achieved in one system
    • Dynamics of re-ubiquitination cycle in vivo unknown
  15. 2024 High

    Single-molecule imaging revealed that the ID2 complex is a sliding clamp that diffuses on dsDNA and stalls specifically at ssDNA–dsDNA junctions, providing a unified mechanism for replication fork recognition; separately, PP2A was identified as the phosphatase that dephosphorylates inhibitory FANCD2 sites to license ID2 chromatin loading.

    Evidence Single-molecule TIRF imaging, cryo-EM of junction-stalled ID2, in vitro PP2A-coupled ubiquitination reconstitution, super-resolution live-cell tracking

    PMID:39085614 PMID:39535917

    Open questions at the time
    • Sliding and stalling behavior not yet observed in living cells
    • How PP2A is itself regulated at ICL sites is unknown
    • Whether sliding occurs on nucleosomal DNA not tested

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include: how FANCI participates in ribosome biogenesis at the molecular level, the structural basis of the FANCI–PIDD1 apoptotic switch, and whether the sliding-clamp and junction-stalling mechanism operates on chromatinized templates in vivo.
  • No reconstitution of FANCI function in rRNA processing
  • No structure of FANCI–PIDD1 complex
  • Sliding/stalling not demonstrated on chromatin in vivo

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003677 DNA binding 6 GO:0060090 molecular adaptor activity 3 GO:0003723 RNA binding 1
Localization
GO:0005634 nucleus 3 GO:0005694 chromosome 3 GO:0005730 nucleolus 1
Pathway
R-HSA-73894 DNA Repair 9 R-HSA-69306 DNA Replication 2 R-HSA-1643685 Disease 1 R-HSA-5357801 Programmed Cell Death 1
Partners
FAN1FANCD2FANCLPIDD1RAD51SF3B1UBE2TUSP1
Complex memberships
FANCI-FANCD2 (ID2) complex

Evidence

Reading pass · 43 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 FANCI is monoubiquitinated on a specific lysine residue and forms a heterodimeric complex with FANCD2 (the ID complex) that localizes to chromatin in response to DNA damage. Ubiquitination of each protein is required for maintenance of ubiquitin on the other, indicating a dual ubiquitin-locking mechanism. Co-immunoprecipitation, Western blot, chromatin fractionation, cell-based complementation assays Cell High 17412408
2007 FANCI is a second monoubiquitinated component of the FA pathway; biallelic mutations in FANCI cause Fanconi anemia complementation group I. Sequence homology search, mutation analysis, biochemical validation Nature structural & molecular biology High 17460694
2008 ATR/ATM-mediated phosphorylation of multiple conserved Ser/Thr-Gln (SQ/TQ) motifs on FANCI serves as a molecular switch to activate the FA pathway, promoting monoubiquitination of both FANCI and FANCD2 and their focus formation. Phosphomimetic FANCI constitutively activates the pathway; phosphodead FANCI abrogates it. Alanine/phosphomimetic substitution mutagenesis in chicken DT40 cells, immunofluorescence, survival assays, chromosome breakage assays Nature structural & molecular biology High 18931676
2008 FANCI protein enhances monoubiquitination of FANCD2 by the Ube2t-FANCL pair and restricts ubiquitination to the correct in vivo substrate lysine residue on FANCD2, establishing FANCI's role in site-restricted monoubiquitination. In vitro reconstitution of monoubiquitination with purified Ube2t, FANCL, and FANCI; mutational analysis Molecular cell High 19111657
2009 FANCI directly binds DNA with preference for branched structures; the DNA binding domain encompasses residues 200–1000. FANCI is monoubiquitinated on Lys-523 by the UBE2T-FANCL pair in vitro. FANCI interacts with FANCD2 through its C-terminal fragment (residues 1001–1328), and the FANCI-FANCD2 complex shows enhanced preference for branched DNA structures compared to either protein alone. In vitro DNA binding assays with purified protein, in vitro ubiquitination assay, co-immunoprecipitation with purified proteins, truncation and point mutation analysis The Journal of biological chemistry High 19561358 19589784
2009 Purified FANCI-FANCD2 complex preferentially binds branched DNA structures; FANCI interacts with FANCD2 through its C-terminal domain; two C-terminal patient-derived point mutations (R1285Q, D1301A) show altered DNA binding activity. Purified protein DNA binding assays, co-immunoprecipitation with purified proteins, truncation/point mutation analysis, immunofluorescence The Journal of biological chemistry High 19561358
2010 Mono-ubiquitinated FANCI-FANCD2 (ID) complex recruits FAN1 nuclease to sites of DNA damage to facilitate ICL repair; FAN1 recruitment strictly depends on monoubiquitination of the ID complex. Co-immunoprecipitation, chromatin fractionation, siRNA knockdown, cell-based ICL sensitivity assays Science High 20671156
2011 Crystal structure of the ~300 kDa FANCI-FANCD2 (ID) complex at 3.4 Å reveals that monoubiquitination and regulatory phosphorylation sites map to the I-D interface, suggesting these modifications occur on monomeric or opened-up complex and stabilize heterodimerization. Each protein has binding sites for both single- and double-stranded DNA. X-ray crystallography (3.4 Å crystal structure of ID complex; 7.8 Å electron density map of FANCI-DNA), in vitro DNA binding assays Science High 21764741
2011 RAD18 E3 ubiquitin ligase binds FANCD2 and is required for efficient monoubiquitination and chromatin localization of both FANCD2 and FANCI; the RING domain of RAD18 is required for this interaction and chromatin loading. Co-immunoprecipitation, chromatin fractionation, RAD18 knockout cells, RING domain mutation, immunofluorescence Blood Medium 21355096
2012 FANCD2 possesses nucleosome-assembly (histone chaperone) activity in vitro; FANCI alone lacks this activity but significantly stimulates FANCD2-mediated nucleosome assembly. FANCD2 mutations defective in nucleosome assembly impair cell survival after ICL damage. In vitro nucleosome assembly assay, histone mobility assays, FANCD2 knockdown, cisplatin sensitivity assays The EMBO journal Medium 22828868
2012 DNA (single-stranded, double-stranded, and branched forms) robustly stimulates FANCD2 monoubiquitination in vitro in a manner strictly requiring FANCI. A FANCI mutant defective in DNA binding is also defective in stimulating FANCD2 monoubiquitination, linking FANCI DNA binding to ubiquitination efficiency. In vitro reconstituted monoubiquitination assay with purified components and various DNA substrates; FANCI DNA-binding mutant analysis Nucleic acids research High 22287633
2012 FANCI phosphorylation by ATR is the molecular trigger for FANCD2-FANCI dissociation during DNA repair; phosphodead FANCI fails to dissociate from FANCD2, while phosphomimetic FANCI cannot interact with FANCD2. After dissociation, FANCD2 binds chromatin prior to and independently of FANCI. Phosphodead/phosphomimetic FANCI mutant analysis, co-immunoprecipitation, chromatin fractionation, cell-cycle analysis Nucleic acids research Medium 22753026
2013 FANCD2 regulates BLM complex (BLMcx) functions independently of FANCI: FANCD2 maintains BLM protein stability, recruits BLMcx to chromatin, and cooperates with BLM to promote replication fork restart. FANCI is dispensable for FANCD2-dependent BLMcx regulation, demonstrating functional separation. siRNA knockdown, co-immunoprecipitation, chromatin fractionation, DNA fiber assays, replication origin firing assays Nucleic acids research Medium 23658231
2013 Nuclear localization of a subset of FANCI depends on intact FANCD2 via an N-terminal FANCD2 nuclear localization signal; FANCD2 NLS mutation impairs both FANCD2 and FANCI nuclear localization, their monoubiquitination, and chromatin loading, resulting in ICL sensitivity. GFP fusion localization, NLS mutant analysis, Western blot, chromatin fractionation, ICL sensitivity complementation assays PloS one Medium 24278431
2014 FANCD2 monoubiquitination within the ID2 complex is strongly stimulated by duplex or branched DNA but not by unstructured single-stranded DNA; FANCI mutations that impair DNA binding compromise DNA-stimulated FANCD2 monoubiquitination. In the absence of FANCD2, DNA also stimulates FANCI monoubiquitination in a FANCL-independent manner. In vitro reconstituted monoubiquitination assay with UBE2T and FANCL, various DNA substrates, FANCI DNA-binding mutants Nucleic acids research High 24623813
2015 ATR-mediated phosphorylation of FANCI inhibits dormant origin firing while promoting replication fork restart/DNA repair. FANCI co-localizes with MCM-bound chromatin in response to replication stress, revealing a role for FANCI in regulating dormant origin firing independent of ICL repair. Super-resolution microscopy, DNA fiber assays, phosphomimetic/phosphodead mutant analysis, siRNA knockdown, chromatin fractionation Molecular cell High 25843623
2015 UBE2T (E2 ubiquitin-conjugating enzyme) is necessary for monoubiquitination of both FANCD2 and FANCI; loss of UBE2T abolishes FANCD2 and FANCI monoubiquitination and FANCD2 foci formation, causing Fanconi anemia (FA-T subtype). Patient fibroblast complementation, Western blot for monoubiquitination, immunofluorescence for FANCD2 foci, ICL sensitivity assays Cell reports High 26119737
2015 FANCI, but not FANCD2, is required for efficient recruitment of the FA core complex to sites of DNA damage (foci formation). This function requires FANCI deubiquitination by USP1 and is independent of FANCI monoubiquitination or ATR-dependent phosphorylation, placing FANCI upstream of FA core complex recruitment independently of FANCD2. Immunofluorescence foci assays, siRNA knockdown of FANCI/FANCD2/USP1, cell cycle analysis, epistasis experiments PLoS genetics Medium 26430909
2016 The cryo-EM structure of human FANCD2-FANCI complex reveals an inner cavity large enough to accommodate dsDNA and a protruding Tower domain; the complex is recruited to stalled replication forks before monoubiquitination, and this recruitment triggers the activating monoubiquitination event. FA patient mutations in the Tower domain are structurally rationalized. Cryo-EM structure determination, cell-based ICL recruitment assays, mutation analysis Nature communications High 27405460
2016 The FA core complex contains a homo-dimeric catalytic module (FANCB-FANCL-FAAP100 dimer of trimers) with two FANCL molecules positioned to target both FANCI and FANCD2 for mono-ubiquitination. FANCC-FANCE-FANCF subunits bridge between this module and the FANCI-FANCD2 substrate, transiently altering FANCI-FANCD2 configuration. Electron microscopy, crosslink-coupled mass spectrometry, biochemical reconstitution Cell reports High 27986592
2016 FANCI-FANCD2 (I-D) complex directly binds RAD51 and stabilizes the RAD51-DNA filament. FANCI DNA binding activity (but not FANCD2) is required for this stabilization. The stabilized RAD51 filament protects DNA ends from FAN1 nucleolytic degradation, explaining how the I-D complex protects stalled replication forks. In vitro pulldown and direct binding assays, DNA protection assays with FAN1, FANCI DNA-binding mutant analysis Nucleic acids research High 27694619
2016 FANCI forms a novel protein complex with Akt, PHLPP1, PHLPP2, FANCD2, USP1, and UAF1. Depletion of FANCI (but not FANCD2 or USP1) increases Akt phosphorylation/activation by reducing PHLPP1-Akt interaction, defining FANCI as a negative regulator of Akt activation. Co-immunoprecipitation, siRNA knockdown, Western blot for phospho-Akt, apoptosis assay Cell cycle Medium 27097374
2017 FANCI S/TQ cluster phosphorylation at serines 556, 559, and 565 occurs in two waves: S556 phosphorylation is ubiquitination-independent (upstream), while S559 and S565 phosphorylation is ubiquitination-linked (downstream). Ubiquitination-linked phosphorylation inhibits FANCD2 deubiquitination by USP1 and bypasses the need to deubiquitinate FANCD2 for effective ICL repair. Phospho-specific antibodies, ubiquitination-resistant/phosphomimetic mutants, USP1 depletion, ICL repair assays Cell reports High 28636932
2017 FANCI and FANCD2 associate with splicing factor SF3B1 (U2 snRNP component). Replication stress induces ATR-dependent release of SF3B1 from nuclear speckles in a FANCI-dependent manner. Both FANCI and FANCD2 associate with SF3B1 on chromatin, prevent accumulation of postcatalytic intron lariats, and contribute to timely eviction of splicing factors. Co-immunoprecipitation, proximity ligation assay, immunofluorescence, siRNA knockdown, RNA lariat analysis The Journal of cell biology Medium 29030393
2019 FANCI localizes to the nucleolus and functions in ribosome biogenesis independently of FANCD2: it is functionally linked to pre-rRNA transcription and large ribosomal subunit pre-rRNA processing. In the nucleolus, FANCI is predominantly in the deubiquitinated state, requiring both nucleoplasmic (USP1) and nucleolar (USP36) deubiquitinases. Immunofluorescence/nucleolar localization, siRNA knockdown, pre-rRNA processing assays, immunoprecipitation PNAS Medium 30692263
2019 Human FANCI-FANCD2 (ID2) complex binds single-stranded RNA (ssRNA) and R-loop substrates with high affinity, preferring guanine-rich sequences, by recognizing displaced ssDNA and ssRNA but not the RNA:DNA hybrid. RNA and R-loop substrates strongly stimulate ID2 monoubiquitination in proportion to their binding affinity. In vitro binding assays with purified ID2 and synthetic substrates, in vitro monoubiquitination assay, DART assay for in-cell R-loop colocalization Cell reports High 30650351
2019 FANCI interacts with FANCD2 via its in vitro binding; mutations in FANCI that impair FANCD2 binding (e.g., FANCD2 L231R equivalent) abolish ID complex formation and FANCD2 monoubiquitination and histone chaperone activity. In vitro binding assays with purified chicken FANCD2 L234R mutant, DT40 cell complementation, monoubiquitination assay, nucleosome assembly assay PloS one Medium 25489943
2019 FANCI interacts with PIDD1 to enable PIDDosome (PIDD1-RAIDD-caspase-2) assembly and apoptosis as an alternative to ICL repair with FANCD2. FANCI switches from FANCD2/repair to PIDD1/apoptosis when repair fails. Monoubiquitination (K523) and deubiquitination of FANCI impact interactor selection between FANCD2 and PIDD1. Co-immunoprecipitation, FANCI knockdown/knockout, caspase-2 activity assays, nuclease deletion epistasis, monoubiquitination site mutation (K523R) Developmental cell High 34256011
2019 CK2 phosphorylates a cluster of sites on FANCD2, inhibiting both FANCD2 recruitment to ICLs and its monoubiquitination in vitro and in vivo by reducing FANCD2 DNA binding activity, thereby suppressing FA pathway activation in the absence of damage. In vitro kinase assay, in vitro monoubiquitination assay, DNA binding assay, cell-based ICL sensitivity, phosphomimetic/phosphodead mutants Cell reports High 31167143
2020 Cryo-EM structures of chicken FANCD2-FANCI reveal that monoubiquitinated FANCD2 causes the complex to adopt a closed conformation that creates a channel enclosing dsDNA. Ubiquitin is positioned at the FANCD2-FANCI interface, acting as a covalent molecular pin to trap the complex on DNA. Unmodified FANCD2 forms a homodimer unable to bind DNA, suggesting autoinhibition. Cryo-EM structure determination, biochemical DNA binding assays, ubiquitination state analysis Nature structural & molecular biology High 32066963
2020 Reconstituted monoubiquitinated FANCI:FANCD2 does not promote specific exogenous protein-protein interactions but instead stabilizes FANCI:FANCD2 heterodimers on dsDNA (DNA clamping). Only FANCD2 monoubiquitination is required for clamping. Monoubiquitinated FANCI:FANCD2 forms filament-like arrays on long dsDNA. In vitro FA pathway reconstitution, electron microscopy, DNA binding assays, biochemical interaction assays eLife High 32167469
2020 ATR directly phosphorylates FANCI on S556, S559, and S565 to stabilize its association with DNA and FANCD2, stimulating conjugation of ubiquitin to both FANCI and FANCD2, and inhibiting deubiquitination. S559 and S565 are particularly important for protecting the complex from USP1:UAF1. Biochemical reconstitution with recombinant ATR, phosphomimetic/phosphodead FANCI mutants, in vitro ubiquitination/deubiquitination assays Frontiers in cell and developmental biology High 32117957
2020 FANCD2 ubiquitination promotes a large-scale conformational change in the ID2 complex increasing affinity for dsDNA by forming a secondary 'Arm' ID2 interface that encircles DNA. FANCI ubiquitination protects ubiquitin on FANCD2 from USP1-UAF1 deubiquitination, with key hydrophobic residues of FANCI's ubiquitin being important for this protection. Cryo-EM, biochemical deubiquitination assays with USP1-UAF1, DNA binding assays, ubiquitin mutant analysis EMBO reports High 32510829
2021 FANCI is required for spermatogenesis; FANCI deletion in mice causes male sterility with germ cell apoptosis and loss of undifferentiated spermatogonia. FANCI colocalizes with RPA on meiotic chromosomes, interacts with RAD51, and stimulates D-loop formation (unlike FANCD2), revealing a meiotic recombination function of FANCI independent of FANCD2. Fanci conditional knockout mouse model, meiotic chromosome immunofluorescence, D-loop assay, Co-IP with RAD51 Cell death & disease Medium 31219578 34373449
2022 Cryo-EM structures of FANCD2-FANCI with phosphomimetic FANCI show that phosphorylation destabilizes the open state and causes the complex to close around DNA independently of the FA core complex, priming the complex for ubiquitination. Phosphomimetic mutations do not substantially alter DNA binding but alter conformational dynamics. Cryo-EM structure determination with phosphomimetic FANCI, DNA binding assays, conformational dynamics analysis Nature structural & molecular biology High 36050501
2022 Cryo-EM structure of FANCI-ubiquitinated (IUb D2) complex shows it adopts the closed, DNA-encircling conformation with FANCD2 target lysine K561 exposed/primed for re-ubiquitination. FANCI ubiquitination maintains FANCD2 ubiquitination by both preventing deubiquitination within IUb D2Ub-DNA and enabling re-ubiquitination of FANCD2 within an IUb D2-DNA complex. Cryo-EM (4.1 Å structure), in vitro ubiquitination/deubiquitination assays, DNA binding assays The EMBO journal High 36385258
2024 Single-molecule imaging shows FANCD2-FANCI is a sliding clamp that diffuses on dsDNA and stalls specifically at ssDNA-dsDNA junctions (present at stalled replication forks). Cryo-EM structures of stalled D2-I show specific contacts with the ss-dsDNA junction distinct from sliding interactions, providing a unified mechanism for recognition and protection of stalled replication forks. Single-molecule TIRF imaging, cryo-EM structure determination on DNA substrates Nature High 39085614
2024 PP2A phosphatase complex specifically dephosphorylates an inhibitory cluster in FANCD2, licensing FANCD2/FANCI complex loading onto chromosomes and enabling monoubiquitination. In vitro reconstitution of coupled dephosphorylation-ubiquitination was achieved. Super-resolution live-cell imaging shows PP2A switches on the FA pathway at ICLs. In vitro reconstitution of PP2A dephosphorylation coupled to ubiquitination, super-resolution single-molecule live-cell tracking, PP2A inhibitor/knockdown experiments Cell reports High 39535917
2024 SRSF1 physically interacts with FANCD2 and acts together to suppress R-loop formation via mRNA export regulation. SRSF1 stimulates FANCD2 monoubiquitination in an RNA-dependent fashion; FANCD2 monoubiquitination is required for assembly of the SRSF1-NXF1 nuclear export complex and mRNA export. Cancer-associated SRSF1 mutants fail to interact with FANCD2, leading to defective monoubiquitination and R-loop accumulation. Co-immunoprecipitation, monoubiquitination assays, mRNA export assays, R-loop assays, SRSF1 mutant analysis Cell reports Medium 38165804
2010 FANCI patient-derived C-terminal mutant R1299X (deletion of 30 C-terminal residues) mislocalizes in cells. Within this 30-aa stretch are separable functional elements: a nuclear localization signal essential for nuclear targeting and robust FANCD2 monoubiquitination, and a putative EDGE motif important for DNA crosslink repair independent of localization. Patient-derived mutant analysis, immunofluorescence localization, complementation assays, ICL sensitivity Blood Medium 20971953
2010 In C. elegans, FANCI ortholog is required for FANCD2 focus formation and ubiquitination after ICL damage. FANCM and FANCI act upstream of FANCD2 activation in an ATR-CHK1-dependent pathway, establishing conservation of this signaling axis. Genetic epistasis in C. elegans, immunofluorescence foci assays, ubiquitination analysis, RNAi knockdown DNA repair Medium 20075016
2019 CTDP1 (a phosphatase with BRCT domain) interacts with FANCI and regulates multiple aspects of FANCI activity including chromatin localization, interaction with γ-H2AX, and SQ motif phosphorylations. CTDP1 knockdown reduces FANCI chromatin localization and impairs ICL repair. Co-immunoprecipitation, chromatin fractionation, phosphorylation assays, siRNA knockdown, ICL sensitivity assays Cell death discovery Low 31240132
2018 BRMS1 interacts with FANCI via BRMS1's linker region between two coiled-coil motifs. BRMS1 knockdown/knockout reduces FANCI and FANCD2 monoubiquitination and FANCD2 foci formation in response to ICL damage. BRMS1-FANCI interaction is required for BRMS1's regulatory role in the FA pathway. Co-immunoprecipitation, siRNA/CRISPR knockout, monoubiquitination Western blot, FANCD2 foci assays, rescue with BRMS1 deletion constructs Oncology reports Low 30365131

Source papers

Stage 0 corpus · 79 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2007 Identification of the FANCI protein, a monoubiquitinated FANCD2 paralog required for DNA repair. Cell 583 17412408
2007 FANCI is a second monoubiquitinated member of the Fanconi anemia pathway. Nature structural & molecular biology 230 17460694
2010 FAN1 acts with FANCI-FANCD2 to promote DNA interstrand cross-link repair. Science (New York, N.Y.) 209 20671156
2008 FANCI phosphorylation functions as a molecular switch to turn on the Fanconi anemia pathway. Nature structural & molecular biology 185 18931676
2008 Mechanistic insight into site-restricted monoubiquitination of FANCD2 by Ube2t, FANCL, and FANCI. Molecular cell 158 19111657
2015 ATR-mediated phosphorylation of FANCI regulates dormant origin firing in response to replication stress. Molecular cell 128 25843623
2011 Structure of the FANCI-FANCD2 complex: insights into the Fanconi anemia DNA repair pathway. Science (New York, N.Y.) 125 21764741
2015 Deficiency of UBE2T, the E2 Ubiquitin Ligase Necessary for FANCD2 and FANCI Ubiquitination, Causes FA-T Subtype of Fanconi Anemia. Cell reports 112 26119737
2007 Identification of the Fanconi anemia complementation group I gene, FANCI. Cellular oncology : the official journal of the International Society for Cellular Oncology 109 17452773
2020 FANCD2-FANCI is a clamp stabilized on DNA by monoubiquitination of FANCD2 during DNA repair. Nature structural & molecular biology 98 32066963
2013 FANCD2 regulates BLM complex functions independently of FANCI to promote replication fork recovery. Nucleic acids research 90 23658231
2009 FANCI binds branched DNA and is monoubiquitinated by UBE2T-FANCL. The Journal of biological chemistry 72 19589784
2012 A deletion in the bovine FANCI gene compromises fertility by causing fetal death and brachyspina. PloS one 71 22952632
2011 The E3 ubiquitin ligase RAD18 regulates ubiquitylation and chromatin loading of FANCD2 and FANCI. Blood 70 21355096
2019 Binding of FANCI-FANCD2 Complex to RNA and R-Loops Stimulates Robust FANCD2 Monoubiquitination. Cell reports 69 30650351
2012 DNA robustly stimulates FANCD2 monoubiquitylation in the complex with FANCI. Nucleic acids research 68 22287633
2014 Regulation of FANCD2 and FANCI monoubiquitination by their interaction and by DNA. Nucleic acids research 66 24623813
2016 The FANCD2-FANCI complex is recruited to DNA interstrand crosslinks before monoubiquitination of FANCD2. Nature communications 65 27405460
2020 Monoubiquitination by the human Fanconi anemia core complex clamps FANCI:FANCD2 on DNA in filamentous arrays. eLife 63 32167469
2015 FANCI Regulates Recruitment of the FA Core Complex at Sites of DNA Damage Independently of FANCD2. PLoS genetics 62 26430909
2019 Fanconi anemia protein FANCI functions in ribosome biogenesis. Proceedings of the National Academy of Sciences of the United States of America 55 30692263
2012 Histone chaperone activity of Fanconi anemia proteins, FANCD2 and FANCI, is required for DNA crosslink repair. The EMBO journal 54 22828868
2009 FANCI protein binds to DNA and interacts with FANCD2 to recognize branched structures. The Journal of biological chemistry 53 19561358
2016 The FA Core Complex Contains a Homo-dimeric Catalytic Module for the Symmetric Mono-ubiquitination of FANCI-FANCD2. Cell reports 50 27986592
2012 Fanconi anemia proteins FANCD2 and FANCI exhibit different DNA damage responses during S-phase. Nucleic acids research 48 22753026
2021 Oncogenic HPV promotes the expression of the long noncoding RNA lnc-FANCI-2 through E7 and YY1. Proceedings of the National Academy of Sciences of the United States of America 47 33436409
2016 FANCI-FANCD2 stabilizes the RAD51-DNA complex by binding RAD51 and protects the 5'-DNA end. Nucleic acids research 41 27694619
2019 A Fanci knockout mouse model reveals common and distinct functions for FANCI and FANCD2. Nucleic acids research 38 31219578
2020 Differential functions of FANCI and FANCD2 ubiquitination stabilize ID2 complex on DNA. EMBO reports 37 32510829
2017 FANCI and FANCD2 have common as well as independent functions during the cellular replication stress response. Nucleic acids research 33 29059323
2019 Phosphorylation of FANCD2 Inhibits the FANCD2/FANCI Complex and Suppresses the Fanconi Anemia Pathway in the Absence of DNA Damage. Cell reports 31 31167143
2020 ATR-Mediated FANCI Phosphorylation Regulates Both Ubiquitination and Deubiquitination of FANCD2. Frontiers in cell and developmental biology 30 32117957
2017 Ubiquitination-Linked Phosphorylation of the FANCI S/TQ Cluster Contributes to Activation of the Fanconi Anemia I/D2 Complex. Cell reports 30 28636932
2021 Mechanism, specificity, and function of FANCD2-FANCI ubiquitination and deubiquitination. The FEBS journal 28 34137174
2009 Mutational analysis of FANCL, FANCM and the recently identified FANCI suggests that among the 13 known Fanconi Anemia genes, only FANCD1/BRCA2 plays a major role in high-risk breast cancer predisposition. Carcinogenesis 28 19737859
2016 FANCI is a negative regulator of Akt activation. Cell cycle (Georgetown, Tex.) 27 27097374
2015 Novel FANCI mutations in Fanconi anemia with VACTERL association. American journal of medical genetics. Part A 26 26590883
2024 The FANCI/FANCD2 complex links DNA damage response to R-loop regulation through SRSF1-mediated mRNA export. Cell reports 25 38165804
2016 A FANCD2/FANCI-Associated Nuclease 1-Knockout Model Develops Karyomegalic Interstitial Nephritis. Journal of the American Society of Nephrology : JASN 25 27026368
2022 The DNA-damage kinase ATR activates the FANCD2-FANCI clamp by priming it for ubiquitination. Nature structural & molecular biology 24 36050501
2010 The involvement of FANCM, FANCI, and checkpoint proteins in the interstrand DNA crosslink repair pathway is conserved in C. elegans. DNA repair 24 20075016
2017 Fanconi anemia FANCD2 and FANCI proteins regulate the nuclear dynamics of splicing factors. The Journal of cell biology 22 29030393
2024 FANCD2-FANCI surveys DNA and recognizes double- to single-stranded junctions. Nature 21 39085614
2021 FANCI plays an essential role in spermatogenesis and regulates meiotic histone methylation. Cell death & disease 21 34373449
2019 CTDP1 regulates breast cancer survival and DNA repair through BRCT-specific interactions with FANCI. Cell death discovery 21 31240132
2020 FANCI Cooperates with IMPDH2 to Promote Lung Adenocarcinoma Tumor Growth via a MEK/ERK/MMPs Pathway. OncoTargets and therapy 19 32021289
2010 Patient-derived C-terminal mutation of FANCI causes protein mislocalization and reveals putative EDGE motif function in DNA repair. Blood 17 20971953
2015 FANCJ protein is important for the stability of FANCD2/FANCI proteins and protects them from proteasome and caspase-3 dependent degradation. Oncotarget 16 26336824
2020 Structural insight into FANCI-FANCD2 monoubiquitination. Essays in biochemistry 15 32725171
2022 UBE2T regulates FANCI monoubiquitination to promote NSCLC progression by activating EMT. Oncology reports 14 35703356
2021 FANCI functions as a repair/apoptosis switch in response to DNA crosslinks. Developmental cell 14 34256011
2021 A functionally impaired missense variant identified in French Canadian families implicates FANCI as a candidate ovarian cancer-predisposing gene. Genome medicine 14 34861889
2019 Enzymatic preparation of monoubiquitinated FANCD2 and FANCI proteins. Methods in enzymology 14 30850063
2022 Structural and biochemical basis of interdependent FANCI-FANCD2 ubiquitination. The EMBO journal 13 36385258
2020 Inactivation of ribosomal protein S27-like impairs DNA interstrand cross-link repair by destabilization of FANCD2 and FANCI. Cell death & disease 12 33051438
2013 Coordinate nuclear targeting of the FANCD2 and FANCI proteins via a FANCD2 nuclear localization signal. PloS one 12 24278431
2024 FANCI Inhibition Induces PARP1 Redistribution to Enhance the Efficacy of PARP Inhibitors in Breast Cancer. Cancer research 9 39037758
2022 Silencing of FANCI Promotes DNA Damage and Sensitizes Ovarian Cancer Cells to Carboplatin. Current cancer drug targets 9 35362384
2024 Novel compound heterozygous variants in FANCI cause premature ovarian insufficiency. Human genetics 6 38483614
2023 Molecular Genetic Characteristics of FANCI, a Proposed New Ovarian Cancer Predisposing Gene. Genes 6 36833203
2023 TXNL4B regulates radioresistance by controlling the PRP3-mediated alternative splicing of FANCI. MedComm 6 37168687
2014 Defective FANCI binding by a fanconi anemia-related FANCD2 mutant. PloS one 6 25489943
2023 Fanconi anemia pathway regulation by FANCI in prostate cancer. Frontiers in oncology 5 38023254
2014 Expression and purification of human FANCI and FANCD2 using Escherichia coli cells. Protein expression and purification 4 25168188
2025 The long noncoding RNA lnc-FANCI-2 intrinsically restricts RAS signaling in human papillomavirus type 16-infected cervical cancer cells. eLife 3 40878909
2024 PP2A licenses the FANCD2/FANCI complex for chromosome loading. Cell reports 3 39535917
2020 Generation of a human induced pluripotent stem cell line (CMCi001-A) from a patient with karyomegalic interstitial nephritis with homozygous frameshift deletion mutation c.1985_1994del10 of the FANCD2/FANCI-Associated Nuclease 1 gene. Stem cell research 3 32563974
2018 BRMS1 participates in regulating cell sensitivity to DNA interstrand crosslink damage by interacting with FANCI. Oncology reports 3 30365131
2016 Structural and biophysical properties of h-FANCI ARM repeat protein. Journal of biomolecular structure & dynamics 3 27686023
2025 Expression and clinical significance of FANCI gene in pan-cancer: a comprehensive analysis based on multi-omics data. Frontiers in genetics 2 40417238
2026 Betulinic Acid Suppresses UBE2T Expression via MAPK/ERK Inhibition to Block FANCI and FANCD2 Monoubiquitination in Glioblastoma. Journal of cellular and molecular medicine 1 41486508
2025 Knockdown of FANCI suppresses hepatocellular carcinoma development via the PI3K/Akt/GSK-3β pathway. Heliyon 1 40040987
2024 Novel FANCI and RAD54B Variants and the Observed Clinical Outcomes in a Hungarian Melanoma Cohort. International journal of molecular sciences 1 39795882
2026 The FANCD2-FANCI heterodimer coordinates chromatin openness and cell cycle progression throughout DNA double-strand break repair. Cell reports 0 41505257
2026 Possible link between the apparently pathogenic FANCI variant and beneficial effects in sports performance. Frontiers in genetics 0 41732159
2025 FANCI is involved in the malignant progression of glioma cells by regulating the Akt/Bcl-2 signaling pathway. Discover oncology 0 40358883
2025 Arabidopsis thaliana FANCONI ANAEMIA I (FANCI) has roles in the repair of interstrand crosslinks and CRISPR-Cas9 induced DNA double strand breaks. The Plant journal : for cell and molecular biology 0 41122064
2024 SSX2IP promotes cell proliferation and migration in breast cancer by regulating FANCI. Cell biology international 0 39533770
2022 Genetic Study of Fanconi Anemia in Infancy Revealed FANCI Mutations and Defective ALDH2 Variant: A Case Report. Journal of pediatric hematology/oncology 0 34310468