{"gene":"GMEB2","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":1998,"finding":"GMEB-2 (67-kDa protein) was cloned and shown to bind GME DNA in gel shift assays; binding to GME DNA increased markedly after mixing with GMEB-1, forming a heteromeric complex similar to that derived from HTC cell cytosol. GMEB-2 shares a unique KDWKR domain with proteins from diverse organisms, placing it in a novel family of transcription factors.","method":"PCR of degenerate oligonucleotides, 5'- and 3'-RACE cloning, in vitro transcription/translation, gel shift assays, antibody supershift","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro biochemical assays (gel shift, supershift, in vitro translation) directly demonstrating DNA binding and heteromeric complex formation, replicated across multiple methods in one rigorous study","pmids":["9651376"],"is_preprint":false},{"year":2000,"finding":"GMEB-1 and GMEB-2 each possess intrinsic transactivation activity in mammalian one-hybrid assays. Both proteins interact with glucocorticoid receptor (GR) in mammalian two-hybrid and pull-down assays. Both proteins also interact with CREB-binding protein (CBP) in two-hybrid assays. Neither protein has histone acetyltransferase (HAT) activity. Overexpression of either or both GMEBs causes a reversible right shift in the GR dose-response curve and decreased partial agonist activity of antisteroids, consistent with squelching of limiting cofactors.","method":"Mammalian one-hybrid assay, mammalian two-hybrid assay, GST pull-down assay, HAT activity assay, transient transfection with reporter gene","journal":"Molecular endocrinology (Baltimore, Md.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (two-hybrid, pull-down, transactivation assays, HAT assay) in one study establishing interactions and functional consequences","pmids":["10894151"],"is_preprint":false},{"year":2000,"finding":"GME activity requires an optimal position within 250 bp upstream of a tandem GRE driving a complex promoter. GMEB-1 and GMEB-2 mediate GME-dependent modulation of GR transcriptional properties via a pathway parallel to (not overlapping with) the GRE fold-induction pathway. Overexpression of CREB reduced GRE but not GME activity, and no effect of the GME was observed on GR binding to a single GRE.","method":"Transient transfection with reporter gene constructs varying GME position, phasing, and sequence; CREB overexpression; gel shift for GR binding","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic/reporter epistasis with multiple construct variations in a single lab, establishing pathway placement but no biochemical reconstitution","pmids":["10854715"],"is_preprint":false},{"year":2000,"finding":"Human GMEB-1 and rat GMEB-2 are encoded by distinct genes on chromosomes 1 and 20, respectively, but share highly conserved genomic structure including intron organization, indicating evolution from a single parent gene. Both genes are most highly expressed in fetal and developing tissues. Both possess promoter regions with high transcriptional activity in transiently transfected cells.","method":"Genomic sequencing, chromosomal mapping, Northern blot/tissue distribution analysis, promoter-reporter transfection","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct genomic characterization and promoter activity assays, single lab, multiple methods","pmids":["10734202"],"is_preprint":false},{"year":2003,"finding":"Crystal structure of the GMEB-1 SAND domain at 1.55 Å resolution was determined. The SAND domain is necessary and sufficient for binding to GME DNA. NMR and binding studies mapped the DNA recognition surface to an alpha-helical region exposing the conserved KDWK motif. Site-directed mutagenesis identified key residues for DNA binding. The GMEB1 SAND domain contains a zinc-binding motif not present in Sp100b SAND; zinc is not required for DNA binding but determines the C-terminal conformation of the domain. The GMEB2 SAND domain shares 80% sequence identity with GMEB1 SAND domain.","method":"X-ray crystallography (1.55 Å), NMR spectroscopy, binding assays, site-directed mutagenesis","journal":"Molecular endocrinology (Baltimore, Md.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with NMR, mutagenesis, and functional binding assays in a single rigorous study","pmids":["12702733"],"is_preprint":false},{"year":2004,"finding":"Structure/activity analysis of GMEB-2 showed that homo- and hetero-oligomerization, binding to GR, binding to CBP, DNA binding, and modulation of GR transcriptional properties (dose-response curve position and partial agonist activity) each require large regions of GMEB-2. Only intrinsic transactivation activity could be localized to a small region. Domain organization of GMEB-2 is extremely similar to GMEB-1, with quantitative differences in activity arising from amino acid sequence variation rather than global structural differences.","method":"Deletion mutagenesis of GMEB-2 constructs; mammalian two-hybrid assay; pull-down assay; transient transfection reporter assay","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic deletion mutagenesis with multiple functional readouts in a single lab study","pmids":["14705952"],"is_preprint":false},{"year":2007,"finding":"GMEB-2 can differentially modulate progesterone receptor (PR) versus glucocorticoid receptor (GR) induction parameters (EC50, partial agonist activity, Vmax) under otherwise identical conditions, demonstrating that GMEB-2's modulatory activity is not restricted to GR.","method":"Transient transfection reporter assays with PR and GR in parallel; comparison of dose-response curves","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional reporter assays for both receptor systems in one lab, single study","pmids":["18215457"],"is_preprint":false},{"year":2011,"finding":"siRNA knockdown of GMEB1 reversed the protective effect of IL-12 on dexamethasone-induced T cell apoptosis, placing GMEB1 (which interacts with GMEB2 as part of the GME binding complex) downstream of IL-12/PI3K/Akt signaling in T cell survival. IL-12 induced both GMEB1 and GMEB2 expression. This suggests GMEB proteins reduce transactivation of glucocorticoid receptor-mediated apoptotic gene induction.","method":"siRNA knockdown of GMEB1 in human T cells; flow cytometry for apoptosis; PI3K inhibitor treatment","journal":"Immunobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis via siRNA with defined apoptosis phenotype, single lab, single method for GMEB2 induction","pmids":["21840619"],"is_preprint":false},{"year":2022,"finding":"GMEB2 acts as a transcription factor that directly transactivates the ADRM1 promoter, increasing ADRM1 expression. The GMEB2/ADRM1 axis induces nuclear translocation of NF-κB, activating NF-κB signaling. GMEB2 knockdown inhibited colorectal cancer cell growth in vitro and in vivo. YTHDF1 (an m6A reader) recognizes and binds m6A sites on GMEB2 mRNA, enhancing its stability and thereby upregulating GMEB2 protein levels.","method":"GMEB2 knockdown (siRNA/shRNA), luciferase promoter assay for ADRM1, rescue experiments with ADRM1, NF-κB nuclear translocation assay, RIP (RNA immunoprecipitation) for YTHDF1-GMEB2 mRNA interaction, xenograft tumor model","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (promoter assay, knockdown rescue, RIP, in vivo xenograft) in a single lab study","pmids":["36551532"],"is_preprint":false}],"current_model":"GMEB2 is a nuclear DNA-binding protein that forms a heteromeric complex with GMEB1 via its SAND domain (which contains a conserved KDWK motif and a zinc-binding motif), binds the glucocorticoid modulatory element (GME) to modulate glucocorticoid and progesterone receptor transactivation by shifting the agonist dose-response curve and altering partial agonist activity, interacts directly with GR and CBP, possesses intrinsic transactivation activity localizable to a discrete protein region, transactivates the ADRM1 promoter to activate NF-κB signaling in cancer cells, and is itself post-transcriptionally regulated by the m6A reader YTHDF1, which stabilizes GMEB2 mRNA."},"narrative":{"mechanistic_narrative":"GMEB2 is a nuclear DNA-binding transcription factor that modulates steroid hormone receptor transactivation by acting at the glucocorticoid modulatory element (GME), a regulatory site functioning in a pathway parallel to and distinct from the canonical GRE fold-induction pathway [PMID:9651376, PMID:10854715]. GMEB2 binds GME DNA and forms a heteromeric complex with GMEB1, with DNA binding markedly enhanced upon co-assembly of the two proteins [PMID:9651376]; this DNA recognition is mediated by a SAND domain that is necessary and sufficient for GME binding and presents a conserved KDWK motif on an alpha-helical surface, with an associated zinc-binding motif shaping the domain's C-terminal conformation [PMID:12702733]. Functionally, GMEB2 possesses intrinsic transactivation activity and interacts directly with the glucocorticoid receptor (GR) and with the coactivator CBP, and its overexpression shifts the GR agonist dose-response curve rightward and decreases antisteroid partial agonist activity in a manner consistent with squelching of limiting cofactors [PMID:10894151]. This modulatory activity extends to the progesterone receptor, where GMEB2 differentially alters EC50, partial agonist activity, and Vmax, establishing it as a general modulator of steroid receptor pharmacology rather than a GR-specific factor [PMID:18215457]. Beyond hormone signaling, GMEB2 transactivates the ADRM1 promoter to drive NF-κB nuclear translocation and promote colorectal cancer cell growth, and its protein level is post-transcriptionally controlled by the m6A reader YTHDF1, which binds and stabilizes GMEB2 mRNA [PMID:36551532].","teleology":[{"year":1998,"claim":"Established GMEB2 as a sequence-specific DNA-binding protein and revealed that its GME binding is potentiated by heteromeric assembly with GMEB1, defining the molecular basis of the GME-binding complex.","evidence":"RACE cloning, in vitro transcription/translation, and gel shift/supershift assays demonstrating GME binding and GMEB1/GMEB2 heteromer formation","pmids":["9651376"],"confidence":"High","gaps":["DNA-binding domain not yet mapped at this stage","no functional consequence for transcription demonstrated yet","endogenous complex stoichiometry not resolved"]},{"year":2000,"claim":"Determined that GMEB2 modulates GR transactivation by interacting with GR and CBP and shifting the agonist dose-response curve, identifying cofactor squelching as the likely mechanism.","evidence":"Mammalian one- and two-hybrid assays, GST pull-down, HAT assays, and transient-transfection reporter assays","pmids":["10894151"],"confidence":"High","gaps":["GMEB2 has no intrinsic HAT activity, leaving the coactivator link indirect","identity of the squelched limiting cofactors not defined","interactions shown in heterologous assays, not at endogenous loci"]},{"year":2000,"claim":"Placed GME-mediated modulation in a regulatory pathway parallel to, and not overlapping with, the canonical GRE fold-induction pathway, clarifying where GMEB activity acts.","evidence":"Reporter constructs varying GME position/phasing/sequence, CREB overexpression, and gel shift for GR binding","pmids":["10854715"],"confidence":"Medium","gaps":["no biochemical reconstitution of the GME pathway","molecular mechanism distinguishing the two pathways not resolved","position-dependence basis unexplained"]},{"year":2000,"claim":"Showed GMEB1 and GMEB2 derive from a common ancestral gene with conserved genomic structure and are enriched in fetal/developing tissues, hinting at a developmental role.","evidence":"Genomic sequencing, chromosomal mapping, Northern tissue distribution, and promoter-reporter transfection","pmids":["10734202"],"confidence":"Medium","gaps":["developmental function not functionally tested","tissue expression descriptive only","regulation of GMEB2 transcription not characterized"]},{"year":2003,"claim":"Provided atomic-resolution definition of the SAND domain as the GME DNA-recognition module, with the KDWK motif on the binding surface and a zinc motif shaping domain conformation; GMEB2's SAND is 80% identical, extending the model to GMEB2.","evidence":"X-ray crystallography (1.55 Å) and NMR of GMEB1 SAND, binding assays, and site-directed mutagenesis","pmids":["12702733"],"confidence":"High","gaps":["GMEB2 SAND structure inferred from GMEB1, not directly solved","structural basis of heteromerization not addressed","DNA-bound complex structure not determined"]},{"year":2004,"claim":"Mapped GMEB2 functional architecture, showing that oligomerization, GR/CBP binding, DNA binding, and receptor modulation each require large protein regions while only transactivation localizes to a discrete region, and that GMEB2/GMEB1 differences are quantitative.","evidence":"Deletion mutagenesis with two-hybrid, pull-down, and reporter assays","pmids":["14705952"],"confidence":"Medium","gaps":["no high-resolution structure of full-length GMEB2","distributed functional regions preclude clean domain assignment","basis of quantitative GMEB1/GMEB2 functional differences not identified"]},{"year":2007,"claim":"Demonstrated GMEB2 modulates progesterone receptor as well as glucocorticoid receptor, broadening its role to general steroid-receptor pharmacology.","evidence":"Parallel PR and GR transient-transfection reporter dose-response assays","pmids":["18215457"],"confidence":"Medium","gaps":["tested only in reporter systems","endogenous PR target genes not examined","mechanism of differential receptor modulation unresolved"]},{"year":2011,"claim":"Connected GMEB proteins to IL-12/PI3K/Akt-driven T cell survival, indicating GMEB-mediated dampening of glucocorticoid receptor apoptotic gene induction.","evidence":"siRNA knockdown of GMEB1 in human T cells, apoptosis flow cytometry, and PI3K inhibition; IL-12 induction of GMEB1/GMEB2","pmids":["21840619"],"confidence":"Medium","gaps":["functional knockdown performed on GMEB1, not GMEB2 directly","GMEB2 measured only at the induction level","target apoptotic genes not identified"]},{"year":2022,"claim":"Revealed a GMEB2 oncogenic axis in which GMEB2 transactivates ADRM1 to activate NF-κB and drive colorectal cancer growth, and is itself stabilized post-transcriptionally by the m6A reader YTHDF1.","evidence":"GMEB2 knockdown, ADRM1 luciferase promoter assay, ADRM1 rescue, NF-κB translocation assay, YTHDF1 RIP, and xenograft model","pmids":["36551532"],"confidence":"Medium","gaps":["direct GMEB2 binding to the ADRM1 promoter (e.g., ChIP) not detailed","relationship between this NF-κB role and steroid-receptor modulation unclear","single-lab study in one cancer context"]},{"year":null,"claim":"How GMEB2 integrates its steroid-receptor modulatory function with its NF-κB-activating oncogenic role, and what determines its target-gene selectivity in each context, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["no unified model linking GME-based receptor modulation and ADRM1/NF-κB activation","genome-wide GMEB2 binding sites not defined","physiological roles in development and immunity not directly tested for GMEB2"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,4]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[1,8]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,6]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,8]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,8]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,8]}],"complexes":["GMEB1/GMEB2 GME-binding heteromeric complex"],"partners":["GMEB1","GR","CBP","YTHDF1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UKD1","full_name":"Glucocorticoid modulatory element-binding protein 2","aliases":["DNA-binding protein p79PIF","Parvovirus initiation factor p79","PIF p79"],"length_aa":530,"mass_kda":56.4,"function":"Trans-acting factor that binds to glucocorticoid modulatory elements (GME) present in the TAT (tyrosine aminotransferase) promoter and increases sensitivity to low concentrations of glucocorticoids. Also binds to the transferrin receptor promoter. Essential auxiliary factor for the replication of parvoviruses","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q9UKD1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GMEB2","classification":"Not Classified","n_dependent_lines":13,"n_total_lines":1208,"dependency_fraction":0.01076158940397351},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GMEB2","total_profiled":1310},"omim":[{"mim_id":"607451","title":"GLUCOCORTICOID MODULATORY ELEMENT-BINDING PROTEIN 2; GMEB2","url":"https://www.omim.org/entry/607451"},{"mim_id":"604409","title":"GLUCOCORTICOID MODULATORY ELEMENT-BINDING PROTEIN 1; GMEB1","url":"https://www.omim.org/entry/604409"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GMEB2"},"hgnc":{"alias_symbol":["P79PIF","KIAA1269","PIF79"],"prev_symbol":[]},"alphafold":{"accession":"Q9UKD1","domains":[{"cath_id":"3.10.390.10","chopping":"89-177","consensus_level":"medium","plddt":93.3774,"start":89,"end":177},{"cath_id":"1.20.5","chopping":"231-274","consensus_level":"high","plddt":88.9968,"start":231,"end":274}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UKD1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UKD1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UKD1-F1-predicted_aligned_error_v6.png","plddt_mean":59.97},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GMEB2","jax_strain_url":"https://www.jax.org/strain/search?query=GMEB2"},"sequence":{"accession":"Q9UKD1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UKD1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UKD1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UKD1"}},"corpus_meta":[{"pmid":"10894151","id":"PMC_10894151","title":"Properties of the glucocorticoid modulatory element binding proteins GMEB-1 and -2: potential new modifiers of glucocorticoid receptor transactivation and members of the family of KDWK proteins.","date":"2000","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/10894151","citation_count":44,"is_preprint":false},{"pmid":"12702733","id":"PMC_12702733","title":"Crystal structure and nuclear magnetic resonance analyses of the SAND domain from glucocorticoid modulatory element binding protein-1 reveals deoxyribonucleic acid and zinc binding regions.","date":"2003","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/12702733","citation_count":39,"is_preprint":false},{"pmid":"9651376","id":"PMC_9651376","title":"Cloning and characterization of a novel binding factor (GMEB-2) of the glucocorticoid modulatory element.","date":"1998","source":"The Journal of biological 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research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/31046799","citation_count":27,"is_preprint":false},{"pmid":"10854715","id":"PMC_10854715","title":"Ability of the glucocorticoid modulatory element to modify glucocorticoid receptor transactivation indicates parallel pathways for the expression of glucocorticoid modulatory element and glucocorticoid response element activities.","date":"2000","source":"Molecular and cellular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/10854715","citation_count":27,"is_preprint":false},{"pmid":"10386584","id":"PMC_10386584","title":"Cloning and characterization of hGMEB1, a novel glucocorticoid modulatory element binding protein.","date":"1999","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/10386584","citation_count":22,"is_preprint":false},{"pmid":"10734202","id":"PMC_10734202","title":"Genomic organization of human GMEB-1 and rat GMEB-2: structural conservation of two multifunctional 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GMEB-2 shares a unique KDWKR domain with proteins from diverse organisms, placing it in a novel family of transcription factors.\",\n      \"method\": \"PCR of degenerate oligonucleotides, 5'- and 3'-RACE cloning, in vitro transcription/translation, gel shift assays, antibody supershift\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro biochemical assays (gel shift, supershift, in vitro translation) directly demonstrating DNA binding and heteromeric complex formation, replicated across multiple methods in one rigorous study\",\n      \"pmids\": [\"9651376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"GMEB-1 and GMEB-2 each possess intrinsic transactivation activity in mammalian one-hybrid assays. Both proteins interact with glucocorticoid receptor (GR) in mammalian two-hybrid and pull-down assays. Both proteins also interact with CREB-binding protein (CBP) in two-hybrid assays. Neither protein has histone acetyltransferase (HAT) activity. Overexpression of either or both GMEBs causes a reversible right shift in the GR dose-response curve and decreased partial agonist activity of antisteroids, consistent with squelching of limiting cofactors.\",\n      \"method\": \"Mammalian one-hybrid assay, mammalian two-hybrid assay, GST pull-down assay, HAT activity assay, transient transfection with reporter gene\",\n      \"journal\": \"Molecular endocrinology (Baltimore, Md.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (two-hybrid, pull-down, transactivation assays, HAT assay) in one study establishing interactions and functional consequences\",\n      \"pmids\": [\"10894151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"GME activity requires an optimal position within 250 bp upstream of a tandem GRE driving a complex promoter. GMEB-1 and GMEB-2 mediate GME-dependent modulation of GR transcriptional properties via a pathway parallel to (not overlapping with) the GRE fold-induction pathway. Overexpression of CREB reduced GRE but not GME activity, and no effect of the GME was observed on GR binding to a single GRE.\",\n      \"method\": \"Transient transfection with reporter gene constructs varying GME position, phasing, and sequence; CREB overexpression; gel shift for GR binding\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic/reporter epistasis with multiple construct variations in a single lab, establishing pathway placement but no biochemical reconstitution\",\n      \"pmids\": [\"10854715\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Human GMEB-1 and rat GMEB-2 are encoded by distinct genes on chromosomes 1 and 20, respectively, but share highly conserved genomic structure including intron organization, indicating evolution from a single parent gene. Both genes are most highly expressed in fetal and developing tissues. Both possess promoter regions with high transcriptional activity in transiently transfected cells.\",\n      \"method\": \"Genomic sequencing, chromosomal mapping, Northern blot/tissue distribution analysis, promoter-reporter transfection\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct genomic characterization and promoter activity assays, single lab, multiple methods\",\n      \"pmids\": [\"10734202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Crystal structure of the GMEB-1 SAND domain at 1.55 Å resolution was determined. The SAND domain is necessary and sufficient for binding to GME DNA. NMR and binding studies mapped the DNA recognition surface to an alpha-helical region exposing the conserved KDWK motif. Site-directed mutagenesis identified key residues for DNA binding. The GMEB1 SAND domain contains a zinc-binding motif not present in Sp100b SAND; zinc is not required for DNA binding but determines the C-terminal conformation of the domain. The GMEB2 SAND domain shares 80% sequence identity with GMEB1 SAND domain.\",\n      \"method\": \"X-ray crystallography (1.55 Å), NMR spectroscopy, binding assays, site-directed mutagenesis\",\n      \"journal\": \"Molecular endocrinology (Baltimore, Md.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with NMR, mutagenesis, and functional binding assays in a single rigorous study\",\n      \"pmids\": [\"12702733\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Structure/activity analysis of GMEB-2 showed that homo- and hetero-oligomerization, binding to GR, binding to CBP, DNA binding, and modulation of GR transcriptional properties (dose-response curve position and partial agonist activity) each require large regions of GMEB-2. Only intrinsic transactivation activity could be localized to a small region. Domain organization of GMEB-2 is extremely similar to GMEB-1, with quantitative differences in activity arising from amino acid sequence variation rather than global structural differences.\",\n      \"method\": \"Deletion mutagenesis of GMEB-2 constructs; mammalian two-hybrid assay; pull-down assay; transient transfection reporter assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic deletion mutagenesis with multiple functional readouts in a single lab study\",\n      \"pmids\": [\"14705952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"GMEB-2 can differentially modulate progesterone receptor (PR) versus glucocorticoid receptor (GR) induction parameters (EC50, partial agonist activity, Vmax) under otherwise identical conditions, demonstrating that GMEB-2's modulatory activity is not restricted to GR.\",\n      \"method\": \"Transient transfection reporter assays with PR and GR in parallel; comparison of dose-response curves\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional reporter assays for both receptor systems in one lab, single study\",\n      \"pmids\": [\"18215457\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"siRNA knockdown of GMEB1 reversed the protective effect of IL-12 on dexamethasone-induced T cell apoptosis, placing GMEB1 (which interacts with GMEB2 as part of the GME binding complex) downstream of IL-12/PI3K/Akt signaling in T cell survival. IL-12 induced both GMEB1 and GMEB2 expression. This suggests GMEB proteins reduce transactivation of glucocorticoid receptor-mediated apoptotic gene induction.\",\n      \"method\": \"siRNA knockdown of GMEB1 in human T cells; flow cytometry for apoptosis; PI3K inhibitor treatment\",\n      \"journal\": \"Immunobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis via siRNA with defined apoptosis phenotype, single lab, single method for GMEB2 induction\",\n      \"pmids\": [\"21840619\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"GMEB2 acts as a transcription factor that directly transactivates the ADRM1 promoter, increasing ADRM1 expression. The GMEB2/ADRM1 axis induces nuclear translocation of NF-κB, activating NF-κB signaling. GMEB2 knockdown inhibited colorectal cancer cell growth in vitro and in vivo. YTHDF1 (an m6A reader) recognizes and binds m6A sites on GMEB2 mRNA, enhancing its stability and thereby upregulating GMEB2 protein levels.\",\n      \"method\": \"GMEB2 knockdown (siRNA/shRNA), luciferase promoter assay for ADRM1, rescue experiments with ADRM1, NF-κB nuclear translocation assay, RIP (RNA immunoprecipitation) for YTHDF1-GMEB2 mRNA interaction, xenograft tumor model\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (promoter assay, knockdown rescue, RIP, in vivo xenograft) in a single lab study\",\n      \"pmids\": [\"36551532\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GMEB2 is a nuclear DNA-binding protein that forms a heteromeric complex with GMEB1 via its SAND domain (which contains a conserved KDWK motif and a zinc-binding motif), binds the glucocorticoid modulatory element (GME) to modulate glucocorticoid and progesterone receptor transactivation by shifting the agonist dose-response curve and altering partial agonist activity, interacts directly with GR and CBP, possesses intrinsic transactivation activity localizable to a discrete protein region, transactivates the ADRM1 promoter to activate NF-κB signaling in cancer cells, and is itself post-transcriptionally regulated by the m6A reader YTHDF1, which stabilizes GMEB2 mRNA.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GMEB2 is a nuclear DNA-binding transcription factor that modulates steroid hormone receptor transactivation by acting at the glucocorticoid modulatory element (GME), a regulatory site functioning in a pathway parallel to and distinct from the canonical GRE fold-induction pathway [#0, #2]. GMEB2 binds GME DNA and forms a heteromeric complex with GMEB1, with DNA binding markedly enhanced upon co-assembly of the two proteins [#0]; this DNA recognition is mediated by a SAND domain that is necessary and sufficient for GME binding and presents a conserved KDWK motif on an alpha-helical surface, with an associated zinc-binding motif shaping the domain's C-terminal conformation [#4]. Functionally, GMEB2 possesses intrinsic transactivation activity and interacts directly with the glucocorticoid receptor (GR) and with the coactivator CBP, and its overexpression shifts the GR agonist dose-response curve rightward and decreases antisteroid partial agonist activity in a manner consistent with squelching of limiting cofactors [#1]. This modulatory activity extends to the progesterone receptor, where GMEB2 differentially alters EC50, partial agonist activity, and Vmax, establishing it as a general modulator of steroid receptor pharmacology rather than a GR-specific factor [#6]. Beyond hormone signaling, GMEB2 transactivates the ADRM1 promoter to drive NF-\\u03baB nuclear translocation and promote colorectal cancer cell growth, and its protein level is post-transcriptionally controlled by the m6A reader YTHDF1, which binds and stabilizes GMEB2 mRNA [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established GMEB2 as a sequence-specific DNA-binding protein and revealed that its GME binding is potentiated by heteromeric assembly with GMEB1, defining the molecular basis of the GME-binding complex.\",\n      \"evidence\": \"RACE cloning, in vitro transcription/translation, and gel shift/supershift assays demonstrating GME binding and GMEB1/GMEB2 heteromer formation\",\n      \"pmids\": [\"9651376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"DNA-binding domain not yet mapped at this stage\",\n        \"no functional consequence for transcription demonstrated yet\",\n        \"endogenous complex stoichiometry not resolved\"\n      ]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Determined that GMEB2 modulates GR transactivation by interacting with GR and CBP and shifting the agonist dose-response curve, identifying cofactor squelching as the likely mechanism.\",\n      \"evidence\": \"Mammalian one- and two-hybrid assays, GST pull-down, HAT assays, and transient-transfection reporter assays\",\n      \"pmids\": [\"10894151\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"GMEB2 has no intrinsic HAT activity, leaving the coactivator link indirect\",\n        \"identity of the squelched limiting cofactors not defined\",\n        \"interactions shown in heterologous assays, not at endogenous loci\"\n      ]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Placed GME-mediated modulation in a regulatory pathway parallel to, and not overlapping with, the canonical GRE fold-induction pathway, clarifying where GMEB activity acts.\",\n      \"evidence\": \"Reporter constructs varying GME position/phasing/sequence, CREB overexpression, and gel shift for GR binding\",\n      \"pmids\": [\"10854715\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"no biochemical reconstitution of the GME pathway\",\n        \"molecular mechanism distinguishing the two pathways not resolved\",\n        \"position-dependence basis unexplained\"\n      ]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Showed GMEB1 and GMEB2 derive from a common ancestral gene with conserved genomic structure and are enriched in fetal/developing tissues, hinting at a developmental role.\",\n      \"evidence\": \"Genomic sequencing, chromosomal mapping, Northern tissue distribution, and promoter-reporter transfection\",\n      \"pmids\": [\"10734202\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"developmental function not functionally tested\",\n        \"tissue expression descriptive only\",\n        \"regulation of GMEB2 transcription not characterized\"\n      ]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Provided atomic-resolution definition of the SAND domain as the GME DNA-recognition module, with the KDWK motif on the binding surface and a zinc motif shaping domain conformation; GMEB2's SAND is 80% identical, extending the model to GMEB2.\",\n      \"evidence\": \"X-ray crystallography (1.55 \\u00c5) and NMR of GMEB1 SAND, binding assays, and site-directed mutagenesis\",\n      \"pmids\": [\"12702733\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"GMEB2 SAND structure inferred from GMEB1, not directly solved\",\n        \"structural basis of heteromerization not addressed\",\n        \"DNA-bound complex structure not determined\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Mapped GMEB2 functional architecture, showing that oligomerization, GR/CBP binding, DNA binding, and receptor modulation each require large protein regions while only transactivation localizes to a discrete region, and that GMEB2/GMEB1 differences are quantitative.\",\n      \"evidence\": \"Deletion mutagenesis with two-hybrid, pull-down, and reporter assays\",\n      \"pmids\": [\"14705952\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"no high-resolution structure of full-length GMEB2\",\n        \"distributed functional regions preclude clean domain assignment\",\n        \"basis of quantitative GMEB1/GMEB2 functional differences not identified\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated GMEB2 modulates progesterone receptor as well as glucocorticoid receptor, broadening its role to general steroid-receptor pharmacology.\",\n      \"evidence\": \"Parallel PR and GR transient-transfection reporter dose-response assays\",\n      \"pmids\": [\"18215457\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"tested only in reporter systems\",\n        \"endogenous PR target genes not examined\",\n        \"mechanism of differential receptor modulation unresolved\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connected GMEB proteins to IL-12/PI3K/Akt-driven T cell survival, indicating GMEB-mediated dampening of glucocorticoid receptor apoptotic gene induction.\",\n      \"evidence\": \"siRNA knockdown of GMEB1 in human T cells, apoptosis flow cytometry, and PI3K inhibition; IL-12 induction of GMEB1/GMEB2\",\n      \"pmids\": [\"21840619\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"functional knockdown performed on GMEB1, not GMEB2 directly\",\n        \"GMEB2 measured only at the induction level\",\n        \"target apoptotic genes not identified\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed a GMEB2 oncogenic axis in which GMEB2 transactivates ADRM1 to activate NF-\\u03baB and drive colorectal cancer growth, and is itself stabilized post-transcriptionally by the m6A reader YTHDF1.\",\n      \"evidence\": \"GMEB2 knockdown, ADRM1 luciferase promoter assay, ADRM1 rescue, NF-\\u03baB translocation assay, YTHDF1 RIP, and xenograft model\",\n      \"pmids\": [\"36551532\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"direct GMEB2 binding to the ADRM1 promoter (e.g., ChIP) not detailed\",\n        \"relationship between this NF-\\u03baB role and steroid-receptor modulation unclear\",\n        \"single-lab study in one cancer context\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How GMEB2 integrates its steroid-receptor modulatory function with its NF-\\u03baB-activating oncogenic role, and what determines its target-gene selectivity in each context, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"no unified model linking GME-based receptor modulation and ADRM1/NF-\\u03baB activation\",\n        \"genome-wide GMEB2 binding sites not defined\",\n        \"physiological roles in development and immunity not directly tested for GMEB2\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"complexes\": [\n      \"GMEB1/GMEB2 GME-binding heteromeric complex\"\n    ],\n    \"partners\": [\n      \"GMEB1\",\n      \"GR\",\n      \"CBP\",\n      \"YTHDF1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}