{"gene":"APOBEC3G","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":2003,"finding":"APOBEC3G exerts its antiviral effect during reverse transcription by triggering G-to-A hypermutation in nascent retroviral DNA, acting as a cytidine deaminase that converts dC to dU in minus-strand reverse transcripts.","method":"Retroviral infection assays, hypermutation analysis of viral DNA","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro and cell-based demonstration of deaminase activity on viral DNA, independently replicated by multiple labs (PMIDs 12808466 and 12808465)","pmids":["12808466","12808465"],"is_preprint":false},{"year":2003,"finding":"HIV-1 Vif interacts with cellular proteins Cul5, elongins B and C, and Rbx1 to form an SCF-like E3 ubiquitin ligase complex that induces polyubiquitination and proteasomal degradation of APOBEC3G.","method":"Co-immunoprecipitation, ubiquitination assays, proteasome inhibitor studies","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP identifying the full complex, functional mutagenesis of Vif, replicated across multiple labs (PMIDs 14564014, 14528300, 14528301)","pmids":["14564014","14528300","14528301"],"is_preprint":false},{"year":2003,"finding":"HIV-1 Vif prevents APOBEC3G incorporation into progeny virions and induces its proteasomal degradation via ubiquitination, thereby allowing infection to proceed without viral DNA deamination.","method":"Virion fractionation, proteasome inhibitor assays, immunoprecipitation","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct virion incorporation assays and proteasome inhibitor studies, replicated across multiple labs (PMIDs 14528300, 14528301, 14527406)","pmids":["14528300","14528301","14527406"],"is_preprint":false},{"year":2003,"finding":"HIV-1 Vif physically binds APOBEC3G and forms a complex with it; species-specific differences in this interaction explain why HIV-1 Vif does not efficiently complex with mouse APOBEC3G.","method":"Co-immunoprecipitation, virion encapsidation assays","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with species-specificity controls, replicated across multiple labs (PMIDs 12859895, 14528301)","pmids":["12859895","14528301"],"is_preprint":false},{"year":2003,"finding":"Vif impairs both the translation of APOBEC3G mRNA and accelerates posttranslational degradation of the protein by the 26S proteasome, acting through direct physical interaction with APOBEC3G.","method":"Western blot with proteasome inhibitors, pulse-chase analysis, immunoprecipitation, endogenous APOBEC3G-specific antiserum","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — two orthogonal mechanisms demonstrated with specific antiserum against endogenous protein, single lab but multiple methods","pmids":["14527406"],"is_preprint":false},{"year":2004,"finding":"APOBEC3G is recruited to the membrane and packaged into HIV-1 Gag virus-like particles through interaction with the nucleocapsid (NC) domain of Gag; amino acids 104-156 of APOBEC3G are required for this incorporation, and Gag alone (without other viral proteins) is sufficient for packaging.","method":"Co-immunoprecipitation, virus-like particle fractionation, deletion mutagenesis","journal":"Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus deletion mutagenesis mapping, corroborated by independent lab (PMID 15358144)","pmids":["15159405","15358144"],"is_preprint":false},{"year":2004,"finding":"APOBEC3G is a single-stranded DNA cytidine deaminase that deaminates cDNA independently of reverse transcriptase; deamination requires the cDNA to be free of its RNA template (RNase H-dependent exposure of ssDNA).","method":"In vitro deaminase assay with baculovirus-derived APOBEC3G, RNase H-deficient RT experiments","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified protein, multiple controls including RNase H-deficient RT","pmids":["15121899"],"is_preprint":false},{"year":2005,"finding":"APOBEC3G antiviral activity can be dissociated from cytidine deaminase activity: the N-terminal domain (CD1) can confer antiviral function without DNA mutator activity, whereas the C-terminal domain (CD2) is essential for deaminase activity. Only the C-terminal catalytic motif is required for DNA hypermutation.","method":"Site-directed mutagenesis of catalytic motifs, infectivity assays, deaminase activity assays","journal":"Current Biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site mutagenesis of both catalytic domains with functional readouts for both deaminase and antiviral activity","pmids":["15668174"],"is_preprint":false},{"year":2005,"finding":"APOBEC3G's N-terminal domain (CD1) mediates RNA binding and virion encapsidation through zinc-coordination residues and conserved aromatic residues, while the C-terminal domain (CD2) mediates cytidine deaminase activity; the two domains have complementary but non-redundant functions.","method":"Deletion and point mutagenesis, RNA binding assays, virion encapsidation assays","journal":"Virology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic mutagenesis of both domains with multiple functional readouts (RNA binding, encapsidation, deaminase activity)","pmids":["15721369"],"is_preprint":false},{"year":2006,"finding":"APOBEC3G acts processively on single-stranded DNA in the 3'→5' direction by a combination of jumping and sliding mechanisms, without requiring a nucleotide cofactor, explaining the G-to-A mutational gradient observed in viral DNA.","method":"In vitro biochemical deamination assays, processivity measurements on ssDNA substrates","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — rigorous in vitro biochemical reconstitution with multiple substrate configurations, single lab with multiple orthogonal approaches","pmids":["16622407"],"is_preprint":false},{"year":2006,"finding":"APOBEC3G localizes to P bodies and stress granules as part of high-molecular-weight ribonucleoprotein (RNP) complexes; it associates with Argonaute 1 and Argonaute 2 in an RNase-resistant manner, and redistributes to stress granules upon cellular stress.","method":"Tandem affinity purification/mass spectrometry, confocal microscopy, RNase treatment co-immunoprecipitation","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — TAP-MS plus confocal microscopy showing localization with functional stress-response redistribution, two orthogonal methods","pmids":["17166910"],"is_preprint":false},{"year":2006,"finding":"High-molecular-mass (HMM) APOBEC3G complexes, which contain Staufen-containing RNA-transporting granules and Ro RNP complexes loaded with Alu and small Y RNAs, restrict Alu retrotransposition by sequestering Alu RNAs in cytoplasmic HMM complexes rather than by inhibiting L1 reverse transcriptase function.","method":"Tandem affinity purification/MS, Alu retrotransposition reporter assay, RNA analysis","journal":"PNAS","confidence":"High","confidence_rationale":"Tier 2 / Moderate — TAP-MS identification of complex components plus functional retrotransposition assay distinguishing mechanism (sequestration vs. L1 inhibition)","pmids":["17030807"],"is_preprint":false},{"year":2007,"finding":"APOBEC3G inhibits HIV-1 minus- and plus-strand DNA transfer steps during reverse transcription independently of its editing activity; this inhibition correlates with its ability to prevent RNase H degradation of the RNA template.","method":"In vivo viral cDNA intermediate analysis, in vitro strand transfer assay","journal":"Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — combined in vivo and in vitro assays with deaminase-dead mutant controls, single lab","pmids":["17855362"],"is_preprint":false},{"year":2007,"finding":"7SL RNA selectively interacts with APOBEC3G and is preferentially packaged into HIV-1 particles via the nucleocapsid domain of Gag; APOBEC3G mutants with reduced 7SL RNA binding are packaged poorly and have impaired antiviral activity.","method":"RNA-binding assays, virion encapsidation assays, SRP19 overexpression to competitively reduce 7SL RNA","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional co-packaging assays with mutants and competitive inhibition, single lab","pmids":["17881443"],"is_preprint":false},{"year":2007,"finding":"APOBEC3G inhibits HIV-1 reverse transcription elongation in a deaminase-independent manner; in cell-free virions, A3G impedes elongation of cDNA products without requiring target cell factors.","method":"Endogenous reverse transcriptase assay in cell-free virions","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-free endogenous RT assay directly measuring elongation, single lab","pmids":["19057663"],"is_preprint":false},{"year":2007,"finding":"APOBEC3G inhibits RT-catalyzed DNA elongation reactions in a deaminase-independent manner by competing with RT for ssDNA binding; NC has faster nucleic acid association/dissociation kinetics than A3G, while RT binds ssDNA with much lower affinity than A3G.","method":"In vitro primer extension assays, fluorescence anisotropy, single-molecule DNA stretching","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal in vitro methods (primer extension, fluorescence anisotropy, single-molecule), rigorous kinetic analysis","pmids":["17942420"],"is_preprint":false},{"year":2008,"finding":"The solution structure of the APOBEC3G catalytic (C-terminal) domain reveals five alpha-helices arranged over a hydrophobic beta-strand platform with a zinc-coordinating active site; NMR DNA titration and mutagenesis define a DNA-binding model with positively charged residues positioning the target cytosine for catalysis.","method":"NMR structure determination, DNA titration NMR, computational modelling, E. coli-based activity assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure with functional validation by mutagenesis and activity assays, multiple orthogonal methods in single study","pmids":["18288108"],"is_preprint":false},{"year":2008,"finding":"Protein kinase A (PKA) binds and phosphorylates APOBEC3G at Thr32 in vitro and in vivo; this phosphorylation reduces A3G binding to Vif, diminishes Vif-induced ubiquitination and degradation, and promotes antiviral activity.","method":"In vitro kinase assay, co-immunoprecipitation, mutagenesis, structural modeling","journal":"Nature structural & molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro kinase assay plus cell-based Co-IP and mutagenesis, single lab with two orthogonal methods","pmids":["18836454"],"is_preprint":false},{"year":2008,"finding":"APOBEC3G is exclusively retained in the cytoplasm and does not undergo nucleo-cytoplasmic shuttling; this cytoplasmic retention requires both the N- and C-terminal regions of the protein.","method":"Live-cell imaging, subcellular fractionation, heterokaryon assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiments with multiple protein regions tested, single lab","pmids":["16999936"],"is_preprint":false},{"year":2009,"finding":"APOBEC3G oligomerization is RNA-dependent and requires tyrosine-124 and tryptophan-127 in the N-terminal CDA domain; these oligomerization-mediating residues also coincide with virion packaging determinants. Arginine residues at positions 24, 30, and 136 in a positively charged pocket promote RNA-dependent oligomerization and virion packaging.","method":"Yeast two-hybrid, co-immunoprecipitation, chemical crosslinking, homology modeling, mutational analysis","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — three orthogonal methods (Y2H, Co-IP, crosslinking) plus structural modeling and mutagenesis, single lab","pmids":["19266078"],"is_preprint":false},{"year":2009,"finding":"HIV-1 Vif directly binds to APOBEC3G mRNA (with higher affinity for the 3'UTR) and inhibits its translation by two mechanisms: a time-independent process requiring the 5'UTR and an additional UTR-independent process.","method":"Filter binding assays, fluorescence titration, RNase footprinting, in vitro translation assays","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro binding and translation assays with defined RNA regions, single lab","pmids":["19910370"],"is_preprint":false},{"year":2010,"finding":"APOBEC3G inhibits HIV-1 DNA integration by generating a 6-bp extension at the viral U5 end of the 3'-LTR (a poor substrate for integration), dependent on a functional C-terminal catalytic domain; this mechanism is distinct from that of APOBEC3F.","method":"Southern blot analysis of viral cDNA processing, integration assays, mutational analysis","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Southern blot mapping of specific DNA end-processing defects with catalytic domain mutants, single lab","pmids":["20219927"],"is_preprint":false},{"year":2010,"finding":"APOBEC3G exists as monomers, dimers, tetramers, and higher-order oligomers; the CD1 domain is essential for both processivity and 3'→5' deamination polarity. A CD1-CD1 dimer interface mutant (F126A/W127A) predominantly converts A3G to a monomer that retains ssDNA binding, Alu RNA binding, and processive deaminase activity.","method":"Multiangle light scattering, atomic force microscopy, mutagenesis, deaminase activity assays","journal":"Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal structural/biochemical methods (MALS, AFM) plus mutagenesis and functional assays, single lab","pmids":["20212048"],"is_preprint":false},{"year":2011,"finding":"Vif additionally recruits the transcription cofactor CBF-β to the Vif-CUL5-ELOC-ELOB-RBX ubiquitin ligase complex; CBF-β is required for Vif-mediated APOBEC3G degradation and a reconstituted six-protein assembly elicits specific polyubiquitination of APOBEC3G but not APOBEC3A.","method":"Affinity tag/purification mass spectrometry, RNA knockdown, genetic complementation, reconstituted in vitro ubiquitination assay","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — AP-MS discovery plus reconstituted in vitro ubiquitination assay plus RNAi rescue, multiple orthogonal methods, single lab with rigorous controls","pmids":["22190037"],"is_preprint":false},{"year":2012,"finding":"APOBEC3G directly interacts with HIV-1 reverse transcriptase (RT); the RT-binding region of A3G maps to amino acids 65-132. This interaction disrupts RT function and plays an important role in A3G's deaminase-independent inhibition of reverse transcription.","method":"Cell-based co-immunoprecipitation, deletion analysis, overexpression of binding-domain peptide to competitively disrupt interaction","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus competitive disruption experiment, single lab, no in vitro reconstitution","pmids":["22301159"],"is_preprint":false},{"year":2012,"finding":"APOBEC3G accumulates transiently in the nucleus in response to ionizing radiation, is recruited to DNA double-strand break (DSB) repair foci, and promotes DSB repair in a deaminase-dependent manner; AFM shows that A3G multimers associate with ssDNA termini at DSBs.","method":"Nuclear fractionation, immunofluorescence recruitment to DSB foci, siRNA knockdown with DSB repair assay, reporter cassette, atomic force microscopy","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization to DSB foci plus functional rescue experiment and AFM, single lab","pmids":["22645179"],"is_preprint":false},{"year":2013,"finding":"APOBEC3G initially binds ssDNA with rapid on-off rates and subsequently converts to a slowly dissociating mode through oligomerization; an oligomerization-deficient mutant does not exhibit the slow off rate, suggesting catalytically active monomers/dimers oligomerize on the viral genome to inhibit reverse transcription.","method":"Single-molecule DNA stretching, fluorescence anisotropy, oligomerization mutant analysis","journal":"Nature chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — single-molecule biophysics plus fluorescence anisotropy with oligomerization-deficient mutant, multiple orthogonal methods","pmids":["24345943"],"is_preprint":false},{"year":2013,"finding":"RNA binding by APOBEC3G (via tryptophan residues W94 and W127 in the N-terminal domain) is specifically required for deamination-independent restriction of retroviruses, including inhibition of late reverse transcript accumulation and prevention of proviral DNA integration; deaminase activity does not significantly contribute to restriction of these processes.","method":"Mutagenesis of RNA-binding residues, retroviral infectivity assays, RT product quantification, integration assays","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional mutagenesis with multiple downstream readouts, single lab","pmids":["23761443"],"is_preprint":false},{"year":2013,"finding":"APOBEC3G and P-body localization to processing bodies is not required for virion incorporation or antiviral activity; sucrose gradient analysis shows the majority of A3G is in high-molecular-mass RNA-protein complexes distinct from canonical P-body markers.","method":"DDX6 knockdown to disrupt P bodies, SRP19 overexpression to deplete A3G from P bodies, sucrose gradient sedimentation","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — P-body disruption by two independent methods with virion incorporation readout, single lab","pmids":["23926332"],"is_preprint":false},{"year":2015,"finding":"NMR structure of the APOBEC3G N-terminal (Vif-binding) domain reveals a smaller zinc-coordinating pocket and altered helical packing compared to the catalytic domain; the Vif-interacting surface is formed by loops α1-β1, β2-α2, and β4-α4, identified by mutagenesis and biochemical binding experiments.","method":"NMR structure determination (evolution- and structure-guided solubilizing mutations), mutagenesis, biochemical binding assays","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — NMR structure with functional mutagenesis validation of Vif-binding surface, multiple orthogonal methods","pmids":["25984970"],"is_preprint":false},{"year":2015,"finding":"HDAC6 directly interacts with APOBEC3G through its C-terminal BUZ domain and co-distributes along microtubules; HDAC6 also interacts with Vif and promotes its autophagic degradation (requiring HDAC6 deacetylase activity), thereby stabilizing A3G and increasing its incorporation into virions.","method":"Co-immunoprecipitation, domain mapping, autophagy inhibitor assays, virion fractionation","journal":"Retrovirology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP domain mapping plus functional autophagy assays, single lab","pmids":["26105074"],"is_preprint":false},{"year":2015,"finding":"ASK1 (apoptosis signal-regulating kinase 1) binds the BC-box of Vif, disrupting assembly of the Vif-ubiquitin ligase complex, thereby stabilizing A3G and promoting its incorporation into viral particles; AZT treatment induces ASK1 expression, restoring A3G antiviral activity.","method":"Co-immunoprecipitation, ubiquitin ligase complex assembly assays, virion fractionation, viral infectivity assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional complex disruption assays, single lab","pmids":["25901786"],"is_preprint":false},{"year":2016,"finding":"Crystal structure of a primate A3G N-terminal domain (CD1) alone and in complex with ssDNA shows the dimerization interface and reveals conformational changes in loops around the zinc-coordinated center upon DNA binding; the CD1 dimerization interface is important for oligomerization, nucleic acid binding, and Vif-mediated degradation.","method":"X-ray crystallography, mutagenesis, functional assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with ssDNA-bound and apo forms plus mutagenesis validation of functional relevance, single lab","pmids":["27480941"],"is_preprint":false},{"year":2016,"finding":"APOBEC3G causes site-specific C-to-U editing of mRNAs from over 600 genes, requiring conserved catalytic residues in both N-terminal and C-terminal cytidine deaminase domains; APOBEC3G co-purifies with highly edited mRNA substrates.","method":"Transcriptome-wide RNA-seq, active-site mutagenesis of both catalytic domains, RNA co-purification","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transcriptome-wide sequencing plus mutagenesis of both catalytic domains, single lab, novel finding","pmids":["27974822"],"is_preprint":false},{"year":2017,"finding":"Deep sequencing of HIV-1 reverse transcripts in infected T cells demonstrates that A3G inhibits reverse transcription in a site- and sequence-independent manner that requires direct interaction with reverse transcriptase; cellular uracil base excision repair (UBER) enzymes target and cleave A3G-edited uridine-containing viral cDNA.","method":"Deep sequencing of nascent reverse transcription products, A3G-RT interaction studies, UBER inhibitor assays","journal":"Nature microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — novel deep-sequencing strategy in primary T cells plus mechanistic A3G-RT interaction and UBER pathway, multiple orthogonal findings in one study","pmids":["29158605"],"is_preprint":false},{"year":2017,"finding":"APOBEC3G first binds ssDNA as a catalytically active monomer, then forms N-terminal domain-mediated dimers whose dissociation from DNA is reduced and deaminase activity is inhibited; this dimerization-to-inactivation mechanism may create enzymatically deficient roadblocks that inhibit reverse transcription.","method":"Single-molecule DNA stretching, fluorescence assays with wild-type and oligomerization-deficient A3G mutants","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — single-molecule biophysics with oligomerization mutants, single lab","pmids":["28928403"],"is_preprint":false},{"year":2019,"finding":"APOBEC3G induces widespread site-specific C-to-U mRNA editing in natural killer cells and lymphoma cell lines under conditions of cellular crowding and hypoxia (mimicked by mitochondrial respiration inhibition), independently of HIF-1α; this editing is enriched for genes involved in mRNA translation and ribosome function.","method":"RNA-seq in primary NK cells, mitochondrial inhibitors, HIF-1α knockout controls, metabolic assays","journal":"Genome biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transcriptome-wide RNA-seq in primary cells with mechanistic controls (inhibitors, KO), single lab","pmids":["30791937"],"is_preprint":false},{"year":2019,"finding":"USP49 directly interacts with APOBEC3G and efficiently removes ubiquitin from it, stabilizing A3G protein expression and enhancing its anti-HIV-1 activity; A3G degradation also occurs via a Vif- and cullin-ring-independent pathway that USP49 counteracts.","method":"Co-immunoprecipitation, in vitro deubiquitination assay, proteasome pathway dissection, clinical sample correlation","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional deubiquitination assays with pathway mutants, single lab","pmids":["31397674"],"is_preprint":false},{"year":2020,"finding":"Full-length rhesus macaque A3G cryo-EM/crystal structures reveal different inter-domain packing through a short linker and refolding of CD2; A3G dimerization generates a surface with intensified positive electrostatic potential for RNA binding and dimer stabilization, though mutating this surface does not abolish virion packaging.","method":"Cryo-EM and X-ray crystallography of full-length A3G, mutagenesis, virion packaging assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — full-length protein structures by two methods plus functional mutagenesis, single lab","pmids":["32005813"],"is_preprint":false},{"year":2023,"finding":"Cryo-EM structure of human APOBEC3G bound to HIV-1 Vif in complex with CBF-β and the CUL5-RING E3 ubiquitin ligase reveals that RNA acts as molecular glue for the Vif-A3G interaction; Vif makes contact primarily through A3G's non-catalytic N-terminal domain while the catalytic domain is positioned for ubiquitin transfer. Vif can repress A3G by both ubiquitin-dependent and ubiquitin-independent mechanisms.","method":"Cryo-electron microscopy structure determination, biochemical binding assays, mutagenesis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure of full complex with independent confirmation from a second cryo-EM study (PMID 36598981), multiple mechanistic insights validated by mutagenesis","pmids":["36754086","36598981"],"is_preprint":false},{"year":2004,"finding":"Transcription of APOBEC3G in human T lymphocytes is controlled by the PKCα/βI–MEK–ERK protein kinase cascade; PKCα/βI/MEK/ERK pathway inhibitors reduce both basal and induced APOBEC3G mRNA/protein levels, and this pathway is activated by phorbol myristate acetate.","method":"Pharmacological inhibitor studies, luciferase reporter assays, RT-PCR and western blot","journal":"Journal of Biological Chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple inhibitors at distinct pathway steps converging on the same outcome, single lab","pmids":["15297452"],"is_preprint":false},{"year":2007,"finding":"Basal transcription of the APOBEC3G gene is regulated by transcription factors Sp1 and Sp3 through a GC-box element at position -87/-78 relative to the major transcriptional start site; mutation of this GC-box abolishes promoter activity.","method":"Luciferase reporter assays, EMSA, chromatin immunoprecipitation (ChIP), 5' RACE","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA plus ChIP plus reporter assay with GC-box mutation, single lab","pmids":["17517765"],"is_preprint":false},{"year":2006,"finding":"IFN-α induces APOBEC3G expression in liver cells and macrophages but not in T cells or epithelial cells; this induction is STAT1-independent but STAT2-dependent in liver cells, revealing a non-canonical IFN-α signaling pathway for A3G regulation.","method":"Cytokine treatment, pathway inhibitors (Rottlerin), STAT1-deficient cells, western blot/RT-PCR","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — STAT1-null cells plus specific inhibitor corroborating STAT2-dependence, single lab","pmids":["16982890"],"is_preprint":false},{"year":2008,"finding":"The prolyl isomerase Pin1 interacts with APOBEC3G and reduces its expression and incorporation into HIV-1 virions; HIV-1 infection modulates Pin1 phosphorylation state, enhancing its ability to decrease A3G activity.","method":"Co-immunoprecipitation, virion incorporation assays, HIV infection modulation of Pin1","journal":"Journal of virology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP identification plus functional readout, single lab, limited mechanistic follow-up","pmids":["18684817"],"is_preprint":false},{"year":2011,"finding":"RNA directly suppresses APOBEC3G ssDNA deaminase activity in a concentration-dependent manner; RNA forms RNP complexes with A3G that prevent ssDNA substrates from binding; RNAs as short as 25 nt and of diverse sequences are effective inhibitors.","method":"In vitro deaminase assay with defined RNA concentrations, native PAGE gel-shift analysis","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified components plus native PAGE showing competitive displacement of ssDNA by RNA","pmids":["21856286"],"is_preprint":false},{"year":2015,"finding":"RNA stochastically dissociates APOBEC3G dimers and higher-order oligomers from ssDNA; mass spectrometry cross-linking maps distinct A3G peptide surfaces for ssDNA binding (aa 181-194, 314-320, 345-374) versus RNA binding (same surfaces plus additional N-terminal peptides aa 15-29, 41-52, 83-99), suggesting RNA inhibition occurs through both competitive and allosteric mechanisms.","method":"Native PAGE, fluorescence anisotropy, cross-linking mass spectrometry peptide mapping","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cross-linking MS plus fluorescence anisotropy plus native PAGE, multiple orthogonal methods in single study","pmids":["26424853"],"is_preprint":false},{"year":2017,"finding":"Both APOBEC3A and APOBEC3G prefer RNA substrates with a stem-loop structure where the reactive cytidine is at the 3'-end of the loop; loop size, nucleotides 5' of the target C, and stem stability all influence editing efficiency.","method":"Mutagenesis of endogenous RNA substrates, RNA editing assays","journal":"PeerJ","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic mutagenesis of natural RNA substrates with functional editing assays, single lab","pmids":["29230368"],"is_preprint":false},{"year":2018,"finding":"Crystal structure of APOBEC3G catalytic domain in complex with ssDNA (via Pot1-fusion anchoring strategy) reveals a unique conformation of catalytic-site loops; nucleotide-binding pockets at the -1 and active-site positions influence each other in selecting the preferred CCCA substrate sequence.","method":"X-ray crystallography with Pot1-fusion strategy, biochemical deaminase assays, HIV infectivity assays","journal":"PLoS one","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — crystal structure plus biochemical and virological validation, single lab","pmids":["29596531"],"is_preprint":false},{"year":2017,"finding":"APOBEC3G-mediated C-to-U mRNA editing requires stem-loop RNA secondary structure with the target cytidine at the 3'-end of the loop, and APOBEC3G edits sites largely distinct from those targeted by APOBEC3A.","method":"Transcriptome RNA-seq, mutagenesis of RNA substrates","journal":"PeerJ","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — comparative RNA-seq plus substrate mutagenesis, single lab","pmids":["29230368"],"is_preprint":false}],"current_model":"APOBEC3G is a cytoplasmic single-stranded DNA/RNA cytidine deaminase that is packaged into HIV-1 virions (via RNA-dependent oligomerization and interaction with Gag nucleocapsid), where it restricts HIV-1 replication through two main mechanisms: (1) processive 3'→5' deamination of minus-strand viral cDNA causing lethal G-to-A hypermutation, and (2) deaminase-independent inhibition of reverse transcriptase elongation and strand-transfer steps through direct RT interaction and RNA-mediated roadblocking; its activity is regulated by molecular state (low-molecular-mass active form vs. high-molecular-mass RNA-bound inactive HMM complexes), by PKA phosphorylation at Thr32, by Sp1/Sp3-driven basal transcription and PKCα/MEK/ERK-driven inducible transcription, and by the deubiquitinase USP49; HIV-1 Vif counteracts A3G by recruiting a CBF-β–CUL5–ELOB–ELOC–RBX E3 ubiquitin ligase complex (structure resolved by cryo-EM) that polyubiquitinates A3G for proteasomal degradation, with RNA serving as molecular glue for the Vif–A3G interface; additionally, A3G performs site-specific C-to-U RNA editing at stem-loop substrates in innate immune cells and can restrict Alu retrotransposition by sequestering Alu RNAs in HMM complexes."},"narrative":{"mechanistic_narrative":"APOBEC3G is a cytoplasmically retained single-stranded DNA/RNA cytidine deaminase that functions as an intrinsic restriction factor against HIV-1 and retroelements [PMID:12808466, PMID:12808465, PMID:16999936]. It is built from two zinc-coordinating domains with division of labor: the catalytic C-terminal domain (CD2) carries out C-to-U deamination, while the non-catalytic N-terminal domain (CD1) mediates RNA binding, oligomerization, and virion encapsidation [PMID:15668174, PMID:15721369, PMID:18288108, PMID:25984970]. Packaged into assembling virions through interaction with the nucleocapsid domain of Gag and selective binding of host 7SL RNA [PMID:15159405, PMID:15358144, PMID:17881443], A3G restricts HIV-1 by two genetically separable routes: processive 3'→5' deamination of minus-strand viral cDNA producing lethal G-to-A hypermutation (with edited uracils subsequently targeted by uracil base excision repair) [PMID:12808466, PMID:12808465, PMID:16622407, PMID:29158605], and deaminase-independent impedance of reverse transcription — blocking elongation and strand transfer by competing with RT for ssDNA, directly binding RT, and forming oligomeric roadblocks on the template [PMID:17855362, PMID:17942420, PMID:22301159, PMID:23761443, PMID:28928403]. Its enzymatic state is governed by RNA, which both competitively and allosterically suppresses ssDNA deaminase activity and drives dimer/oligomer dissociation from DNA [PMID:21856286, PMID:26424853]. HIV-1 Vif neutralizes A3G by nucleating a CBF-β–CUL5–ELOB–ELOC–RBX E3 ubiquitin ligase that polyubiquitinates A3G for proteasomal degradation, an interaction in which RNA serves as molecular glue at the Vif–A3G N-terminal-domain interface [PMID:14564014, PMID:14528300, PMID:14528301, PMID:14527406, PMID:22190037, PMID:36754086, PMID:36598981]. Beyond antiviral defense, A3G performs site-specific C-to-U editing of cellular mRNAs at stem-loop substrates under cellular stress and restricts Alu retrotransposition by sequestering Alu RNAs in cytoplasmic high-molecular-mass ribonucleoprotein complexes [PMID:17030807, PMID:27974822, PMID:29230368].","teleology":[{"year":2003,"claim":"Established the molecular basis of A3G antiviral activity: that it is a cytidine deaminase acting on nascent viral DNA, answering how a host factor could mutationally cripple retroviral replication.","evidence":"Retroviral infection and hypermutation analysis of viral DNA","pmids":["12808466","12808465"],"confidence":"High","gaps":["Did not resolve whether deamination is the sole restriction mechanism","Directionality and processivity of editing unaddressed"]},{"year":2003,"claim":"Defined the viral countermeasure: Vif binds A3G and assembles a Cullin5-based E3 ubiquitin ligase to drive its proteasomal degradation and exclude it from virions, explaining Vif's essentiality.","evidence":"Co-IP, ubiquitination/proteasome inhibitor assays, virion fractionation, species-specificity controls","pmids":["14564014","14528300","14528301","14527406","12859895"],"confidence":"High","gaps":["Full ligase composition not yet complete (CBF-β unknown)","Structural basis of Vif–A3G recognition unresolved","Reported translational inhibition of A3G mRNA needed independent mechanistic support"]},{"year":2004,"claim":"Determined how A3G enters virions, showing packaging depends on the Gag nucleocapsid domain and a defined A3G region (aa 104-156), establishing encapsidation as a prerequisite for restriction.","evidence":"Co-IP, VLP fractionation, deletion mutagenesis","pmids":["15159405","15358144"],"confidence":"High","gaps":["RNA dependence of packaging not yet defined","Whether packaging requires oligomerization unknown"]},{"year":2005,"claim":"Resolved the functional architecture of A3G's two domains, dissociating CD1-mediated antiviral/encapsidation function from CD2-mediated catalysis and demonstrating deaminase-independent restriction.","evidence":"Active-site and deletion mutagenesis with infectivity, RNA-binding, encapsidation, and deaminase readouts","pmids":["15668174","15721369"],"confidence":"High","gaps":["Molecular nature of deaminase-independent restriction not defined","Structures of either domain not yet available"]},{"year":2006,"claim":"Characterized the biochemical mode of editing and the resting state of A3G, showing processive 3'→5' scanning on ssDNA and residence in cytoplasmic HMM RNP complexes with Argonautes/P-bodies/stress granules.","evidence":"In vitro processivity assays, TAP-MS, confocal microscopy","pmids":["16622407","17166910","17030807","16999936"],"confidence":"High","gaps":["Functional relevance of P-body/stress-granule localization unclear","How RNA gates catalytic activity in HMM complexes unknown"]},{"year":2007,"claim":"Demonstrated deaminase-independent inhibition of reverse transcription, showing A3G blocks elongation and strand transfer by out-competing RT for ssDNA, with selective 7SL RNA co-packaging supporting virion loading.","evidence":"Endogenous RT assays in cell-free virions, in vitro primer extension, fluorescence anisotropy, single-molecule stretching, encapsidation assays","pmids":["17855362","19057663","17942420","17881443"],"confidence":"High","gaps":["Whether A3G directly contacts RT not yet shown","Relative contribution of editing vs. physical blockade in vivo unquantified"]},{"year":2008,"claim":"Provided the first atomic view of the catalytic domain and identified post-translational and transcriptional regulators, defining the active-site DNA-binding model and PKA/Thr32 phosphorylation that modulates Vif susceptibility.","evidence":"NMR structure with DNA titration, in vitro kinase assays, mutagenesis, transcription factor/reporter studies","pmids":["18288108","18836454","15297452","17517765","16982890"],"confidence":"High","gaps":["N-terminal/Vif-binding domain structure still lacking","Physiological signals controlling these regulatory inputs in vivo unclear"]},{"year":2009,"claim":"Established that A3G oligomerization is RNA-dependent and mapped to CD1 residues (Y124/W127) that double as packaging determinants, linking oligomeric state to encapsidation and Vif translational control.","evidence":"Y2H, Co-IP, crosslinking, homology modeling, mutagenesis, in vitro RNA-binding/translation assays","pmids":["19266078","19910370"],"confidence":"High","gaps":["Stoichiometry of functional oligomers unresolved","How oligomerization toggles catalytic vs. blocking activity unknown"]},{"year":2010,"claim":"Connected oligomeric state to enzymatic behavior and uncovered an additional restriction output, showing CD1 governs processivity and 3'→5' polarity and that A3G impairs integration by generating a 6-bp U5 LTR extension.","evidence":"MALS, AFM, mutagenesis, Southern blot of viral cDNA, integration assays","pmids":["20212048","20219927"],"confidence":"High","gaps":["Integration defect mechanism's in vivo weight unclear","Whether monomer or oligomer is the antiviral unit unresolved"]},{"year":2011,"claim":"Defined RNA as a direct negative regulator of A3G catalysis, showing RNA forms RNP complexes that block ssDNA binding and that CBF-β is an obligate component of the Vif degradation machinery.","evidence":"In vitro deaminase assays with defined RNA, native PAGE, AP-MS, reconstituted in vitro ubiquitination, RNAi rescue","pmids":["21856286","22190037"],"confidence":"High","gaps":["Whether RNA inhibition is purely competitive or allosteric not yet distinguished","Structural role of CBF-β in the ligase unknown"]},{"year":2012,"claim":"Identified a direct A3G–RT interaction (A3G aa 65-132) underlying deaminase-independent inhibition and revealed a nuclear, DNA-repair-associated role of A3G at double-strand breaks.","evidence":"Cell-based Co-IP, deletion analysis, competitive peptide disruption; nuclear fractionation, DSB foci IF, repair assays, AFM","pmids":["22301159","22645179"],"confidence":"Medium","gaps":["RT interaction lacks in vitro reconstitution","Reconciliation of nuclear DSB role with predominantly cytoplasmic localization unresolved"]},{"year":2013,"claim":"Built a dynamic model of A3G action on DNA, showing monomers bind ssDNA rapidly then oligomerize into slow-dissociating roadblocks, and that RNA binding via W94/W127 is specifically required for deaminase-independent restriction.","evidence":"Single-molecule DNA stretching, fluorescence anisotropy, oligomerization mutants, RNA-binding mutants with infectivity/RT/integration readouts; P-body disruption assays","pmids":["24345943","23761443","23926332"],"confidence":"High","gaps":["Direct structural snapshot of the oligomeric roadblock lacking","Quantitative split between editing and roadblocking in primary cells unclear"]},{"year":2015,"claim":"Solved the N-terminal Vif-binding domain structure and dissected mechanisms of RNA-mediated inhibition, mapping distinct ssDNA- and RNA-binding surfaces and the Vif-interacting loops, alongside discovery of A3G-stabilizing factors HDAC6 and ASK1.","evidence":"NMR structure, crosslinking MS, fluorescence anisotropy, native PAGE, Co-IP domain mapping, autophagy/complex-assembly assays","pmids":["25984970","26424853","26105074","25901786"],"confidence":"High","gaps":["Full-length A3G structure still unresolved","In vivo significance of HDAC6/ASK1 regulation in infection uncertain"]},{"year":2016,"claim":"Provided crystallographic detail of the CD1 dimerization interface bound to ssDNA and established A3G as a transcriptome-wide site-specific mRNA C-to-U editor requiring both catalytic domains.","evidence":"X-ray crystallography of CD1 ± ssDNA, mutagenesis, RNA-seq, RNA co-purification","pmids":["27480941","27974822"],"confidence":"High","gaps":["Physiological function of cellular mRNA editing unknown","How CD1 catalytic residues contribute to RNA editing mechanistically unclear"]},{"year":2017,"claim":"Refined substrate selectivity rules and the inhibition-by-oligomerization model, defining the preferred CCCA ssDNA and stem-loop RNA substrates and showing UBER enzymes cleave A3G-edited viral cDNA.","evidence":"Crystallography with Pot1-fusion ssDNA anchoring, single-molecule biophysics, RNA editing substrate mutagenesis, deep sequencing of RT products in T cells, UBER inhibitor assays","pmids":["29596531","28928403","29230368","29158605"],"confidence":"High","gaps":["In vivo balance between hypermutation and UBER-mediated degradation of edited cDNA unquantified","Determinants of RNA vs DNA substrate choice not fully separated"]},{"year":2019,"claim":"Extended A3G's editing biology to physiological cell states and identified a deubiquitinase counter-regulator, showing stress/hypoxia-driven mRNA editing in NK cells and USP49-mediated stabilization of A3G via a Vif/cullin-independent degradation pathway.","evidence":"RNA-seq in primary NK cells with metabolic inhibitors and HIF-1α KO; Co-IP, in vitro deubiquitination, pathway dissection","pmids":["30791937","31397674"],"confidence":"Medium","gaps":["Functional consequence of NK-cell mRNA editing unknown","Identity of the Vif-independent E3 ligase opposed by USP49 unresolved"]},{"year":2020,"claim":"Delivered full-length A3G structures revealing inter-domain packing and a positive electrostatic RNA-binding surface, contextualizing oligomerization and packaging behavior.","evidence":"Cryo-EM and X-ray crystallography of full-length rhesus A3G, mutagenesis, virion packaging assays","pmids":["32005813"],"confidence":"High","gaps":["Conformational changes during catalysis vs. RNA binding not captured","Determinants of packaging beyond the electrostatic surface unclear"]},{"year":2023,"claim":"Resolved the complete Vif degradation complex bound to A3G, demonstrating that RNA acts as molecular glue at the Vif–A3G N-terminal interface while the catalytic domain is poised for ubiquitin transfer, unifying the structural basis of restriction antagonism.","evidence":"Cryo-EM of A3G–Vif–CBF-β–CUL5-RING complex with biochemical binding and mutagenesis, independently confirmed","pmids":["36754086","36598981"],"confidence":"High","gaps":["Mechanism of the ubiquitin-independent Vif repression mode incompletely defined","How this complex assembles on packaged vs. cytoplasmic A3G in cells unclear"]},{"year":null,"claim":"The physiological role of A3G's cellular mRNA editing and its nuclear DNA-repair activity, and how A3G's enzymatic and deaminase-independent restriction modes are quantitatively balanced in vivo, remain unresolved.","evidence":"No single study in the corpus integrates these activities into one quantitative cellular model","pmids":[],"confidence":"Medium","gaps":["Biological purpose of transcriptome-wide C-to-U editing unknown","Relative in vivo contribution of hypermutation vs. physical RT blockade unquantified","Mechanism and physiological trigger of nuclear DSB recruitment unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0,6,9,33]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[0,6,9]},{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[8,13,44,45]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[6,16,22]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,6]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[18]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[10,11,28]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[25]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,2,39]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[33,36,46]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,2,23,37]}],"complexes":["Vif–CBF-β–CUL5–ELOB–ELOC–RBX E3 ubiquitin ligase (substrate)","high-molecular-mass cytoplasmic ribonucleoprotein complex","P-body / stress granule RNP"],"partners":["VIF","CUL5","ELOB","ELOC","RBX1","CBFB","USP49","HDAC6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9HC16","full_name":"DNA dC->dU-editing enzyme APOBEC-3G","aliases":["APOBEC-related cytidine deaminase","APOBEC-related protein","ARCD","APOBEC-related protein 9","ARP-9","CEM-15","CEM15","Deoxycytidine deaminase","A3G"],"length_aa":384,"mass_kda":46.4,"function":"DNA deaminase (cytidine deaminase) which acts as an inhibitor of retrovirus replication and retrotransposon mobility via deaminase-dependent and -independent mechanisms (PubMed:12808465, PubMed:16527742, PubMed:17121840, PubMed:18288108, PubMed:18849968, PubMed:19153609, PubMed:21123384, PubMed:22791714, PubMed:25542899). Exhibits potent antiviral activity against Vif-deficient HIV-1 (PubMed:12167863, PubMed:12859895, PubMed:14557625, PubMed:20219927, PubMed:21835787, PubMed:22807680, PubMed:22915799, PubMed:23097438, PubMed:23152537, PubMed:31397674). After the penetration of retroviral nucleocapsids into target cells of infection and the initiation of reverse transcription, it can induce the conversion of cytosine to uracil in the minus-sense single-strand viral DNA, leading to G-to-A hypermutations in the subsequent plus-strand viral DNA (PubMed:12808465, PubMed:12808466, PubMed:12809610, PubMed:12970355, PubMed:14528300, PubMed:22807680). The resultant detrimental levels of mutations in the proviral genome, along with a deamination-independent mechanism that works prior to the proviral integration, together exert efficient antiretroviral effects in infected target cells (PubMed:12808465, PubMed:12808466, PubMed:12809610, PubMed:12970355, PubMed:14528300). Selectively targets single-stranded DNA and does not deaminate double-stranded DNA or single- or double-stranded RNA (PubMed:12808465, PubMed:12809610, PubMed:12970355, PubMed:14528300). Exhibits antiviral activity also against simian immunodeficiency viruses (SIVs), hepatitis B virus (HBV), equine infectious anemia virus (EIAV), xenotropic MuLV-related virus (XMRV) and simian foamy virus (SFV) (PubMed:15031497, PubMed:16378963, PubMed:18448976, PubMed:19458006, PubMed:20335265). May inhibit the mobility of LTR and non-LTR retrotransposons (PubMed:16527742)","subcellular_location":"Cytoplasm; Nucleus; Cytoplasm, P-body","url":"https://www.uniprot.org/uniprotkb/Q9HC16/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/APOBEC3G","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/APOBEC3G","total_profiled":1310},"omim":[{"mim_id":"612177","title":"RNA, 7SL, CYTOPLASMIC 1; RN7SL1","url":"https://www.omim.org/entry/612177"},{"mim_id":"610976","title":"APOLIPOPROTEIN B mRNA EDITING ENZYME, CATALYTIC POLYPEPTIDE-LIKE 3H; APOBEC3H","url":"https://www.omim.org/entry/610976"},{"mim_id":"609423","title":"HUMAN IMMUNODEFICIENCY VIRUS TYPE 1, SUSCEPTIBILITY TO","url":"https://www.omim.org/entry/609423"},{"mim_id":"608993","title":"APOLIPOPROTEIN B mRNA-EDITING ENZYME, CATALYTIC POLYPEPTIDE-LIKE 3F; APOBEC3F","url":"https://www.omim.org/entry/608993"},{"mim_id":"607790","title":"TET METHYLCYTOSINE DIOXYGENASE 1; TET1","url":"https://www.omim.org/entry/607790"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Nucleoplasm","reliability":"Uncertain"},{"location":"Cytosol","reliability":"Uncertain"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":43.0}],"url":"https://www.proteinatlas.org/search/APOBEC3G"},"hgnc":{"alias_symbol":["CEM15","MDS019","dJ494G10.1","FLJ12740","bK150C2.7"],"prev_symbol":[]},"alphafold":{"accession":"Q9HC16","domains":[{"cath_id":"3.40.140.10","chopping":"9-194","consensus_level":"high","plddt":88.6698,"start":9,"end":194},{"cath_id":"3.40.140.10","chopping":"200-381","consensus_level":"high","plddt":91.313,"start":200,"end":381}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HC16","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HC16-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9HC16-F1-predicted_aligned_error_v6.png","plddt_mean":88.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=APOBEC3G","jax_strain_url":"https://www.jax.org/strain/search?query=APOBEC3G"},"sequence":{"accession":"Q9HC16","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9HC16.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9HC16/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9HC16"}},"corpus_meta":[{"pmid":"12808466","id":"PMC_12808466","title":"Broad antiretroviral defence by human APOBEC3G through lethal editing of nascent reverse transcripts.","date":"2003","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/12808466","citation_count":1238,"is_preprint":false},{"pmid":"14564014","id":"PMC_14564014","title":"Induction of APOBEC3G ubiquitination and degradation by an HIV-1 Vif-Cul5-SCF complex.","date":"2003","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/14564014","citation_count":1008,"is_preprint":false},{"pmid":"12808465","id":"PMC_12808465","title":"The cytidine deaminase CEM15 induces hypermutation in newly synthesized HIV-1 DNA.","date":"2003","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/12808465","citation_count":914,"is_preprint":false},{"pmid":"14528300","id":"PMC_14528300","title":"The antiretroviral enzyme APOBEC3G is degraded by the proteasome in response to HIV-1 Vif.","date":"2003","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/14528300","citation_count":799,"is_preprint":false},{"pmid":"12859895","id":"PMC_12859895","title":"Species-specific exclusion of APOBEC3G from HIV-1 virions by Vif.","date":"2003","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/12859895","citation_count":763,"is_preprint":false},{"pmid":"14528301","id":"PMC_14528301","title":"HIV-1 Vif protein binds the editing enzyme APOBEC3G and induces its degradation.","date":"2003","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/14528301","citation_count":680,"is_preprint":false},{"pmid":"14527406","id":"PMC_14527406","title":"HIV-1 Vif blocks the antiviral activity of APOBEC3G by impairing both its translation and intracellular stability.","date":"2003","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/14527406","citation_count":607,"is_preprint":false},{"pmid":"15668174","id":"PMC_15668174","title":"Antiviral function of APOBEC3G can be dissociated from cytidine deaminase activity.","date":"2005","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/15668174","citation_count":421,"is_preprint":false},{"pmid":"15269786","id":"PMC_15269786","title":"Ancient adaptive evolution of the primate antiviral DNA-editing enzyme APOBEC3G.","date":"2004","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/15269786","citation_count":371,"is_preprint":false},{"pmid":"22190037","id":"PMC_22190037","title":"Vif hijacks CBF-β to degrade APOBEC3G and promote HIV-1 infection.","date":"2011","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/22190037","citation_count":313,"is_preprint":false},{"pmid":"21835787","id":"PMC_21835787","title":"Human and rhesus APOBEC3D, APOBEC3F, APOBEC3G, and APOBEC3H demonstrate a conserved capacity to restrict Vif-deficient HIV-1.","date":"2011","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/21835787","citation_count":297,"is_preprint":false},{"pmid":"14557625","id":"PMC_14557625","title":"The human immunodeficiency virus type 1 Vif protein reduces intracellular expression and inhibits packaging of APOBEC3G (CEM15), a cellular inhibitor of virus infectivity.","date":"2003","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/14557625","citation_count":274,"is_preprint":false},{"pmid":"15721369","id":"PMC_15721369","title":"Complementary function of the two catalytic domains of APOBEC3G.","date":"2005","source":"Virology","url":"https://pubmed.ncbi.nlm.nih.gov/15721369","citation_count":273,"is_preprint":false},{"pmid":"17942420","id":"PMC_17942420","title":"Deaminase-independent inhibition of HIV-1 reverse transcription by APOBEC3G.","date":"2007","source":"Nucleic acids 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APOBEC3G.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15159405","citation_count":217,"is_preprint":false},{"pmid":"17030807","id":"PMC_17030807","title":"High-molecular-mass APOBEC3G complexes restrict Alu retrotransposition.","date":"2006","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/17030807","citation_count":207,"is_preprint":false},{"pmid":"18288108","id":"PMC_18288108","title":"Structure of the DNA deaminase domain of the HIV-1 restriction factor APOBEC3G.","date":"2008","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/18288108","citation_count":185,"is_preprint":false},{"pmid":"15121899","id":"PMC_15121899","title":"APOBEC3G is a single-stranded DNA cytidine deaminase and functions independently of HIV reverse transcriptase.","date":"2004","source":"Nucleic acids 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\"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro and cell-based demonstration of deaminase activity on viral DNA, independently replicated by multiple labs (PMIDs 12808466 and 12808465)\",\n      \"pmids\": [\"12808466\", \"12808465\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"HIV-1 Vif interacts with cellular proteins Cul5, elongins B and C, and Rbx1 to form an SCF-like E3 ubiquitin ligase complex that induces polyubiquitination and proteasomal degradation of APOBEC3G.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, proteasome inhibitor studies\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP identifying the full complex, functional mutagenesis of Vif, replicated across multiple labs (PMIDs 14564014, 14528300, 14528301)\",\n      \"pmids\": [\"14564014\", \"14528300\", \"14528301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"HIV-1 Vif prevents APOBEC3G incorporation into progeny virions and induces its proteasomal degradation via ubiquitination, thereby allowing infection to proceed without viral DNA deamination.\",\n      \"method\": \"Virion fractionation, proteasome inhibitor assays, immunoprecipitation\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct virion incorporation assays and proteasome inhibitor studies, replicated across multiple labs (PMIDs 14528300, 14528301, 14527406)\",\n      \"pmids\": [\"14528300\", \"14528301\", \"14527406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"HIV-1 Vif physically binds APOBEC3G and forms a complex with it; species-specific differences in this interaction explain why HIV-1 Vif does not efficiently complex with mouse APOBEC3G.\",\n      \"method\": \"Co-immunoprecipitation, virion encapsidation assays\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with species-specificity controls, replicated across multiple labs (PMIDs 12859895, 14528301)\",\n      \"pmids\": [\"12859895\", \"14528301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Vif impairs both the translation of APOBEC3G mRNA and accelerates posttranslational degradation of the protein by the 26S proteasome, acting through direct physical interaction with APOBEC3G.\",\n      \"method\": \"Western blot with proteasome inhibitors, pulse-chase analysis, immunoprecipitation, endogenous APOBEC3G-specific antiserum\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal mechanisms demonstrated with specific antiserum against endogenous protein, single lab but multiple methods\",\n      \"pmids\": [\"14527406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"APOBEC3G is recruited to the membrane and packaged into HIV-1 Gag virus-like particles through interaction with the nucleocapsid (NC) domain of Gag; amino acids 104-156 of APOBEC3G are required for this incorporation, and Gag alone (without other viral proteins) is sufficient for packaging.\",\n      \"method\": \"Co-immunoprecipitation, virus-like particle fractionation, deletion mutagenesis\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus deletion mutagenesis mapping, corroborated by independent lab (PMID 15358144)\",\n      \"pmids\": [\"15159405\", \"15358144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"APOBEC3G is a single-stranded DNA cytidine deaminase that deaminates cDNA independently of reverse transcriptase; deamination requires the cDNA to be free of its RNA template (RNase H-dependent exposure of ssDNA).\",\n      \"method\": \"In vitro deaminase assay with baculovirus-derived APOBEC3G, RNase H-deficient RT experiments\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified protein, multiple controls including RNase H-deficient RT\",\n      \"pmids\": [\"15121899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"APOBEC3G antiviral activity can be dissociated from cytidine deaminase activity: the N-terminal domain (CD1) can confer antiviral function without DNA mutator activity, whereas the C-terminal domain (CD2) is essential for deaminase activity. Only the C-terminal catalytic motif is required for DNA hypermutation.\",\n      \"method\": \"Site-directed mutagenesis of catalytic motifs, infectivity assays, deaminase activity assays\",\n      \"journal\": \"Current Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site mutagenesis of both catalytic domains with functional readouts for both deaminase and antiviral activity\",\n      \"pmids\": [\"15668174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"APOBEC3G's N-terminal domain (CD1) mediates RNA binding and virion encapsidation through zinc-coordination residues and conserved aromatic residues, while the C-terminal domain (CD2) mediates cytidine deaminase activity; the two domains have complementary but non-redundant functions.\",\n      \"method\": \"Deletion and point mutagenesis, RNA binding assays, virion encapsidation assays\",\n      \"journal\": \"Virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic mutagenesis of both domains with multiple functional readouts (RNA binding, encapsidation, deaminase activity)\",\n      \"pmids\": [\"15721369\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"APOBEC3G acts processively on single-stranded DNA in the 3'→5' direction by a combination of jumping and sliding mechanisms, without requiring a nucleotide cofactor, explaining the G-to-A mutational gradient observed in viral DNA.\",\n      \"method\": \"In vitro biochemical deamination assays, processivity measurements on ssDNA substrates\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous in vitro biochemical reconstitution with multiple substrate configurations, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"16622407\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"APOBEC3G localizes to P bodies and stress granules as part of high-molecular-weight ribonucleoprotein (RNP) complexes; it associates with Argonaute 1 and Argonaute 2 in an RNase-resistant manner, and redistributes to stress granules upon cellular stress.\",\n      \"method\": \"Tandem affinity purification/mass spectrometry, confocal microscopy, RNase treatment co-immunoprecipitation\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — TAP-MS plus confocal microscopy showing localization with functional stress-response redistribution, two orthogonal methods\",\n      \"pmids\": [\"17166910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"High-molecular-mass (HMM) APOBEC3G complexes, which contain Staufen-containing RNA-transporting granules and Ro RNP complexes loaded with Alu and small Y RNAs, restrict Alu retrotransposition by sequestering Alu RNAs in cytoplasmic HMM complexes rather than by inhibiting L1 reverse transcriptase function.\",\n      \"method\": \"Tandem affinity purification/MS, Alu retrotransposition reporter assay, RNA analysis\",\n      \"journal\": \"PNAS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — TAP-MS identification of complex components plus functional retrotransposition assay distinguishing mechanism (sequestration vs. L1 inhibition)\",\n      \"pmids\": [\"17030807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"APOBEC3G inhibits HIV-1 minus- and plus-strand DNA transfer steps during reverse transcription independently of its editing activity; this inhibition correlates with its ability to prevent RNase H degradation of the RNA template.\",\n      \"method\": \"In vivo viral cDNA intermediate analysis, in vitro strand transfer assay\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — combined in vivo and in vitro assays with deaminase-dead mutant controls, single lab\",\n      \"pmids\": [\"17855362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"7SL RNA selectively interacts with APOBEC3G and is preferentially packaged into HIV-1 particles via the nucleocapsid domain of Gag; APOBEC3G mutants with reduced 7SL RNA binding are packaged poorly and have impaired antiviral activity.\",\n      \"method\": \"RNA-binding assays, virion encapsidation assays, SRP19 overexpression to competitively reduce 7SL RNA\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional co-packaging assays with mutants and competitive inhibition, single lab\",\n      \"pmids\": [\"17881443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"APOBEC3G inhibits HIV-1 reverse transcription elongation in a deaminase-independent manner; in cell-free virions, A3G impedes elongation of cDNA products without requiring target cell factors.\",\n      \"method\": \"Endogenous reverse transcriptase assay in cell-free virions\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-free endogenous RT assay directly measuring elongation, single lab\",\n      \"pmids\": [\"19057663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"APOBEC3G inhibits RT-catalyzed DNA elongation reactions in a deaminase-independent manner by competing with RT for ssDNA binding; NC has faster nucleic acid association/dissociation kinetics than A3G, while RT binds ssDNA with much lower affinity than A3G.\",\n      \"method\": \"In vitro primer extension assays, fluorescence anisotropy, single-molecule DNA stretching\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal in vitro methods (primer extension, fluorescence anisotropy, single-molecule), rigorous kinetic analysis\",\n      \"pmids\": [\"17942420\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The solution structure of the APOBEC3G catalytic (C-terminal) domain reveals five alpha-helices arranged over a hydrophobic beta-strand platform with a zinc-coordinating active site; NMR DNA titration and mutagenesis define a DNA-binding model with positively charged residues positioning the target cytosine for catalysis.\",\n      \"method\": \"NMR structure determination, DNA titration NMR, computational modelling, E. coli-based activity assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure with functional validation by mutagenesis and activity assays, multiple orthogonal methods in single study\",\n      \"pmids\": [\"18288108\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Protein kinase A (PKA) binds and phosphorylates APOBEC3G at Thr32 in vitro and in vivo; this phosphorylation reduces A3G binding to Vif, diminishes Vif-induced ubiquitination and degradation, and promotes antiviral activity.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation, mutagenesis, structural modeling\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro kinase assay plus cell-based Co-IP and mutagenesis, single lab with two orthogonal methods\",\n      \"pmids\": [\"18836454\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"APOBEC3G is exclusively retained in the cytoplasm and does not undergo nucleo-cytoplasmic shuttling; this cytoplasmic retention requires both the N- and C-terminal regions of the protein.\",\n      \"method\": \"Live-cell imaging, subcellular fractionation, heterokaryon assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiments with multiple protein regions tested, single lab\",\n      \"pmids\": [\"16999936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"APOBEC3G oligomerization is RNA-dependent and requires tyrosine-124 and tryptophan-127 in the N-terminal CDA domain; these oligomerization-mediating residues also coincide with virion packaging determinants. Arginine residues at positions 24, 30, and 136 in a positively charged pocket promote RNA-dependent oligomerization and virion packaging.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, chemical crosslinking, homology modeling, mutational analysis\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — three orthogonal methods (Y2H, Co-IP, crosslinking) plus structural modeling and mutagenesis, single lab\",\n      \"pmids\": [\"19266078\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"HIV-1 Vif directly binds to APOBEC3G mRNA (with higher affinity for the 3'UTR) and inhibits its translation by two mechanisms: a time-independent process requiring the 5'UTR and an additional UTR-independent process.\",\n      \"method\": \"Filter binding assays, fluorescence titration, RNase footprinting, in vitro translation assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro binding and translation assays with defined RNA regions, single lab\",\n      \"pmids\": [\"19910370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"APOBEC3G inhibits HIV-1 DNA integration by generating a 6-bp extension at the viral U5 end of the 3'-LTR (a poor substrate for integration), dependent on a functional C-terminal catalytic domain; this mechanism is distinct from that of APOBEC3F.\",\n      \"method\": \"Southern blot analysis of viral cDNA processing, integration assays, mutational analysis\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Southern blot mapping of specific DNA end-processing defects with catalytic domain mutants, single lab\",\n      \"pmids\": [\"20219927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"APOBEC3G exists as monomers, dimers, tetramers, and higher-order oligomers; the CD1 domain is essential for both processivity and 3'→5' deamination polarity. A CD1-CD1 dimer interface mutant (F126A/W127A) predominantly converts A3G to a monomer that retains ssDNA binding, Alu RNA binding, and processive deaminase activity.\",\n      \"method\": \"Multiangle light scattering, atomic force microscopy, mutagenesis, deaminase activity assays\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal structural/biochemical methods (MALS, AFM) plus mutagenesis and functional assays, single lab\",\n      \"pmids\": [\"20212048\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Vif additionally recruits the transcription cofactor CBF-β to the Vif-CUL5-ELOC-ELOB-RBX ubiquitin ligase complex; CBF-β is required for Vif-mediated APOBEC3G degradation and a reconstituted six-protein assembly elicits specific polyubiquitination of APOBEC3G but not APOBEC3A.\",\n      \"method\": \"Affinity tag/purification mass spectrometry, RNA knockdown, genetic complementation, reconstituted in vitro ubiquitination assay\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — AP-MS discovery plus reconstituted in vitro ubiquitination assay plus RNAi rescue, multiple orthogonal methods, single lab with rigorous controls\",\n      \"pmids\": [\"22190037\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"APOBEC3G directly interacts with HIV-1 reverse transcriptase (RT); the RT-binding region of A3G maps to amino acids 65-132. This interaction disrupts RT function and plays an important role in A3G's deaminase-independent inhibition of reverse transcription.\",\n      \"method\": \"Cell-based co-immunoprecipitation, deletion analysis, overexpression of binding-domain peptide to competitively disrupt interaction\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus competitive disruption experiment, single lab, no in vitro reconstitution\",\n      \"pmids\": [\"22301159\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"APOBEC3G accumulates transiently in the nucleus in response to ionizing radiation, is recruited to DNA double-strand break (DSB) repair foci, and promotes DSB repair in a deaminase-dependent manner; AFM shows that A3G multimers associate with ssDNA termini at DSBs.\",\n      \"method\": \"Nuclear fractionation, immunofluorescence recruitment to DSB foci, siRNA knockdown with DSB repair assay, reporter cassette, atomic force microscopy\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization to DSB foci plus functional rescue experiment and AFM, single lab\",\n      \"pmids\": [\"22645179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"APOBEC3G initially binds ssDNA with rapid on-off rates and subsequently converts to a slowly dissociating mode through oligomerization; an oligomerization-deficient mutant does not exhibit the slow off rate, suggesting catalytically active monomers/dimers oligomerize on the viral genome to inhibit reverse transcription.\",\n      \"method\": \"Single-molecule DNA stretching, fluorescence anisotropy, oligomerization mutant analysis\",\n      \"journal\": \"Nature chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — single-molecule biophysics plus fluorescence anisotropy with oligomerization-deficient mutant, multiple orthogonal methods\",\n      \"pmids\": [\"24345943\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"RNA binding by APOBEC3G (via tryptophan residues W94 and W127 in the N-terminal domain) is specifically required for deamination-independent restriction of retroviruses, including inhibition of late reverse transcript accumulation and prevention of proviral DNA integration; deaminase activity does not significantly contribute to restriction of these processes.\",\n      \"method\": \"Mutagenesis of RNA-binding residues, retroviral infectivity assays, RT product quantification, integration assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional mutagenesis with multiple downstream readouts, single lab\",\n      \"pmids\": [\"23761443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"APOBEC3G and P-body localization to processing bodies is not required for virion incorporation or antiviral activity; sucrose gradient analysis shows the majority of A3G is in high-molecular-mass RNA-protein complexes distinct from canonical P-body markers.\",\n      \"method\": \"DDX6 knockdown to disrupt P bodies, SRP19 overexpression to deplete A3G from P bodies, sucrose gradient sedimentation\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — P-body disruption by two independent methods with virion incorporation readout, single lab\",\n      \"pmids\": [\"23926332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"NMR structure of the APOBEC3G N-terminal (Vif-binding) domain reveals a smaller zinc-coordinating pocket and altered helical packing compared to the catalytic domain; the Vif-interacting surface is formed by loops α1-β1, β2-α2, and β4-α4, identified by mutagenesis and biochemical binding experiments.\",\n      \"method\": \"NMR structure determination (evolution- and structure-guided solubilizing mutations), mutagenesis, biochemical binding assays\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — NMR structure with functional mutagenesis validation of Vif-binding surface, multiple orthogonal methods\",\n      \"pmids\": [\"25984970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"HDAC6 directly interacts with APOBEC3G through its C-terminal BUZ domain and co-distributes along microtubules; HDAC6 also interacts with Vif and promotes its autophagic degradation (requiring HDAC6 deacetylase activity), thereby stabilizing A3G and increasing its incorporation into virions.\",\n      \"method\": \"Co-immunoprecipitation, domain mapping, autophagy inhibitor assays, virion fractionation\",\n      \"journal\": \"Retrovirology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP domain mapping plus functional autophagy assays, single lab\",\n      \"pmids\": [\"26105074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ASK1 (apoptosis signal-regulating kinase 1) binds the BC-box of Vif, disrupting assembly of the Vif-ubiquitin ligase complex, thereby stabilizing A3G and promoting its incorporation into viral particles; AZT treatment induces ASK1 expression, restoring A3G antiviral activity.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitin ligase complex assembly assays, virion fractionation, viral infectivity assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional complex disruption assays, single lab\",\n      \"pmids\": [\"25901786\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Crystal structure of a primate A3G N-terminal domain (CD1) alone and in complex with ssDNA shows the dimerization interface and reveals conformational changes in loops around the zinc-coordinated center upon DNA binding; the CD1 dimerization interface is important for oligomerization, nucleic acid binding, and Vif-mediated degradation.\",\n      \"method\": \"X-ray crystallography, mutagenesis, functional assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with ssDNA-bound and apo forms plus mutagenesis validation of functional relevance, single lab\",\n      \"pmids\": [\"27480941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"APOBEC3G causes site-specific C-to-U editing of mRNAs from over 600 genes, requiring conserved catalytic residues in both N-terminal and C-terminal cytidine deaminase domains; APOBEC3G co-purifies with highly edited mRNA substrates.\",\n      \"method\": \"Transcriptome-wide RNA-seq, active-site mutagenesis of both catalytic domains, RNA co-purification\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transcriptome-wide sequencing plus mutagenesis of both catalytic domains, single lab, novel finding\",\n      \"pmids\": [\"27974822\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Deep sequencing of HIV-1 reverse transcripts in infected T cells demonstrates that A3G inhibits reverse transcription in a site- and sequence-independent manner that requires direct interaction with reverse transcriptase; cellular uracil base excision repair (UBER) enzymes target and cleave A3G-edited uridine-containing viral cDNA.\",\n      \"method\": \"Deep sequencing of nascent reverse transcription products, A3G-RT interaction studies, UBER inhibitor assays\",\n      \"journal\": \"Nature microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — novel deep-sequencing strategy in primary T cells plus mechanistic A3G-RT interaction and UBER pathway, multiple orthogonal findings in one study\",\n      \"pmids\": [\"29158605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"APOBEC3G first binds ssDNA as a catalytically active monomer, then forms N-terminal domain-mediated dimers whose dissociation from DNA is reduced and deaminase activity is inhibited; this dimerization-to-inactivation mechanism may create enzymatically deficient roadblocks that inhibit reverse transcription.\",\n      \"method\": \"Single-molecule DNA stretching, fluorescence assays with wild-type and oligomerization-deficient A3G mutants\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — single-molecule biophysics with oligomerization mutants, single lab\",\n      \"pmids\": [\"28928403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"APOBEC3G induces widespread site-specific C-to-U mRNA editing in natural killer cells and lymphoma cell lines under conditions of cellular crowding and hypoxia (mimicked by mitochondrial respiration inhibition), independently of HIF-1α; this editing is enriched for genes involved in mRNA translation and ribosome function.\",\n      \"method\": \"RNA-seq in primary NK cells, mitochondrial inhibitors, HIF-1α knockout controls, metabolic assays\",\n      \"journal\": \"Genome biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transcriptome-wide RNA-seq in primary cells with mechanistic controls (inhibitors, KO), single lab\",\n      \"pmids\": [\"30791937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP49 directly interacts with APOBEC3G and efficiently removes ubiquitin from it, stabilizing A3G protein expression and enhancing its anti-HIV-1 activity; A3G degradation also occurs via a Vif- and cullin-ring-independent pathway that USP49 counteracts.\",\n      \"method\": \"Co-immunoprecipitation, in vitro deubiquitination assay, proteasome pathway dissection, clinical sample correlation\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional deubiquitination assays with pathway mutants, single lab\",\n      \"pmids\": [\"31397674\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Full-length rhesus macaque A3G cryo-EM/crystal structures reveal different inter-domain packing through a short linker and refolding of CD2; A3G dimerization generates a surface with intensified positive electrostatic potential for RNA binding and dimer stabilization, though mutating this surface does not abolish virion packaging.\",\n      \"method\": \"Cryo-EM and X-ray crystallography of full-length A3G, mutagenesis, virion packaging assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — full-length protein structures by two methods plus functional mutagenesis, single lab\",\n      \"pmids\": [\"32005813\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Cryo-EM structure of human APOBEC3G bound to HIV-1 Vif in complex with CBF-β and the CUL5-RING E3 ubiquitin ligase reveals that RNA acts as molecular glue for the Vif-A3G interaction; Vif makes contact primarily through A3G's non-catalytic N-terminal domain while the catalytic domain is positioned for ubiquitin transfer. Vif can repress A3G by both ubiquitin-dependent and ubiquitin-independent mechanisms.\",\n      \"method\": \"Cryo-electron microscopy structure determination, biochemical binding assays, mutagenesis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure of full complex with independent confirmation from a second cryo-EM study (PMID 36598981), multiple mechanistic insights validated by mutagenesis\",\n      \"pmids\": [\"36754086\", \"36598981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Transcription of APOBEC3G in human T lymphocytes is controlled by the PKCα/βI–MEK–ERK protein kinase cascade; PKCα/βI/MEK/ERK pathway inhibitors reduce both basal and induced APOBEC3G mRNA/protein levels, and this pathway is activated by phorbol myristate acetate.\",\n      \"method\": \"Pharmacological inhibitor studies, luciferase reporter assays, RT-PCR and western blot\",\n      \"journal\": \"Journal of Biological Chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple inhibitors at distinct pathway steps converging on the same outcome, single lab\",\n      \"pmids\": [\"15297452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Basal transcription of the APOBEC3G gene is regulated by transcription factors Sp1 and Sp3 through a GC-box element at position -87/-78 relative to the major transcriptional start site; mutation of this GC-box abolishes promoter activity.\",\n      \"method\": \"Luciferase reporter assays, EMSA, chromatin immunoprecipitation (ChIP), 5' RACE\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA plus ChIP plus reporter assay with GC-box mutation, single lab\",\n      \"pmids\": [\"17517765\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"IFN-α induces APOBEC3G expression in liver cells and macrophages but not in T cells or epithelial cells; this induction is STAT1-independent but STAT2-dependent in liver cells, revealing a non-canonical IFN-α signaling pathway for A3G regulation.\",\n      \"method\": \"Cytokine treatment, pathway inhibitors (Rottlerin), STAT1-deficient cells, western blot/RT-PCR\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — STAT1-null cells plus specific inhibitor corroborating STAT2-dependence, single lab\",\n      \"pmids\": [\"16982890\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The prolyl isomerase Pin1 interacts with APOBEC3G and reduces its expression and incorporation into HIV-1 virions; HIV-1 infection modulates Pin1 phosphorylation state, enhancing its ability to decrease A3G activity.\",\n      \"method\": \"Co-immunoprecipitation, virion incorporation assays, HIV infection modulation of Pin1\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP identification plus functional readout, single lab, limited mechanistic follow-up\",\n      \"pmids\": [\"18684817\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"RNA directly suppresses APOBEC3G ssDNA deaminase activity in a concentration-dependent manner; RNA forms RNP complexes with A3G that prevent ssDNA substrates from binding; RNAs as short as 25 nt and of diverse sequences are effective inhibitors.\",\n      \"method\": \"In vitro deaminase assay with defined RNA concentrations, native PAGE gel-shift analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified components plus native PAGE showing competitive displacement of ssDNA by RNA\",\n      \"pmids\": [\"21856286\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"RNA stochastically dissociates APOBEC3G dimers and higher-order oligomers from ssDNA; mass spectrometry cross-linking maps distinct A3G peptide surfaces for ssDNA binding (aa 181-194, 314-320, 345-374) versus RNA binding (same surfaces plus additional N-terminal peptides aa 15-29, 41-52, 83-99), suggesting RNA inhibition occurs through both competitive and allosteric mechanisms.\",\n      \"method\": \"Native PAGE, fluorescence anisotropy, cross-linking mass spectrometry peptide mapping\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cross-linking MS plus fluorescence anisotropy plus native PAGE, multiple orthogonal methods in single study\",\n      \"pmids\": [\"26424853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Both APOBEC3A and APOBEC3G prefer RNA substrates with a stem-loop structure where the reactive cytidine is at the 3'-end of the loop; loop size, nucleotides 5' of the target C, and stem stability all influence editing efficiency.\",\n      \"method\": \"Mutagenesis of endogenous RNA substrates, RNA editing assays\",\n      \"journal\": \"PeerJ\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic mutagenesis of natural RNA substrates with functional editing assays, single lab\",\n      \"pmids\": [\"29230368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structure of APOBEC3G catalytic domain in complex with ssDNA (via Pot1-fusion anchoring strategy) reveals a unique conformation of catalytic-site loops; nucleotide-binding pockets at the -1 and active-site positions influence each other in selecting the preferred CCCA substrate sequence.\",\n      \"method\": \"X-ray crystallography with Pot1-fusion strategy, biochemical deaminase assays, HIV infectivity assays\",\n      \"journal\": \"PLoS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure plus biochemical and virological validation, single lab\",\n      \"pmids\": [\"29596531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"APOBEC3G-mediated C-to-U mRNA editing requires stem-loop RNA secondary structure with the target cytidine at the 3'-end of the loop, and APOBEC3G edits sites largely distinct from those targeted by APOBEC3A.\",\n      \"method\": \"Transcriptome RNA-seq, mutagenesis of RNA substrates\",\n      \"journal\": \"PeerJ\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — comparative RNA-seq plus substrate mutagenesis, single lab\",\n      \"pmids\": [\"29230368\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"APOBEC3G is a cytoplasmic single-stranded DNA/RNA cytidine deaminase that is packaged into HIV-1 virions (via RNA-dependent oligomerization and interaction with Gag nucleocapsid), where it restricts HIV-1 replication through two main mechanisms: (1) processive 3'→5' deamination of minus-strand viral cDNA causing lethal G-to-A hypermutation, and (2) deaminase-independent inhibition of reverse transcriptase elongation and strand-transfer steps through direct RT interaction and RNA-mediated roadblocking; its activity is regulated by molecular state (low-molecular-mass active form vs. high-molecular-mass RNA-bound inactive HMM complexes), by PKA phosphorylation at Thr32, by Sp1/Sp3-driven basal transcription and PKCα/MEK/ERK-driven inducible transcription, and by the deubiquitinase USP49; HIV-1 Vif counteracts A3G by recruiting a CBF-β–CUL5–ELOB–ELOC–RBX E3 ubiquitin ligase complex (structure resolved by cryo-EM) that polyubiquitinates A3G for proteasomal degradation, with RNA serving as molecular glue for the Vif–A3G interface; additionally, A3G performs site-specific C-to-U RNA editing at stem-loop substrates in innate immune cells and can restrict Alu retrotransposition by sequestering Alu RNAs in HMM complexes.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"APOBEC3G is a cytoplasmically retained single-stranded DNA/RNA cytidine deaminase that functions as an intrinsic restriction factor against HIV-1 and retroelements [#0, #18]. It is built from two zinc-coordinating domains with division of labor: the catalytic C-terminal domain (CD2) carries out C-to-U deamination, while the non-catalytic N-terminal domain (CD1) mediates RNA binding, oligomerization, and virion encapsidation [#7, #8, #16, #29]. Packaged into assembling virions through interaction with the nucleocapsid domain of Gag and selective binding of host 7SL RNA [#5, #13], A3G restricts HIV-1 by two genetically separable routes: processive 3'\\u21925' deamination of minus-strand viral cDNA producing lethal G-to-A hypermutation (with edited uracils subsequently targeted by uracil base excision repair) [#0, #9, #34], and deaminase-independent impedance of reverse transcription \\u2014 blocking elongation and strand transfer by competing with RT for ssDNA, directly binding RT, and forming oligomeric roadblocks on the template [#12, #15, #24, #27, #35]. Its enzymatic state is governed by RNA, which both competitively and allosterically suppresses ssDNA deaminase activity and drives dimer/oligomer dissociation from DNA [#44, #45]. HIV-1 Vif neutralizes A3G by nucleating a CBF-\\u03b2\\u2013CUL5\\u2013ELOB\\u2013ELOC\\u2013RBX E3 ubiquitin ligase that polyubiquitinates A3G for proteasomal degradation, an interaction in which RNA serves as molecular glue at the Vif\\u2013A3G N-terminal-domain interface [#1, #2, #23, #39]. Beyond antiviral defense, A3G performs site-specific C-to-U editing of cellular mRNAs at stem-loop substrates under cellular stress and restricts Alu retrotransposition by sequestering Alu RNAs in cytoplasmic high-molecular-mass ribonucleoprotein complexes [#11, #33, #46].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established the molecular basis of A3G antiviral activity: that it is a cytidine deaminase acting on nascent viral DNA, answering how a host factor could mutationally cripple retroviral replication.\",\n      \"evidence\": \"Retroviral infection and hypermutation analysis of viral DNA\",\n      \"pmids\": [\"12808466\", \"12808465\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether deamination is the sole restriction mechanism\", \"Directionality and processivity of editing unaddressed\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defined the viral countermeasure: Vif binds A3G and assembles a Cullin5-based E3 ubiquitin ligase to drive its proteasomal degradation and exclude it from virions, explaining Vif's essentiality.\",\n      \"evidence\": \"Co-IP, ubiquitination/proteasome inhibitor assays, virion fractionation, species-specificity controls\",\n      \"pmids\": [\"14564014\", \"14528300\", \"14528301\", \"14527406\", \"12859895\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full ligase composition not yet complete (CBF-\\u03b2 unknown)\", \"Structural basis of Vif\\u2013A3G recognition unresolved\", \"Reported translational inhibition of A3G mRNA needed independent mechanistic support\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Determined how A3G enters virions, showing packaging depends on the Gag nucleocapsid domain and a defined A3G region (aa 104-156), establishing encapsidation as a prerequisite for restriction.\",\n      \"evidence\": \"Co-IP, VLP fractionation, deletion mutagenesis\",\n      \"pmids\": [\"15159405\", \"15358144\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RNA dependence of packaging not yet defined\", \"Whether packaging requires oligomerization unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Resolved the functional architecture of A3G's two domains, dissociating CD1-mediated antiviral/encapsidation function from CD2-mediated catalysis and demonstrating deaminase-independent restriction.\",\n      \"evidence\": \"Active-site and deletion mutagenesis with infectivity, RNA-binding, encapsidation, and deaminase readouts\",\n      \"pmids\": [\"15668174\", \"15721369\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular nature of deaminase-independent restriction not defined\", \"Structures of either domain not yet available\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Characterized the biochemical mode of editing and the resting state of A3G, showing processive 3'\\u21925' scanning on ssDNA and residence in cytoplasmic HMM RNP complexes with Argonautes/P-bodies/stress granules.\",\n      \"evidence\": \"In vitro processivity assays, TAP-MS, confocal microscopy\",\n      \"pmids\": [\"16622407\", \"17166910\", \"17030807\", \"16999936\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional relevance of P-body/stress-granule localization unclear\", \"How RNA gates catalytic activity in HMM complexes unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated deaminase-independent inhibition of reverse transcription, showing A3G blocks elongation and strand transfer by out-competing RT for ssDNA, with selective 7SL RNA co-packaging supporting virion loading.\",\n      \"evidence\": \"Endogenous RT assays in cell-free virions, in vitro primer extension, fluorescence anisotropy, single-molecule stretching, encapsidation assays\",\n      \"pmids\": [\"17855362\", \"19057663\", \"17942420\", \"17881443\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether A3G directly contacts RT not yet shown\", \"Relative contribution of editing vs. physical blockade in vivo unquantified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Provided the first atomic view of the catalytic domain and identified post-translational and transcriptional regulators, defining the active-site DNA-binding model and PKA/Thr32 phosphorylation that modulates Vif susceptibility.\",\n      \"evidence\": \"NMR structure with DNA titration, in vitro kinase assays, mutagenesis, transcription factor/reporter studies\",\n      \"pmids\": [\"18288108\", \"18836454\", \"15297452\", \"17517765\", \"16982890\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"N-terminal/Vif-binding domain structure still lacking\", \"Physiological signals controlling these regulatory inputs in vivo unclear\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Established that A3G oligomerization is RNA-dependent and mapped to CD1 residues (Y124/W127) that double as packaging determinants, linking oligomeric state to encapsidation and Vif translational control.\",\n      \"evidence\": \"Y2H, Co-IP, crosslinking, homology modeling, mutagenesis, in vitro RNA-binding/translation assays\",\n      \"pmids\": [\"19266078\", \"19910370\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of functional oligomers unresolved\", \"How oligomerization toggles catalytic vs. blocking activity unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Connected oligomeric state to enzymatic behavior and uncovered an additional restriction output, showing CD1 governs processivity and 3'\\u21925' polarity and that A3G impairs integration by generating a 6-bp U5 LTR extension.\",\n      \"evidence\": \"MALS, AFM, mutagenesis, Southern blot of viral cDNA, integration assays\",\n      \"pmids\": [\"20212048\", \"20219927\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Integration defect mechanism's in vivo weight unclear\", \"Whether monomer or oligomer is the antiviral unit unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined RNA as a direct negative regulator of A3G catalysis, showing RNA forms RNP complexes that block ssDNA binding and that CBF-\\u03b2 is an obligate component of the Vif degradation machinery.\",\n      \"evidence\": \"In vitro deaminase assays with defined RNA, native PAGE, AP-MS, reconstituted in vitro ubiquitination, RNAi rescue\",\n      \"pmids\": [\"21856286\", \"22190037\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RNA inhibition is purely competitive or allosteric not yet distinguished\", \"Structural role of CBF-\\u03b2 in the ligase unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified a direct A3G\\u2013RT interaction (A3G aa 65-132) underlying deaminase-independent inhibition and revealed a nuclear, DNA-repair-associated role of A3G at double-strand breaks.\",\n      \"evidence\": \"Cell-based Co-IP, deletion analysis, competitive peptide disruption; nuclear fractionation, DSB foci IF, repair assays, AFM\",\n      \"pmids\": [\"22301159\", \"22645179\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"RT interaction lacks in vitro reconstitution\", \"Reconciliation of nuclear DSB role with predominantly cytoplasmic localization unresolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Built a dynamic model of A3G action on DNA, showing monomers bind ssDNA rapidly then oligomerize into slow-dissociating roadblocks, and that RNA binding via W94/W127 is specifically required for deaminase-independent restriction.\",\n      \"evidence\": \"Single-molecule DNA stretching, fluorescence anisotropy, oligomerization mutants, RNA-binding mutants with infectivity/RT/integration readouts; P-body disruption assays\",\n      \"pmids\": [\"24345943\", \"23761443\", \"23926332\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct structural snapshot of the oligomeric roadblock lacking\", \"Quantitative split between editing and roadblocking in primary cells unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Solved the N-terminal Vif-binding domain structure and dissected mechanisms of RNA-mediated inhibition, mapping distinct ssDNA- and RNA-binding surfaces and the Vif-interacting loops, alongside discovery of A3G-stabilizing factors HDAC6 and ASK1.\",\n      \"evidence\": \"NMR structure, crosslinking MS, fluorescence anisotropy, native PAGE, Co-IP domain mapping, autophagy/complex-assembly assays\",\n      \"pmids\": [\"25984970\", \"26424853\", \"26105074\", \"25901786\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length A3G structure still unresolved\", \"In vivo significance of HDAC6/ASK1 regulation in infection uncertain\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Provided crystallographic detail of the CD1 dimerization interface bound to ssDNA and established A3G as a transcriptome-wide site-specific mRNA C-to-U editor requiring both catalytic domains.\",\n      \"evidence\": \"X-ray crystallography of CD1 \\u00b1 ssDNA, mutagenesis, RNA-seq, RNA co-purification\",\n      \"pmids\": [\"27480941\", \"27974822\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological function of cellular mRNA editing unknown\", \"How CD1 catalytic residues contribute to RNA editing mechanistically unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Refined substrate selectivity rules and the inhibition-by-oligomerization model, defining the preferred CCCA ssDNA and stem-loop RNA substrates and showing UBER enzymes cleave A3G-edited viral cDNA.\",\n      \"evidence\": \"Crystallography with Pot1-fusion ssDNA anchoring, single-molecule biophysics, RNA editing substrate mutagenesis, deep sequencing of RT products in T cells, UBER inhibitor assays\",\n      \"pmids\": [\"29596531\", \"28928403\", \"29230368\", \"29158605\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo balance between hypermutation and UBER-mediated degradation of edited cDNA unquantified\", \"Determinants of RNA vs DNA substrate choice not fully separated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extended A3G's editing biology to physiological cell states and identified a deubiquitinase counter-regulator, showing stress/hypoxia-driven mRNA editing in NK cells and USP49-mediated stabilization of A3G via a Vif/cullin-independent degradation pathway.\",\n      \"evidence\": \"RNA-seq in primary NK cells with metabolic inhibitors and HIF-1\\u03b1 KO; Co-IP, in vitro deubiquitination, pathway dissection\",\n      \"pmids\": [\"30791937\", \"31397674\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of NK-cell mRNA editing unknown\", \"Identity of the Vif-independent E3 ligase opposed by USP49 unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Delivered full-length A3G structures revealing inter-domain packing and a positive electrostatic RNA-binding surface, contextualizing oligomerization and packaging behavior.\",\n      \"evidence\": \"Cryo-EM and X-ray crystallography of full-length rhesus A3G, mutagenesis, virion packaging assays\",\n      \"pmids\": [\"32005813\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conformational changes during catalysis vs. RNA binding not captured\", \"Determinants of packaging beyond the electrostatic surface unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved the complete Vif degradation complex bound to A3G, demonstrating that RNA acts as molecular glue at the Vif\\u2013A3G N-terminal interface while the catalytic domain is poised for ubiquitin transfer, unifying the structural basis of restriction antagonism.\",\n      \"evidence\": \"Cryo-EM of A3G\\u2013Vif\\u2013CBF-\\u03b2\\u2013CUL5-RING complex with biochemical binding and mutagenesis, independently confirmed\",\n      \"pmids\": [\"36754086\", \"36598981\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of the ubiquitin-independent Vif repression mode incompletely defined\", \"How this complex assembles on packaged vs. cytoplasmic A3G in cells unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological role of A3G's cellular mRNA editing and its nuclear DNA-repair activity, and how A3G's enzymatic and deaminase-independent restriction modes are quantitatively balanced in vivo, remain unresolved.\",\n      \"evidence\": \"No single study in the corpus integrates these activities into one quantitative cellular model\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biological purpose of transcriptome-wide C-to-U editing unknown\", \"Relative in vivo contribution of hypermutation vs. physical RT blockade unquantified\", \"Mechanism and physiological trigger of nuclear DSB recruitment unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0, 6, 9, 33]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [0, 6, 9]},\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [8, 13, 44, 45]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [6, 16, 22]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [10, 11, 28]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [25]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 2, 39]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [33, 36, 46]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 2, 23, 37]}\n    ],\n    \"complexes\": [\n      \"Vif\\u2013CBF-\\u03b2\\u2013CUL5\\u2013ELOB\\u2013ELOC\\u2013RBX E3 ubiquitin ligase (substrate)\",\n      \"high-molecular-mass cytoplasmic ribonucleoprotein complex\",\n      \"P-body / stress granule RNP\"\n    ],\n    \"partners\": [\n      \"VIF\",\n      \"CUL5\",\n      \"ELOB\",\n      \"ELOC\",\n      \"RBX1\",\n      \"CBFB\",\n      \"USP49\",\n      \"HDAC6\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}