{"gene":"MC2R","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2007,"finding":"Human MRAP isoforms (MRAPα and MRAPβ) are essential for ACTH binding to MC2R and for ACTH-induced cAMP production, but are not required for MC2R localization at the plasma membrane. MRAPβ confers higher cell-surface MC2R density and higher maximal cAMP responses compared to MRAPα. ACTH bound MC2R only in the presence of MRAP, demonstrated in isogenic HEK293 cells devoid of endogenous MCRs.","method":"Stable expression in HEK293/Flp-recombinase target site cells; cAMP assay; ACTH binding assay; immunofluorescence; epitope-tagged constructs (c-Myc, Flag, 6xHis)","journal":"Molecular endocrinology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal tagged constructs, multiple orthogonal assays (binding, cAMP, surface density, localization) in a clean isogenic system","pmids":["17456795"],"is_preprint":false},{"year":2011,"finding":"ACTH induces concentration-dependent, arrestin-, clathrin-, and dynamin-dependent internalization of the MC2R/MRAP1 complex, followed by colocalization with Rab4-, Rab5-, and Rab11-positive recycling endosomes; ~28% of internalized receptors recycle back to the plasma membrane and contribute to total cAMP accumulation. Specific intracellular Ser/Thr residues (T131, S140, T143, T147, T204, S208, S280) regulate plasma membrane targeting, function, and internalization of MC2R.","method":"HEK293/Flp-recombinase target site cells; pharmacological inhibitors (monensin, brefeldin A); site-directed mutagenesis of S/T residues; colocalization with Rab GTPase markers; cAMP assay","journal":"Molecular endocrinology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (pharmacological inhibition, mutagenesis, Rab colocalization, cAMP assay) in a single rigorous study","pmids":["21920850"],"is_preprint":false},{"year":2010,"finding":"The third and fourth transmembrane domains of MC2R are the main determinants of its intracellular retention in non-adrenal cells, while the N-terminal segment influences membrane transport efficiency. The fourth and fifth transmembrane domains are involved in ACTH-binding selectivity. These were identified using systematic chimeric MC2R/MC4R receptors.","method":"Chimeric receptor mutagenesis (15 constructs); confocal fluorescence microscopy with EGFP fusion; ACTH(1-24) binding assay; cAMP assay; quantitative cell-membrane localization analysis","journal":"Molecular and cellular endocrinology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic domain-swap mutagenesis with multiple orthogonal readouts (localization, binding, cAMP) in a single thorough study","pmids":["20206229"],"is_preprint":false},{"year":2014,"finding":"Both the ligand-recognition specificity determinant and the intracellular retention signal of MC2R are formed by a specific extracellular structure supported by correct transmembrane domain alignment. The aromatic-residue-rich segment of the second extracellular loop (EC2) is involved in effects mediated by the second ACTH pharmacophore (-K-K-R-R-). Replacement of 2–5 amino acid segments within TM domains with MC4R counterparts disrupted membrane trafficking or cAMP signaling.","method":"Directed mutagenesis (20 segment-replacement constructs); EGFP fusion; cAMP assay; membrane trafficking quantification","journal":"Journal of molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — systematic mutagenesis with functional readouts, single lab","pmids":["25074265"],"is_preprint":false},{"year":2004,"finding":"Two MC2R mutations (C21R and S247G) individually produce an inactive receptor lacking ligand binding and ACTH responsiveness, but their co-occurrence on the same allele leads to constitutively elevated basal cAMP accumulation (constitutive activation). Co-expression of the normal MC2R allele restores a normal ACTH dose-response despite the constitutive activity.","method":"Stable expression in Y6 cells; cAMP accumulation assay; ligand binding assay","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assays (cAMP, binding) in a validated cell system, single lab with two orthogonal readouts","pmids":["15062562"],"is_preprint":false},{"year":2010,"finding":"ACTH binding to MC2R activates p44/p42 MAPK and p38 MAPK phosphorylation via a cAMP/PKA-dependent pathway (blocked by H89, KI(6-22), Rp-cAMPS), but not via cAMP/Epac1/2 or arrestin-coupled internalization. Receptor recycling (sensitive to brefeldin A and monensin) also contributes to cAMP accumulation and MAPK phosphorylation.","method":"HEK293/Flp cells stably expressing MC2R + MRAPβ; pharmacological inhibitors; dominant-negative arrestin constructs; phospho-MAPK immunoblot; cAMP assay","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pharmacological tools and dominant-negative constructs in a defined cell system, single lab","pmids":["21195128"],"is_preprint":false},{"year":2003,"finding":"MC2R desensitization after agonist stimulation is protein kinase A (PKA)-dependent, whereas internalization is PKA-independent and requires a G protein-coupled receptor kinase (GRK). This was established using the Y1 and Y6 cell systems.","method":"Y1/Y6 cell expression system; kinase inhibitor studies; desensitization and internalization assays","journal":"Annals of the New York Academy of Sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — pharmacological dissection in defined cell systems, single study, abstract-level detail limits full tier assignment","pmids":["12851305"],"is_preprint":false},{"year":2010,"finding":"Loss of the MC2R C-terminus (K289fs and M290X mutations) impairs cell surface expression by blocking transport from the endoplasmic reticulum to the plasma membrane, abolishing ACTH responsiveness. Importantly, co-immunoprecipitation showed that these C-terminal mutants retain normal interaction with MRAP, indicating MRAP binding alone is insufficient for proper MC2R trafficking.","method":"OS3 cell-based reporter assay; cell surface expression assay; confocal localization; co-immunoprecipitation of mutant MC2R with MRAP; alanine substitution constructs","journal":"The Journal of clinical endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, confocal localization, and functional reporter assay in two cell systems, single lab","pmids":["20962024"],"is_preprint":false},{"year":2012,"finding":"The C-terminal domains of MRAP1 isoforms dictate their intracellular localization and differentially regulate ACTH-induced cAMP production: MRAPβ localizes predominantly at the plasma membrane and induces the highest cAMP accumulation, while MRAPα localizes near the nuclear envelope/intracellular endosomes and promotes MC2R targeting. MRAPβ and MRAPdCT exhibit dual membrane topology (N_cyto/C_exo and N_exo/C_cyto), while MRAPα adopts only N_cyto/C_exo topology at the plasma membrane. MRAP2 and MC2R mutually enhance MRAP1 isoform expression.","method":"Stable expression in HEK293/FRT and B16-G4F cells; confocal immunofluorescence; topology assays; cAMP accumulation assay","journal":"General and comparative endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — topology assays, localization imaging, and functional cAMP assay across two cell lines, single lab","pmids":["22366472"],"is_preprint":false},{"year":2000,"finding":"The human MC2R (ACTHR) promoter contains two SF-1 (steroidogenic factor 1) binding sites at -209 and -35 bp that are required for adrenal-specific basal expression; an AP-1 site at -764 to -503 is required for cAMP/forskolin-dependent transcriptional induction. Both AP-1 and SF-1 are required for the cAMP-dependent induction of MC2R. SF-1 is necessary but not sufficient alone to drive expression in non-adrenal cells.","method":"5' deletion reporter (luciferase) constructs in Y1, JEG3, and Cos-1 cells; EMSA; SF-1 overexpression; site-directed mutagenesis of binding elements","journal":"Endocrine journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA, reporter assay, and mutagenesis of cis-elements, multiple cell lines, single lab","pmids":["10811295"],"is_preprint":false},{"year":2004,"finding":"A peroxisome proliferator-response element (PPRE)-like sequence in the murine mc2-r promoter binds PPARγ and RXRα (confirmed in adipocyte nuclear extracts) and is required for adipocyte-specific transcriptional activation of mc2-r during 3T3-L1 differentiation. Mutation of the PPRE completely abrogated promoter activity in differentiated adipocytes. This reveals a novel, SF-1-independent mechanism for mc2-r transcription in adipocytes.","method":"5' deletion reporter analysis in undifferentiated and differentiated 3T3-L1 cells; EMSA with adipocyte nuclear extracts; PPARγ2/RXRα co-transfection; PPRE mutagenesis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA, reporter deletion analysis, mutagenesis, and co-transfection, multiple orthogonal methods, single lab","pmids":["15028712"],"is_preprint":false},{"year":2004,"finding":"An E-box element at -1020 bp in the human MC2R promoter mediates repression of MC2R expression in granulosa cells, involving interactions with factors including activator protein 4 (AP4). SF-1 is necessary but not sufficient for adrenal-specific MC2R expression, as it is expressed in granulosa cells but cannot drive MC2R expression there without the E-box-mediated repression being relieved.","method":"Luciferase reporter transfection in bovine adrenocortical and bovine granulosa cells; EMSA","journal":"Journal of molecular endocrinology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — EMSA and reporter assay, single lab, single study with limited mechanistic depth in abstract","pmids":["15171714"],"is_preprint":false},{"year":2010,"finding":"FOXL2 and NR5A1 (SF-1) synergistically activate Mc2r promoter transcription in mammalian adrenal systems. FOXL2 alone activates Mc2r promoter activity in a dose-dependent manner, and two distal NR5A1 response elements at -1410 and -975 bp are required for the synergistic effect.","method":"Mc2r promoter mapping; luciferase reporter co-transfection with FOXL2 and NR5A1 expression constructs in Y1 cells; deletion constructs","journal":"Biology of reproduction","confidence":"Low","confidence_rationale":"Tier 3 / Weak — reporter/co-transfection assay with deletion mapping, single lab, single method type","pmids":["20650879"],"is_preprint":false},{"year":2017,"finding":"JDP2 (Jun dimerization protein 2) acts as a transcriptional activator of the mouse Mc2r gene by binding cAMP response elements between -1320 and -720 bp (major binding site at -830 bp confirmed by ChIP). Phosphorylation of JDP2 is required for its Mc2r transcriptional activation, and SUMOylation of JDP2 modulates this activity.","method":"Luciferase reporter assay in Y1 cells; real-time ChIP; Mc2r promoter deletion mapping; phosphorylation-deficient and SUMO-deficient JDP2 mutants; Western blot","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP plus reporter plus mutagenesis, multiple orthogonal methods, single lab","pmids":["28146118"],"is_preprint":false},{"year":1995,"finding":"A homozygous Y254C mutation in the third extracellular loop of the ACTH receptor (MC2R) causes isolated glucocorticoid deficiency, likely by interfering with ligand binding. This establishes the third extracellular loop as important for ACTH binding.","method":"Direct sequencing of the intronless MC2R gene; mutation not found in 100 normal alleles; structural inference from receptor topology","journal":"The Journal of clinical endocrinology and metabolism","confidence":"Low","confidence_rationale":"Tier 3 / Weak — sequence-based inference of functional domain, no direct in vitro binding assay performed","pmids":["7608277"],"is_preprint":false},{"year":2017,"finding":"Alanine substitution studies on rainbow trout MC2R identified V159 in TM4, F171 in TM5, and F175 in TM5 as critical residues for receptor activation by ACTH. A triple alanine mutant (V159A/F171A/F175A) could not be activated by ACTH at concentrations up to 10⁻⁶ M, while cell surface trafficking was unimpaired, pointing to a specific role for TM4 and TM5 in ACTH binding/activation rather than trafficking.","method":"Single and triple alanine mutagenesis of rtMC2R; cAMP assay; Cell Surface ELISA for trafficking","journal":"General and comparative endocrinology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — systematic alanine mutagenesis with cAMP assay and surface ELISA to separate trafficking from activation, single lab","pmids":["28495271"],"is_preprint":false},{"year":2013,"finding":"In rat bone marrow stromal cells, ACTH promotes chondrogenic nodule formation and induces transient elevations in intracellular calcium via MC2R signaling. Neither α-MSH (MC5R agonist) nor γ2-MSH (MC3R agonist) replicated these effects, and the cells express MC2R and MRAP by immunoblot, implicating MC2R specifically. Dexamethasone upregulates MC2R and MRAP expression, amplifying ACTH responses.","method":"Bone marrow stromal cell culture; MC-R-specific peptide agonists; immunoblot of membrane fractions; calcium flux assay; chondrogenic nodule quantification","journal":"Cell and tissue research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — pharmacological specificity approach without direct MC2R KO or knockdown confirmation, single lab","pmids":["23358747"],"is_preprint":false},{"year":2022,"finding":"MC2R from the Senegal bichir (Polypterus senegalus, a basal bony fish) requires Mrap1 (but not Mrap2) for membrane trafficking and ACTH-stimulated activation, and is selective for ACTH over α-MSH, demonstrating that Mrap1 dependence and ACTH selectivity are ancestral features of all bony fish Mc2rs.","method":"Heterologous co-expression in CHO cells; luciferase cAMP reporter assay; stimulation with ACTH and α-MSH; multiple vertebrate Mrap1 constructs tested","journal":"General and comparative endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reconstituted functional assay in CHO cells with multiple Mrap1 orthologs, single lab","pmids":["35973587"],"is_preprint":false},{"year":2012,"finding":"In a patient with familial glucocorticoid deficiency lacking skin hyperpigmentation, co-existing homozygous MC2R T152K (trafficking-defective) and MC1R R160W mutations were identified. This experimentally demonstrates that ACTH-driven MC1R activation is the cause of skin hyperpigmentation in FGD, as loss of MC1R function abolishes hyperpigmentation even in the context of severely elevated ACTH.","method":"Whole-gene sequencing; in vitro characterization of MC2R T152K as trafficking defective; clinical phenotype correlation","journal":"The Journal of clinical endocrinology and metabolism","confidence":"Low","confidence_rationale":"Tier 3 / Weak — natural experiment with genetic evidence but limited direct in vitro functional assay detail in abstract for MC2R specifically","pmids":["22337906"],"is_preprint":false},{"year":2024,"finding":"CRN04894 (17h), a nonpeptide MC2R antagonist derived from MC4R ligand modification, potently and selectively blocks MC2R and suppresses ACTH-stimulated corticosterone secretion in a dose-dependent manner in rats following oral administration, confirming the pharmacological tractability of MC2R as a drug target.","method":"Structure-activity relationship medicinal chemistry; in vivo rat ACTH-stimulated corticosterone assay; oral dosing at ≥3 mg/kg","journal":"ACS medicinal chemistry letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo pharmacological validation with selective antagonist, single study","pmids":["38628803"],"is_preprint":false},{"year":2026,"finding":"CRISPR/Cas9-generated mc2r knockout zebrafish show impaired interrenal steroidogenesis and pronounced skin hyperpigmentation with increased numbers of melanophores and xanthophores (while preserving normal patterning), with transcriptomic upregulation of genes involved in melanosome formation, melanin synthesis, lipid metabolism, and carotenoid accumulation. This establishes a direct role for MC2R in steroidogenesis and in restraining pigment cell development.","method":"CRISPR/Cas9 mc2r knockout in zebrafish; histological quantification of pigment cells; transcriptomic analysis","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined cellular and transcriptomic phenotypes, single study","pmids":["41639367"],"is_preprint":false},{"year":2022,"finding":"In vitro study in HEK293 cells transfected with wild-type and MC2R mutant (p.Leu109Gln) plasmids showed defects in MC2R protein expression and cAMP generation upon ACTH stimulation, functionally confirming pathogenicity of this novel missense mutation.","method":"HEK293 cell transfection; cAMP assay; Western blot protein expression","journal":"Journal of the Endocrine Society","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single in vitro assay in a heterologous system, single lab, single variant","pmids":["35506146"],"is_preprint":false}],"current_model":"MC2R (ACTHR) is a G protein-coupled receptor that selectively binds ACTH and signals via cAMP/PKA to drive adrenocortical steroidogenesis and pigment cell regulation; it requires the accessory protein MRAP1 for ACTH binding and functional cAMP signaling (though not for plasma membrane localization per se), undergoes PKA-dependent desensitization and GRK-dependent, arrestin/clathrin/dynamin-mediated internalization followed by Rab-mediated recycling, with ACTH-binding specificity mapped to TM4/TM5 and the second extracellular loop, intracellular retention signals in TM3/TM4, and transcriptional regulation driven cooperatively by SF-1, AP-1, PPARγ/RXRα (in adipocytes), FOXL2/NR5A1, and JDP2."},"narrative":{"mechanistic_narrative":"MC2R (the ACTH receptor) is a G protein-coupled receptor that drives adrenocortical steroidogenesis and restrains pigment cell development, as established by mc2r knockout in zebrafish, which impairs interrenal steroidogenesis and produces skin hyperpigmentation with expanded melanophore and xanthophore populations [PMID:41639367]. Productive ACTH binding and cAMP signaling require the accessory protein MRAP, without which ACTH does not bind MC2R, even though MRAP is dispensable for plasma membrane localization per se; MRAPβ confers higher cell-surface receptor density and maximal cAMP output than MRAPα, and the MRAP isoforms' C-termini dictate their topology and subcellular localization to tune receptor targeting and signaling [PMID:17456795, PMID:22366472]. This MRAP1 dependence together with ACTH selectivity over α-MSH is an ancestral feature conserved across bony fish [PMID:35973587]. ACTH binding specificity and activation are governed by the fourth and fifth transmembrane domains and by an aromatic-residue-rich segment of the second extracellular loop, while intracellular retention signals reside in TM3/TM4 and the N-terminus modulates trafficking efficiency [PMID:20206229, PMID:25074265, PMID:28495271]. Downstream, ACTH/MC2R signals through cAMP/PKA to activate p44/p42 and p38 MAPK [PMID:21195128], drives PKA-dependent desensitization and GRK-dependent, arrestin/clathrin/dynamin-mediated internalization, followed by Rab4/5/11-dependent recycling that itself contributes to total cAMP accumulation [PMID:21920850, PMID:12851305]. Transcription of MC2R is controlled in a tissue-specific manner: SF-1 (NR5A1) cooperating with an AP-1 element drives adrenal-specific and cAMP-inducible expression [PMID:10811295], FOXL2 synergizes with NR5A1 [PMID:20650879], JDP2 acts as a cAMP-response-element-binding activator [PMID:28146118], and a PPARγ/RXRα-bound PPRE mediates SF-1-independent expression in adipocytes [PMID:15028712]. Loss-of-function MC2R mutations cause familial/isolated glucocorticoid deficiency, with separate variants disrupting ligand binding, cell-surface trafficking, or protein expression [PMID:20962024, PMID:7608277, PMID:35506146].","teleology":[{"year":1995,"claim":"Before any in vitro structure-function work, a patient mutation implicated specific receptor regions in ACTH binding and linked MC2R loss to disease.","evidence":"Direct sequencing of the intronless MC2R gene identifying a homozygous Y254C in the third extracellular loop in isolated glucocorticoid deficiency","pmids":["7608277"],"confidence":"Low","gaps":["No direct in vitro binding assay performed","Functional consequence inferred from topology, not measured"]},{"year":2000,"claim":"Established how MC2R achieves adrenal-specific and cAMP-inducible expression, defining the core transcriptional logic of the receptor.","evidence":"5' deletion luciferase reporters, EMSA, and SF-1 overexpression/mutagenesis in Y1, JEG3, and Cos-1 cells","pmids":["10811295"],"confidence":"Medium","gaps":["SF-1 alone insufficient in non-adrenal cells; additional co-factors needed","Promoter context studied in cell lines, not endogenous chromatin"]},{"year":2003,"claim":"Separated the kinases controlling MC2R desensitization versus internalization, distinguishing two regulatory arms of signaling termination.","evidence":"Y1/Y6 cell expression with kinase inhibitor studies and desensitization/internalization assays","pmids":["12851305"],"confidence":"Medium","gaps":["Which specific GRK acts on MC2R not identified","Abstract-level mechanistic detail only"]},{"year":2004,"claim":"Identified a tissue-specific, SF-1-independent route to MC2R transcription, explaining adipocyte expression.","evidence":"5' deletion reporters in differentiating 3T3-L1 cells, EMSA with adipocyte nuclear extracts, PPARγ2/RXRα co-transfection and PPRE mutagenesis","pmids":["15028712"],"confidence":"Medium","gaps":["Studied in murine adipocyte model only","Physiological role of adipocyte MC2R not established"]},{"year":2004,"claim":"Showed that combinations of individually inactivating mutations can yield constitutive MC2R activity, revealing allele-level interaction effects.","evidence":"Stable expression of C21R/S247G single and double mutants in Y6 cells with cAMP accumulation and ligand binding assays","pmids":["15062562"],"confidence":"Medium","gaps":["Structural basis of constitutive activation not resolved","Clinical correlate of compound allele not established"]},{"year":2004,"claim":"Defined repressive cis-regulation that prevents MC2R expression where SF-1 is present but the receptor should be silent.","evidence":"Luciferase reporters and EMSA in bovine adrenocortical versus granulosa cells","pmids":["15171714"],"confidence":"Low","gaps":["Single method type with limited mechanistic depth","AP4 involvement not definitively established"]},{"year":2007,"claim":"Resolved the long-standing problem of MC2R functional reconstitution by showing MRAP is required for ACTH binding and signaling but not surface localization.","evidence":"Stable MC2R + MRAPα/β expression in isogenic HEK293/FRT cells lacking endogenous MCRs, with binding, cAMP, surface density, and localization readouts","pmids":["17456795"],"confidence":"High","gaps":["Molecular mechanism by which MRAP enables binding not resolved","Stoichiometry of MC2R/MRAP complex not defined here"]},{"year":2010,"claim":"Mapped the MC2R domains responsible for intracellular retention versus ACTH-binding selectivity, separating trafficking from ligand recognition.","evidence":"Systematic MC2R/MC4R chimeric constructs with confocal localization, ACTH(1-24) binding, and cAMP assays","pmids":["20206229"],"confidence":"High","gaps":["Residue-level binding contacts not defined","No structural model of the binding pocket"]},{"year":2010,"claim":"Defined the downstream effector cascade, showing MC2R activates MAPK strictly through cAMP/PKA and not via Epac or arrestin.","evidence":"HEK293/FRT cells expressing MC2R + MRAPβ with pharmacological inhibitors, dominant-negative arrestin, and phospho-MAPK immunoblot","pmids":["21195128"],"confidence":"Medium","gaps":["Downstream physiological output of MAPK activation not addressed","Single cell system"]},{"year":2010,"claim":"Showed that MRAP binding is insufficient for MC2R trafficking, identifying the C-terminus as an independent trafficking determinant in disease.","evidence":"OS3/cell surface expression assays, confocal localization, and co-IP of C-terminal mutants (K289fs, M290X) with MRAP","pmids":["20962024"],"confidence":"Medium","gaps":["C-terminal trafficking motif not precisely defined","Single lab"]},{"year":2010,"claim":"Added FOXL2 to the transcriptional network controlling MC2R, demonstrating synergy with NR5A1.","evidence":"Mc2r promoter mapping and luciferase co-transfection with FOXL2 and NR5A1 in Y1 cells","pmids":["20650879"],"confidence":"Low","gaps":["Single assay type (reporter/co-transfection)","Endogenous FOXL2 occupancy not shown"]},{"year":2011,"claim":"Characterized the full internalization/recycling itinerary of activated MC2R and showed recycling sustains cAMP output.","evidence":"HEK293/FRT cells with monensin/brefeldin A inhibitors, S/T residue mutagenesis, Rab GTPase colocalization, and cAMP assays","pmids":["21920850"],"confidence":"High","gaps":["Adaptor proteins linking MC2R to clathrin not identified","Studied in heterologous cells, not adrenal cells"]},{"year":2012,"claim":"Defined how MRAP1 isoform C-termini and membrane topology differentially tune MC2R localization and cAMP output.","evidence":"Stable expression in HEK293/FRT and B16-G4F cells with confocal imaging, topology assays, and cAMP accumulation","pmids":["22366472"],"confidence":"Medium","gaps":["Functional significance of dual topology in vivo unclear","MRAP2 role only partially addressed"]},{"year":2012,"claim":"Used a natural human double-mutant to prove that ACTH-driven MC1R activation, not MC2R itself, causes the skin hyperpigmentation seen in glucocorticoid deficiency.","evidence":"Whole-gene sequencing plus in vitro characterization of MC2R T152K as trafficking-defective with clinical phenotype correlation","pmids":["22337906"],"confidence":"Low","gaps":["Limited in vitro functional detail for MC2R variant","Single family"]},{"year":2014,"claim":"Refined the structural basis of ACTH recognition, implicating the EC2 aromatic segment in engaging the second ACTH pharmacophore.","evidence":"Twenty segment-replacement (MC2R/MC4R) constructs with EGFP localization and cAMP assays","pmids":["25074265"],"confidence":"Medium","gaps":["No direct binding measurements, only functional readout","Single lab"]},{"year":2017,"claim":"Pinpointed individual TM4/TM5 residues required for ACTH activation while leaving trafficking intact, separating activation from surface delivery.","evidence":"Single and triple alanine mutagenesis of rainbow trout MC2R with cAMP assay and cell surface ELISA","pmids":["28495271"],"confidence":"Medium","gaps":["Demonstrated in fish ortholog; human residue conservation not directly tested","No structural confirmation of contacts"]},{"year":2017,"claim":"Added JDP2 as a CRE-binding transcriptional activator of Mc2r and showed its activity depends on phosphorylation and SUMOylation.","evidence":"Luciferase reporters, real-time ChIP, promoter deletion mapping, and phospho-/SUMO-deficient JDP2 mutants in Y1 cells","pmids":["28146118"],"confidence":"Medium","gaps":["Upstream signals controlling JDP2 modification in adrenal cells unclear","Mouse promoter context"]},{"year":2022,"claim":"Established the evolutionary depth of MC2R's MRAP1 dependence and ACTH selectivity in a basal bony fish.","evidence":"Heterologous co-expression of Polypterus MC2R with multiple Mrap1 orthologs in CHO cells and luciferase cAMP reporter with ACTH and α-MSH","pmids":["35973587"],"confidence":"Medium","gaps":["Does not address human-specific regulation","Single lab"]},{"year":2022,"claim":"Functionally confirmed pathogenicity of a novel disease missense variant through expression and signaling defects.","evidence":"HEK293 transfection of wild-type and p.Leu109Gln MC2R with cAMP assay and Western blot","pmids":["35506146"],"confidence":"Low","gaps":["Single in vitro assay in heterologous system","Mechanism of defect (folding vs trafficking) not dissected"]},{"year":2024,"claim":"Validated MC2R as a druggable target by demonstrating an orally active selective antagonist suppresses ACTH-driven steroid output in vivo.","evidence":"SAR medicinal chemistry yielding CRN04894 with in vivo rat ACTH-stimulated corticosterone assay after oral dosing","pmids":["38628803"],"confidence":"Medium","gaps":["Binding mode on MC2R not structurally defined","Efficacy in disease models not shown"]},{"year":2026,"claim":"Provided in vivo genetic proof that MC2R is required for steroidogenesis and restrains pigment cell development.","evidence":"CRISPR/Cas9 mc2r knockout zebrafish with histological pigment cell quantification and transcriptomic analysis","pmids":["41639367"],"confidence":"Medium","gaps":["Pigment phenotype mechanism (cell-autonomous vs systemic ACTH/MC1R) not dissected in this system","Mammalian relevance of pigment role not established"]},{"year":null,"claim":"A high-resolution structure of the MC2R/MRAP/ACTH complex defining how MRAP enables ligand binding and how TM4/TM5 and EC2 contact ACTH remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No experimental structure of the activated complex","Molecular mechanism of MRAP-dependent binding not defined","Stoichiometry of MC2R:MRAP not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,1,5]},{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[0,2,15]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,8,2]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[1,8]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[7]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,5,1]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[9,10,13]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[20]}],"complexes":["MC2R/MRAP1 receptor complex"],"partners":["MRAP","MRAP2","SF-1/NR5A1","FOXL2","JDP2","PPARG","RXRA"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q01718","full_name":"Adrenocorticotropic hormone receptor","aliases":["Adrenocorticotropin receptor","Melanocortin receptor 2","MC2-R"],"length_aa":297,"mass_kda":33.9,"function":"G protein-coupled receptor for corticotropin/ACTH, primarily expressed in adrenal cortex where it plays a key role in the regulation of adrenocortical function (PubMed:1325670, PubMed:17596328, PubMed:36588120). Upon activation, couples to G(s) protein, stimulating adenylate cyclase and activating the cAMP-dependent signaling pathway, the MAPK cascade as well as the PKA pathway, leading to steroidogenic factor 1/NR5A1-mediated transcriptional activation (PubMed:1325670). Activation by ACTH facilitates the release of adrenal glucocorticoids, including cortisol and corticosterone (PubMed:12213892, PubMed:8636348). In addition, MC2R is required for fetal and neonatal adrenal gland development (By similarity)","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q01718/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MC2R","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MC2R","total_profiled":1310},"omim":[{"mim_id":"615549","title":"ARMADILLO REPEAT-CONTAINING PROTEIN 5; ARMC5","url":"https://www.omim.org/entry/615549"},{"mim_id":"615410","title":"MELANOCORTIN 2 RECEPTOR ACCESSORY PROTEIN 2; MRAP2","url":"https://www.omim.org/entry/615410"},{"mim_id":"614736","title":"GLUCOCORTICOID DEFICIENCY 4 WITH OR WITHOUT MINERALOCORTICOID DEFICIENCY; GCCD4","url":"https://www.omim.org/entry/614736"},{"mim_id":"609197","title":"GLUCOCORTICOID DEFICIENCY 3; GCCD3","url":"https://www.omim.org/entry/609197"},{"mim_id":"609196","title":"MELANOCORTIN 2 RECEPTOR ACCESSORY PROTEIN; MRAP","url":"https://www.omim.org/entry/609196"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"adrenal gland","ntpm":50.6}],"url":"https://www.proteinatlas.org/search/MC2R"},"hgnc":{"alias_symbol":["ACTHR"],"prev_symbol":[]},"alphafold":{"accession":"Q01718","domains":[{"cath_id":"1.20.1070.10","chopping":"1-15_26-282","consensus_level":"medium","plddt":85.6953,"start":1,"end":282}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q01718","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q01718-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q01718-F1-predicted_aligned_error_v6.png","plddt_mean":85.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MC2R","jax_strain_url":"https://www.jax.org/strain/search?query=MC2R"},"sequence":{"accession":"Q01718","fasta_url":"https://rest.uniprot.org/uniprotkb/Q01718.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q01718/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q01718"}},"corpus_meta":[{"pmid":"17456795","id":"PMC_17456795","title":"Differential regulation of the human adrenocorticotropin receptor [melanocortin-2 receptor (MC2R)] by human MC2R accessory protein isoforms alpha and beta in isogenic human embryonic kidney 293 cells.","date":"2007","source":"Molecular endocrinology (Baltimore, Md.)","url":"https://pubmed.ncbi.nlm.nih.gov/17456795","citation_count":85,"is_preprint":false},{"pmid":"28220105","id":"PMC_28220105","title":"ACTH Receptor (MC2R) Specificity: What Do We Know About Underlying Molecular Mechanisms?","date":"2017","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/28220105","citation_count":61,"is_preprint":false},{"pmid":"17223989","id":"PMC_17223989","title":"Severe loss-of-function mutations in the adrenocorticotropin receptor (ACTHR, MC2R) can be found in patients diagnosed with salt-losing adrenal hypoplasia.","date":"2007","source":"Clinical endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/17223989","citation_count":61,"is_preprint":false},{"pmid":"7608277","id":"PMC_7608277","title":"A novel mutation of the adrenocorticotropin receptor (ACTH-R) gene in a family with the syndrome of isolated glucocorticoid deficiency, but no ACTH-R abnormalities in two families with the triple A syndrome.","date":"1995","source":"The Journal of clinical endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/7608277","citation_count":60,"is_preprint":false},{"pmid":"15062562","id":"PMC_15062562","title":"Constitutive activation of the human ACTH receptor resulting from a synergistic interaction between two naturally occurring missense mutations in the MC2R gene.","date":"2004","source":"Molecular and cellular endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/15062562","citation_count":43,"is_preprint":false},{"pmid":"23724142","id":"PMC_23724142","title":"Molecular characterization and functional regulation of melanocortin 2 receptor (MC2R) in the sea bass. 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melanocortin-2-receptor (mc2r) lead to skin hyperpigmentation in teleost fish.","date":"2026","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/41639367","citation_count":0,"is_preprint":false},{"pmid":"40729435","id":"PMC_40729435","title":"Uniparental disomy leads to a novel cause of MC2R-related familial glucocorticoid deficiency type 1.","date":"2025","source":"European journal of endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/40729435","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.13.682090","title":"PERINATAL ORGANOPHOSPHATE FLAME RETARDANT EXPOSURE ALTERS ADULT STRESS AXIS AND AVOIDANCE BEHAVIOR IN MICE","date":"2025-10-14","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.13.682090","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":37813,"output_tokens":5873,"usd":0.100767,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14449,"output_tokens":5615,"usd":0.10631,"stage2_stop_reason":"end_turn"},"total_usd":0.207077,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"Human MRAP isoforms (MRAPα and MRAPβ) are essential for ACTH binding to MC2R and for ACTH-induced cAMP production, but are not required for MC2R localization at the plasma membrane. MRAPβ confers higher cell-surface MC2R density and higher maximal cAMP responses compared to MRAPα. ACTH bound MC2R only in the presence of MRAP, demonstrated in isogenic HEK293 cells devoid of endogenous MCRs.\",\n      \"method\": \"Stable expression in HEK293/Flp-recombinase target site cells; cAMP assay; ACTH binding assay; immunofluorescence; epitope-tagged constructs (c-Myc, Flag, 6xHis)\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal tagged constructs, multiple orthogonal assays (binding, cAMP, surface density, localization) in a clean isogenic system\",\n      \"pmids\": [\"17456795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ACTH induces concentration-dependent, arrestin-, clathrin-, and dynamin-dependent internalization of the MC2R/MRAP1 complex, followed by colocalization with Rab4-, Rab5-, and Rab11-positive recycling endosomes; ~28% of internalized receptors recycle back to the plasma membrane and contribute to total cAMP accumulation. Specific intracellular Ser/Thr residues (T131, S140, T143, T147, T204, S208, S280) regulate plasma membrane targeting, function, and internalization of MC2R.\",\n      \"method\": \"HEK293/Flp-recombinase target site cells; pharmacological inhibitors (monensin, brefeldin A); site-directed mutagenesis of S/T residues; colocalization with Rab GTPase markers; cAMP assay\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (pharmacological inhibition, mutagenesis, Rab colocalization, cAMP assay) in a single rigorous study\",\n      \"pmids\": [\"21920850\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The third and fourth transmembrane domains of MC2R are the main determinants of its intracellular retention in non-adrenal cells, while the N-terminal segment influences membrane transport efficiency. The fourth and fifth transmembrane domains are involved in ACTH-binding selectivity. These were identified using systematic chimeric MC2R/MC4R receptors.\",\n      \"method\": \"Chimeric receptor mutagenesis (15 constructs); confocal fluorescence microscopy with EGFP fusion; ACTH(1-24) binding assay; cAMP assay; quantitative cell-membrane localization analysis\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic domain-swap mutagenesis with multiple orthogonal readouts (localization, binding, cAMP) in a single thorough study\",\n      \"pmids\": [\"20206229\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Both the ligand-recognition specificity determinant and the intracellular retention signal of MC2R are formed by a specific extracellular structure supported by correct transmembrane domain alignment. The aromatic-residue-rich segment of the second extracellular loop (EC2) is involved in effects mediated by the second ACTH pharmacophore (-K-K-R-R-). Replacement of 2–5 amino acid segments within TM domains with MC4R counterparts disrupted membrane trafficking or cAMP signaling.\",\n      \"method\": \"Directed mutagenesis (20 segment-replacement constructs); EGFP fusion; cAMP assay; membrane trafficking quantification\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic mutagenesis with functional readouts, single lab\",\n      \"pmids\": [\"25074265\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Two MC2R mutations (C21R and S247G) individually produce an inactive receptor lacking ligand binding and ACTH responsiveness, but their co-occurrence on the same allele leads to constitutively elevated basal cAMP accumulation (constitutive activation). Co-expression of the normal MC2R allele restores a normal ACTH dose-response despite the constitutive activity.\",\n      \"method\": \"Stable expression in Y6 cells; cAMP accumulation assay; ligand binding assay\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assays (cAMP, binding) in a validated cell system, single lab with two orthogonal readouts\",\n      \"pmids\": [\"15062562\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ACTH binding to MC2R activates p44/p42 MAPK and p38 MAPK phosphorylation via a cAMP/PKA-dependent pathway (blocked by H89, KI(6-22), Rp-cAMPS), but not via cAMP/Epac1/2 or arrestin-coupled internalization. Receptor recycling (sensitive to brefeldin A and monensin) also contributes to cAMP accumulation and MAPK phosphorylation.\",\n      \"method\": \"HEK293/Flp cells stably expressing MC2R + MRAPβ; pharmacological inhibitors; dominant-negative arrestin constructs; phospho-MAPK immunoblot; cAMP assay\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pharmacological tools and dominant-negative constructs in a defined cell system, single lab\",\n      \"pmids\": [\"21195128\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MC2R desensitization after agonist stimulation is protein kinase A (PKA)-dependent, whereas internalization is PKA-independent and requires a G protein-coupled receptor kinase (GRK). This was established using the Y1 and Y6 cell systems.\",\n      \"method\": \"Y1/Y6 cell expression system; kinase inhibitor studies; desensitization and internalization assays\",\n      \"journal\": \"Annals of the New York Academy of Sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — pharmacological dissection in defined cell systems, single study, abstract-level detail limits full tier assignment\",\n      \"pmids\": [\"12851305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Loss of the MC2R C-terminus (K289fs and M290X mutations) impairs cell surface expression by blocking transport from the endoplasmic reticulum to the plasma membrane, abolishing ACTH responsiveness. Importantly, co-immunoprecipitation showed that these C-terminal mutants retain normal interaction with MRAP, indicating MRAP binding alone is insufficient for proper MC2R trafficking.\",\n      \"method\": \"OS3 cell-based reporter assay; cell surface expression assay; confocal localization; co-immunoprecipitation of mutant MC2R with MRAP; alanine substitution constructs\",\n      \"journal\": \"The Journal of clinical endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, confocal localization, and functional reporter assay in two cell systems, single lab\",\n      \"pmids\": [\"20962024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The C-terminal domains of MRAP1 isoforms dictate their intracellular localization and differentially regulate ACTH-induced cAMP production: MRAPβ localizes predominantly at the plasma membrane and induces the highest cAMP accumulation, while MRAPα localizes near the nuclear envelope/intracellular endosomes and promotes MC2R targeting. MRAPβ and MRAPdCT exhibit dual membrane topology (N_cyto/C_exo and N_exo/C_cyto), while MRAPα adopts only N_cyto/C_exo topology at the plasma membrane. MRAP2 and MC2R mutually enhance MRAP1 isoform expression.\",\n      \"method\": \"Stable expression in HEK293/FRT and B16-G4F cells; confocal immunofluorescence; topology assays; cAMP accumulation assay\",\n      \"journal\": \"General and comparative endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — topology assays, localization imaging, and functional cAMP assay across two cell lines, single lab\",\n      \"pmids\": [\"22366472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The human MC2R (ACTHR) promoter contains two SF-1 (steroidogenic factor 1) binding sites at -209 and -35 bp that are required for adrenal-specific basal expression; an AP-1 site at -764 to -503 is required for cAMP/forskolin-dependent transcriptional induction. Both AP-1 and SF-1 are required for the cAMP-dependent induction of MC2R. SF-1 is necessary but not sufficient alone to drive expression in non-adrenal cells.\",\n      \"method\": \"5' deletion reporter (luciferase) constructs in Y1, JEG3, and Cos-1 cells; EMSA; SF-1 overexpression; site-directed mutagenesis of binding elements\",\n      \"journal\": \"Endocrine journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA, reporter assay, and mutagenesis of cis-elements, multiple cell lines, single lab\",\n      \"pmids\": [\"10811295\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"A peroxisome proliferator-response element (PPRE)-like sequence in the murine mc2-r promoter binds PPARγ and RXRα (confirmed in adipocyte nuclear extracts) and is required for adipocyte-specific transcriptional activation of mc2-r during 3T3-L1 differentiation. Mutation of the PPRE completely abrogated promoter activity in differentiated adipocytes. This reveals a novel, SF-1-independent mechanism for mc2-r transcription in adipocytes.\",\n      \"method\": \"5' deletion reporter analysis in undifferentiated and differentiated 3T3-L1 cells; EMSA with adipocyte nuclear extracts; PPARγ2/RXRα co-transfection; PPRE mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA, reporter deletion analysis, mutagenesis, and co-transfection, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"15028712\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"An E-box element at -1020 bp in the human MC2R promoter mediates repression of MC2R expression in granulosa cells, involving interactions with factors including activator protein 4 (AP4). SF-1 is necessary but not sufficient for adrenal-specific MC2R expression, as it is expressed in granulosa cells but cannot drive MC2R expression there without the E-box-mediated repression being relieved.\",\n      \"method\": \"Luciferase reporter transfection in bovine adrenocortical and bovine granulosa cells; EMSA\",\n      \"journal\": \"Journal of molecular endocrinology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — EMSA and reporter assay, single lab, single study with limited mechanistic depth in abstract\",\n      \"pmids\": [\"15171714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"FOXL2 and NR5A1 (SF-1) synergistically activate Mc2r promoter transcription in mammalian adrenal systems. FOXL2 alone activates Mc2r promoter activity in a dose-dependent manner, and two distal NR5A1 response elements at -1410 and -975 bp are required for the synergistic effect.\",\n      \"method\": \"Mc2r promoter mapping; luciferase reporter co-transfection with FOXL2 and NR5A1 expression constructs in Y1 cells; deletion constructs\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — reporter/co-transfection assay with deletion mapping, single lab, single method type\",\n      \"pmids\": [\"20650879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"JDP2 (Jun dimerization protein 2) acts as a transcriptional activator of the mouse Mc2r gene by binding cAMP response elements between -1320 and -720 bp (major binding site at -830 bp confirmed by ChIP). Phosphorylation of JDP2 is required for its Mc2r transcriptional activation, and SUMOylation of JDP2 modulates this activity.\",\n      \"method\": \"Luciferase reporter assay in Y1 cells; real-time ChIP; Mc2r promoter deletion mapping; phosphorylation-deficient and SUMO-deficient JDP2 mutants; Western blot\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP plus reporter plus mutagenesis, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"28146118\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"A homozygous Y254C mutation in the third extracellular loop of the ACTH receptor (MC2R) causes isolated glucocorticoid deficiency, likely by interfering with ligand binding. This establishes the third extracellular loop as important for ACTH binding.\",\n      \"method\": \"Direct sequencing of the intronless MC2R gene; mutation not found in 100 normal alleles; structural inference from receptor topology\",\n      \"journal\": \"The Journal of clinical endocrinology and metabolism\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — sequence-based inference of functional domain, no direct in vitro binding assay performed\",\n      \"pmids\": [\"7608277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Alanine substitution studies on rainbow trout MC2R identified V159 in TM4, F171 in TM5, and F175 in TM5 as critical residues for receptor activation by ACTH. A triple alanine mutant (V159A/F171A/F175A) could not be activated by ACTH at concentrations up to 10⁻⁶ M, while cell surface trafficking was unimpaired, pointing to a specific role for TM4 and TM5 in ACTH binding/activation rather than trafficking.\",\n      \"method\": \"Single and triple alanine mutagenesis of rtMC2R; cAMP assay; Cell Surface ELISA for trafficking\",\n      \"journal\": \"General and comparative endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic alanine mutagenesis with cAMP assay and surface ELISA to separate trafficking from activation, single lab\",\n      \"pmids\": [\"28495271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In rat bone marrow stromal cells, ACTH promotes chondrogenic nodule formation and induces transient elevations in intracellular calcium via MC2R signaling. Neither α-MSH (MC5R agonist) nor γ2-MSH (MC3R agonist) replicated these effects, and the cells express MC2R and MRAP by immunoblot, implicating MC2R specifically. Dexamethasone upregulates MC2R and MRAP expression, amplifying ACTH responses.\",\n      \"method\": \"Bone marrow stromal cell culture; MC-R-specific peptide agonists; immunoblot of membrane fractions; calcium flux assay; chondrogenic nodule quantification\",\n      \"journal\": \"Cell and tissue research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — pharmacological specificity approach without direct MC2R KO or knockdown confirmation, single lab\",\n      \"pmids\": [\"23358747\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MC2R from the Senegal bichir (Polypterus senegalus, a basal bony fish) requires Mrap1 (but not Mrap2) for membrane trafficking and ACTH-stimulated activation, and is selective for ACTH over α-MSH, demonstrating that Mrap1 dependence and ACTH selectivity are ancestral features of all bony fish Mc2rs.\",\n      \"method\": \"Heterologous co-expression in CHO cells; luciferase cAMP reporter assay; stimulation with ACTH and α-MSH; multiple vertebrate Mrap1 constructs tested\",\n      \"journal\": \"General and comparative endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reconstituted functional assay in CHO cells with multiple Mrap1 orthologs, single lab\",\n      \"pmids\": [\"35973587\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In a patient with familial glucocorticoid deficiency lacking skin hyperpigmentation, co-existing homozygous MC2R T152K (trafficking-defective) and MC1R R160W mutations were identified. This experimentally demonstrates that ACTH-driven MC1R activation is the cause of skin hyperpigmentation in FGD, as loss of MC1R function abolishes hyperpigmentation even in the context of severely elevated ACTH.\",\n      \"method\": \"Whole-gene sequencing; in vitro characterization of MC2R T152K as trafficking defective; clinical phenotype correlation\",\n      \"journal\": \"The Journal of clinical endocrinology and metabolism\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — natural experiment with genetic evidence but limited direct in vitro functional assay detail in abstract for MC2R specifically\",\n      \"pmids\": [\"22337906\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CRN04894 (17h), a nonpeptide MC2R antagonist derived from MC4R ligand modification, potently and selectively blocks MC2R and suppresses ACTH-stimulated corticosterone secretion in a dose-dependent manner in rats following oral administration, confirming the pharmacological tractability of MC2R as a drug target.\",\n      \"method\": \"Structure-activity relationship medicinal chemistry; in vivo rat ACTH-stimulated corticosterone assay; oral dosing at ≥3 mg/kg\",\n      \"journal\": \"ACS medicinal chemistry letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo pharmacological validation with selective antagonist, single study\",\n      \"pmids\": [\"38628803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CRISPR/Cas9-generated mc2r knockout zebrafish show impaired interrenal steroidogenesis and pronounced skin hyperpigmentation with increased numbers of melanophores and xanthophores (while preserving normal patterning), with transcriptomic upregulation of genes involved in melanosome formation, melanin synthesis, lipid metabolism, and carotenoid accumulation. This establishes a direct role for MC2R in steroidogenesis and in restraining pigment cell development.\",\n      \"method\": \"CRISPR/Cas9 mc2r knockout in zebrafish; histological quantification of pigment cells; transcriptomic analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined cellular and transcriptomic phenotypes, single study\",\n      \"pmids\": [\"41639367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In vitro study in HEK293 cells transfected with wild-type and MC2R mutant (p.Leu109Gln) plasmids showed defects in MC2R protein expression and cAMP generation upon ACTH stimulation, functionally confirming pathogenicity of this novel missense mutation.\",\n      \"method\": \"HEK293 cell transfection; cAMP assay; Western blot protein expression\",\n      \"journal\": \"Journal of the Endocrine Society\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single in vitro assay in a heterologous system, single lab, single variant\",\n      \"pmids\": [\"35506146\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MC2R (ACTHR) is a G protein-coupled receptor that selectively binds ACTH and signals via cAMP/PKA to drive adrenocortical steroidogenesis and pigment cell regulation; it requires the accessory protein MRAP1 for ACTH binding and functional cAMP signaling (though not for plasma membrane localization per se), undergoes PKA-dependent desensitization and GRK-dependent, arrestin/clathrin/dynamin-mediated internalization followed by Rab-mediated recycling, with ACTH-binding specificity mapped to TM4/TM5 and the second extracellular loop, intracellular retention signals in TM3/TM4, and transcriptional regulation driven cooperatively by SF-1, AP-1, PPARγ/RXRα (in adipocytes), FOXL2/NR5A1, and JDP2.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MC2R (the ACTH receptor) is a G protein-coupled receptor that drives adrenocortical steroidogenesis and restrains pigment cell development, as established by mc2r knockout in zebrafish, which impairs interrenal steroidogenesis and produces skin hyperpigmentation with expanded melanophore and xanthophore populations [#20]. Productive ACTH binding and cAMP signaling require the accessory protein MRAP, without which ACTH does not bind MC2R, even though MRAP is dispensable for plasma membrane localization per se; MRAP\\u03b2 confers higher cell-surface receptor density and maximal cAMP output than MRAP\\u03b1, and the MRAP isoforms' C-termini dictate their topology and subcellular localization to tune receptor targeting and signaling [#0, #8]. This MRAP1 dependence together with ACTH selectivity over \\u03b1-MSH is an ancestral feature conserved across bony fish [#17]. ACTH binding specificity and activation are governed by the fourth and fifth transmembrane domains and by an aromatic-residue-rich segment of the second extracellular loop, while intracellular retention signals reside in TM3/TM4 and the N-terminus modulates trafficking efficiency [#2, #3, #15]. Downstream, ACTH/MC2R signals through cAMP/PKA to activate p44/p42 and p38 MAPK [#5], drives PKA-dependent desensitization and GRK-dependent, arrestin/clathrin/dynamin-mediated internalization, followed by Rab4/5/11-dependent recycling that itself contributes to total cAMP accumulation [#1, #6]. Transcription of MC2R is controlled in a tissue-specific manner: SF-1 (NR5A1) cooperating with an AP-1 element drives adrenal-specific and cAMP-inducible expression [#9], FOXL2 synergizes with NR5A1 [#12], JDP2 acts as a cAMP-response-element-binding activator [#13], and a PPAR\\u03b3/RXR\\u03b1-bound PPRE mediates SF-1-independent expression in adipocytes [#10]. Loss-of-function MC2R mutations cause familial/isolated glucocorticoid deficiency, with separate variants disrupting ligand binding, cell-surface trafficking, or protein expression [#7, #14, #21].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Before any in vitro structure-function work, a patient mutation implicated specific receptor regions in ACTH binding and linked MC2R loss to disease.\",\n      \"evidence\": \"Direct sequencing of the intronless MC2R gene identifying a homozygous Y254C in the third extracellular loop in isolated glucocorticoid deficiency\",\n      \"pmids\": [\"7608277\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct in vitro binding assay performed\", \"Functional consequence inferred from topology, not measured\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Established how MC2R achieves adrenal-specific and cAMP-inducible expression, defining the core transcriptional logic of the receptor.\",\n      \"evidence\": \"5' deletion luciferase reporters, EMSA, and SF-1 overexpression/mutagenesis in Y1, JEG3, and Cos-1 cells\",\n      \"pmids\": [\"10811295\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"SF-1 alone insufficient in non-adrenal cells; additional co-factors needed\", \"Promoter context studied in cell lines, not endogenous chromatin\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Separated the kinases controlling MC2R desensitization versus internalization, distinguishing two regulatory arms of signaling termination.\",\n      \"evidence\": \"Y1/Y6 cell expression with kinase inhibitor studies and desensitization/internalization assays\",\n      \"pmids\": [\"12851305\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Which specific GRK acts on MC2R not identified\", \"Abstract-level mechanistic detail only\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identified a tissue-specific, SF-1-independent route to MC2R transcription, explaining adipocyte expression.\",\n      \"evidence\": \"5' deletion reporters in differentiating 3T3-L1 cells, EMSA with adipocyte nuclear extracts, PPAR\\u03b32/RXR\\u03b1 co-transfection and PPRE mutagenesis\",\n      \"pmids\": [\"15028712\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Studied in murine adipocyte model only\", \"Physiological role of adipocyte MC2R not established\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed that combinations of individually inactivating mutations can yield constitutive MC2R activity, revealing allele-level interaction effects.\",\n      \"evidence\": \"Stable expression of C21R/S247G single and double mutants in Y6 cells with cAMP accumulation and ligand binding assays\",\n      \"pmids\": [\"15062562\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of constitutive activation not resolved\", \"Clinical correlate of compound allele not established\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined repressive cis-regulation that prevents MC2R expression where SF-1 is present but the receptor should be silent.\",\n      \"evidence\": \"Luciferase reporters and EMSA in bovine adrenocortical versus granulosa cells\",\n      \"pmids\": [\"15171714\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single method type with limited mechanistic depth\", \"AP4 involvement not definitively established\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved the long-standing problem of MC2R functional reconstitution by showing MRAP is required for ACTH binding and signaling but not surface localization.\",\n      \"evidence\": \"Stable MC2R + MRAP\\u03b1/\\u03b2 expression in isogenic HEK293/FRT cells lacking endogenous MCRs, with binding, cAMP, surface density, and localization readouts\",\n      \"pmids\": [\"17456795\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which MRAP enables binding not resolved\", \"Stoichiometry of MC2R/MRAP complex not defined here\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Mapped the MC2R domains responsible for intracellular retention versus ACTH-binding selectivity, separating trafficking from ligand recognition.\",\n      \"evidence\": \"Systematic MC2R/MC4R chimeric constructs with confocal localization, ACTH(1-24) binding, and cAMP assays\",\n      \"pmids\": [\"20206229\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Residue-level binding contacts not defined\", \"No structural model of the binding pocket\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined the downstream effector cascade, showing MC2R activates MAPK strictly through cAMP/PKA and not via Epac or arrestin.\",\n      \"evidence\": \"HEK293/FRT cells expressing MC2R + MRAP\\u03b2 with pharmacological inhibitors, dominant-negative arrestin, and phospho-MAPK immunoblot\",\n      \"pmids\": [\"21195128\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream physiological output of MAPK activation not addressed\", \"Single cell system\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Showed that MRAP binding is insufficient for MC2R trafficking, identifying the C-terminus as an independent trafficking determinant in disease.\",\n      \"evidence\": \"OS3/cell surface expression assays, confocal localization, and co-IP of C-terminal mutants (K289fs, M290X) with MRAP\",\n      \"pmids\": [\"20962024\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"C-terminal trafficking motif not precisely defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Added FOXL2 to the transcriptional network controlling MC2R, demonstrating synergy with NR5A1.\",\n      \"evidence\": \"Mc2r promoter mapping and luciferase co-transfection with FOXL2 and NR5A1 in Y1 cells\",\n      \"pmids\": [\"20650879\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single assay type (reporter/co-transfection)\", \"Endogenous FOXL2 occupancy not shown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Characterized the full internalization/recycling itinerary of activated MC2R and showed recycling sustains cAMP output.\",\n      \"evidence\": \"HEK293/FRT cells with monensin/brefeldin A inhibitors, S/T residue mutagenesis, Rab GTPase colocalization, and cAMP assays\",\n      \"pmids\": [\"21920850\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Adaptor proteins linking MC2R to clathrin not identified\", \"Studied in heterologous cells, not adrenal cells\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined how MRAP1 isoform C-termini and membrane topology differentially tune MC2R localization and cAMP output.\",\n      \"evidence\": \"Stable expression in HEK293/FRT and B16-G4F cells with confocal imaging, topology assays, and cAMP accumulation\",\n      \"pmids\": [\"22366472\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional significance of dual topology in vivo unclear\", \"MRAP2 role only partially addressed\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Used a natural human double-mutant to prove that ACTH-driven MC1R activation, not MC2R itself, causes the skin hyperpigmentation seen in glucocorticoid deficiency.\",\n      \"evidence\": \"Whole-gene sequencing plus in vitro characterization of MC2R T152K as trafficking-defective with clinical phenotype correlation\",\n      \"pmids\": [\"22337906\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Limited in vitro functional detail for MC2R variant\", \"Single family\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Refined the structural basis of ACTH recognition, implicating the EC2 aromatic segment in engaging the second ACTH pharmacophore.\",\n      \"evidence\": \"Twenty segment-replacement (MC2R/MC4R) constructs with EGFP localization and cAMP assays\",\n      \"pmids\": [\"25074265\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct binding measurements, only functional readout\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Pinpointed individual TM4/TM5 residues required for ACTH activation while leaving trafficking intact, separating activation from surface delivery.\",\n      \"evidence\": \"Single and triple alanine mutagenesis of rainbow trout MC2R with cAMP assay and cell surface ELISA\",\n      \"pmids\": [\"28495271\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Demonstrated in fish ortholog; human residue conservation not directly tested\", \"No structural confirmation of contacts\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Added JDP2 as a CRE-binding transcriptional activator of Mc2r and showed its activity depends on phosphorylation and SUMOylation.\",\n      \"evidence\": \"Luciferase reporters, real-time ChIP, promoter deletion mapping, and phospho-/SUMO-deficient JDP2 mutants in Y1 cells\",\n      \"pmids\": [\"28146118\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Upstream signals controlling JDP2 modification in adrenal cells unclear\", \"Mouse promoter context\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established the evolutionary depth of MC2R's MRAP1 dependence and ACTH selectivity in a basal bony fish.\",\n      \"evidence\": \"Heterologous co-expression of Polypterus MC2R with multiple Mrap1 orthologs in CHO cells and luciferase cAMP reporter with ACTH and \\u03b1-MSH\",\n      \"pmids\": [\"35973587\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not address human-specific regulation\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Functionally confirmed pathogenicity of a novel disease missense variant through expression and signaling defects.\",\n      \"evidence\": \"HEK293 transfection of wild-type and p.Leu109Gln MC2R with cAMP assay and Western blot\",\n      \"pmids\": [\"35506146\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single in vitro assay in heterologous system\", \"Mechanism of defect (folding vs trafficking) not dissected\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Validated MC2R as a druggable target by demonstrating an orally active selective antagonist suppresses ACTH-driven steroid output in vivo.\",\n      \"evidence\": \"SAR medicinal chemistry yielding CRN04894 with in vivo rat ACTH-stimulated corticosterone assay after oral dosing\",\n      \"pmids\": [\"38628803\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding mode on MC2R not structurally defined\", \"Efficacy in disease models not shown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Provided in vivo genetic proof that MC2R is required for steroidogenesis and restrains pigment cell development.\",\n      \"evidence\": \"CRISPR/Cas9 mc2r knockout zebrafish with histological pigment cell quantification and transcriptomic analysis\",\n      \"pmids\": [\"41639367\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pigment phenotype mechanism (cell-autonomous vs systemic ACTH/MC1R) not dissected in this system\", \"Mammalian relevance of pigment role not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A high-resolution structure of the MC2R/MRAP/ACTH complex defining how MRAP enables ligand binding and how TM4/TM5 and EC2 contact ACTH remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No experimental structure of the activated complex\", \"Molecular mechanism of MRAP-dependent binding not defined\", \"Stoichiometry of MC2R:MRAP not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 1, 5]},\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [0, 2, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 8, 2]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [1, 8]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 5, 1]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [9, 10, 13]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"complexes\": [\"MC2R/MRAP1 receptor complex\"],\n    \"partners\": [\"MRAP\", \"MRAP2\", \"SF-1/NR5A1\", \"FOXL2\", \"JDP2\", \"PPARG\", \"RXRA\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":7,"faith_total":7,"faith_pct":100.0}}