{"gene":"SULT2A1","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2003,"finding":"Crystal structure of human DHEA-ST (SULT2A1) in complex with androsterone (ADT) solved at 2.7 Å, revealing that ADT binds with a different orientation than DHEA despite similar overall complex structure, and demonstrating that SULT2A1 catalyzes androsterone sulfation with similar kinetics but ~2-fold higher specificity and stronger substrate inhibition than DHEA.","method":"X-ray crystallography (2.7 Å), in vitro enzymatic kinetics with purified recombinant protein","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with functional kinetic validation in single rigorous study","pmids":["14573603"],"is_preprint":false},{"year":2007,"finding":"Active-site mutagenesis of SULT2A1 identified Tyr-238 and Met-137 as the two amino acids critical for substrate inhibition: Tyr-238 regulates release of bound substrate (Y238A mutation abolishes substrate inhibition for ADT and increases Ki for DHEA), while Met-137 controls substrate binding orientation of both DHEA and ADT. Crystal structures of Met-137 mutants confirmed these binding orientation changes.","method":"Site-directed mutagenesis, in vitro enzymatic assays, X-ray crystallography of mutant proteins","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis combined with crystal structure validation and kinetic assays in one study","pmids":["18042734"],"is_preprint":false},{"year":2014,"finding":"Complete quantitative kinetic mechanism of SULT2A1 determined: the mechanism comprises eight enzyme forms interconverting via 22 rate constants, each determined independently, providing a full description of sulfuryl transfer from PAPS to acceptor hydroxyls/amines.","method":"Comprehensive kinetic analysis with independently determined rate constants; in vitro enzymatic assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — thorough in vitro mechanistic dissection with multiple independently determined parameters in one rigorous study","pmids":["25056952"],"is_preprint":false},{"year":2010,"finding":"SULT2A1 functions as a homodimer; a monomeric MBP-SULT2A1 fusion protein retains similar Km and Vmax for DHEA but lacks substrate inhibition. Intrinsic fluorescence showed two DHEA molecules bind each subunit (one catalytic, one allosteric); dimerization increases DHEA binding at the allosteric site, which is responsible for substrate inhibition.","method":"Size exclusion chromatography, intrinsic fluorescence binding assays, initial-rate kinetics with purified recombinant protein","journal":"Hormone molecular biology and clinical investigation","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal methods (chromatography, fluorescence, kinetics) in single study; replicated in two publications (PMIDs 21822453 and 25961208)","pmids":["21822453","25961208"],"is_preprint":false},{"year":2010,"finding":"Substrate inhibition of SULT2A1 by DHEA is mechanistically explained by formation of non-productive ternary dead-end complexes involving the nucleotide product PAP; equilibrium binding and initial velocity studies showed negative cooperativity in DHEA binding, consistent with involvement of both DHEA and DHEA-sulfate in these complexes.","method":"Initial velocity studies, equilibrium binding assays, in vitro enzymatic assays with purified recombinant hSULT2A1","journal":"Archives of biochemistry and biophysics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal methods (kinetics + binding), single lab","pmids":["21187059"],"is_preprint":false},{"year":2018,"finding":"SULT2A1 physically interacts with PAPS synthase 2 (PAPSS2) but only weakly with PAPSS1, as demonstrated by proximity ligation assay; molecular docking identified a putative binding site for SULT2A1 within the PAPSS2 APS kinase domain. Knockdown experiments confirmed PAPSS2, but not PAPSS1, is required for efficient DHEA sulfation in adrenocortical NCI-H295R1 cells, establishing a direct protein–protein interaction underlying selective PAPS channeling to SULT2A1.","method":"Proximity ligation assay, siRNA knockdown in NCI-H295R1 cells, molecular docking","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proximity ligation assay + functional knockdown + docking, single lab","pmids":["29743239"],"is_preprint":false},{"year":2002,"finding":"Three non-synonymous coding SNPs in SULT2A1 (found in African-American subjects) significantly decrease enzyme activity; decreased immunoreactive protein levels are the major mechanism, though apparent Km values also vary. One variant disrupts the dimerization interface causing the allozyme to behave as a monomer by gel filtration.","method":"Heterologous expression in COS-1 cells, Western blot, gel filtration chromatography, enzyme activity assays","journal":"The pharmacogenomics journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (expression, Western blot, chromatography, activity), single lab","pmids":["11990382"],"is_preprint":false},{"year":2010,"finding":"SULT2A1 sulfates 15 human bile acids with Michaelis–Menten kinetics; sulfation affinity (Km) is inversely proportional to the number of hydroxyl groups—lithocholic acid (monohydroxy) shows highest affinity and cholic acid (trihydroxy) the lowest. DHEA sulfation Km = 3.8 µM, Vmax = 130.8 pmol/min/mg in stably transfected HEK293 cells.","method":"Stable HEK293 cell expression system, kinetic enzymatic assays","journal":"Xenobiotica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic kinetic characterization with stable cell line, single lab","pmids":["20102295"],"is_preprint":false},{"year":2009,"finding":"SULT2A1 is the sole human cytosolic sulfotransferase responsible for N-sulfoconjugation of quinolone drugs (ciprofloxacin, moxifloxacin, garenoxacin) and other amine-containing drugs (desipramine, metoclopramide); the other five SULT isoforms tested showed no activity. Human liver cytosol N-sulfation kinetics were monophasic with Km values matching those of recombinant SULT2A1.","method":"In vitro enzymatic assays with purified recombinant SULTs and human liver cytosols, kinetic analysis","journal":"Drug metabolism and disposition","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — recombinant enzyme panel + human liver cytosol correlation, single lab","pmids":["19420132"],"is_preprint":false},{"year":2005,"finding":"Vitamin D receptor (VDR) induces SULT2A1 transcription through a composite element containing an imperfect inverted-repeat VDRE and a C/EBP-alpha binding site 9 bp downstream. C/EBP-alpha is essential for this induction: mutations abolish induction, C/EBP-alpha-deficient cells require cotransfected C/EBP-alpha, and C/EBP-beta cannot substitute. VDR and C/EBP-alpha form a DNA-dependent, coimmunoprecipitable complex at the element, with concurrent recruitment of coactivators p300, SRC-1, and SRC-2 (but not SRC-3).","method":"Reporter gene assays, EMSA, DNase I footprinting, antibody supershift, chromatin immunoprecipitation (ChIP), co-immunoprecipitation, site-directed mutagenesis","journal":"Molecular endocrinology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (ChIP, EMSA, mutagenesis, Co-IP) establishing mechanistic regulation","pmids":["16357103"],"is_preprint":false},{"year":2007,"finding":"HNF4α plays a central role in SULT2A1 transcription: two HNF4α-binding sites in the SULT2A1 5'-flanking region (-6160 and -54) were identified by in vitro binding and site-directed mutagenesis; HNF4α binds the endogenous gene (confirmed by ChIP). Rifampicin-activated PXR suppresses SULT2A1 by interfering with HNF4α activity; PXR knockdown by RNAi diminished this suppression.","method":"Transient transfection reporter assays, in vitro binding, site-directed mutagenesis, ChIP, siRNA knockdown in HepG2 cells, primary human hepatocytes","journal":"The Journal of pharmacology and experimental therapeutics","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — ChIP, mutagenesis, RNAi, and primary hepatocyte validation, multiple orthogonal methods","pmids":["17687072"],"is_preprint":false},{"year":2005,"finding":"Estrogen-related receptor alpha (ERRα) activates SULT2A1 transcription in adrenal cells: three functional ERRα-binding cis-elements (sharing SF1 similarity) were identified in the SULT2A1 5'-flanking region by serial deletion and EMSA; ERRα stimulated SULT2A1 promoter activity more strongly than SF1.","method":"Reporter gene assays, EMSA, serial deletion analysis, cotransfection experiments","journal":"Endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reporter + EMSA, single lab","pmids":["15878968"],"is_preprint":false},{"year":2012,"finding":"RORα and RORγ transactivate SULT2A1 gene expression through a ROR response element in the SULT2A1 promoter (overlapping with a previously identified CAR response element), as demonstrated by reporter assays, EMSA, and ChIP; siRNA knockdown of RORα/RORγ reduced endogenous SULT2A1 expression in human hepatocytes.","method":"Promoter reporter assays, EMSA, ChIP, siRNA knockdown in primary human hepatocytes","journal":"Molecular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple methods (ChIP, EMSA, siRNA, reporter), single lab","pmids":["23211525"],"is_preprint":false},{"year":2014,"finding":"LXRα (NR1H3) transactivates SULT2A1 via specific binding to the -500 to -258 bp region of the SULT2A1 promoter; LXRα siRNA knockdown showed LXRα, but not LXRβ, dominantly regulates SULT2A1 expression at mRNA, protein, and enzymatic levels.","method":"Promoter reporter assays, ChIP, siRNA knockdown, enzyme activity assays in HepG2 cells and primary human hepatocytes","journal":"Drug metabolism and disposition","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP + reporter + siRNA, single lab","pmids":["25028566"],"is_preprint":false},{"year":2011,"finding":"ERRα represses SULT2A1 promoter transcription in HepG2 cells through two ERRα response elements (ERRE188 and ERRE155) in the -188 to -130 bp region that overlap with IR2 and DR4 nuclear receptor elements; ERRα competes with other nuclear receptors for binding to these elements, confirmed by EMSA and ChIP.","method":"Reporter gene assays with deletion analysis, EMSA, ChIP in HepG2 cells","journal":"Chemico-biological interactions","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — EMSA + ChIP + reporter with mutagenesis, single lab","pmids":["21513704"],"is_preprint":false},{"year":2019,"finding":"hsa-miR-495-3p and hsa-miR-486-5p post-transcriptionally suppress SULT2A1 expression by binding directly to miRNA response elements in the SULT2A1 3'-UTR and decreasing mRNA stability; this was demonstrated by RNA EMSA, luciferase reporter assays, and gain/loss-of-function experiments in HepG2 cells.","method":"Fluorescence-based RNA EMSA, luciferase reporter assays, miRNA overexpression/inhibition in HepG2 cells","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (EMSA, reporter, gain/loss-of-function), single lab","pmids":["31445882"],"is_preprint":false},{"year":2006,"finding":"Hydroxylated PCB metabolites (OHPCBs) act as both substrates and inhibitors of purified recombinant SULT2A1: 4-OH PCB 34 and 4'-OH PCB 68 are substrates (with 4-OH PCB 34 showing substrate inhibition similar to DHEA), while 4'-OH PCB 9 is an inhibitor but not a substrate.","method":"In vitro enzymatic assays with purified recombinant SULT2A1","journal":"Chemical research in toxicology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — purified recombinant enzyme assays with multiple substrates/inhibitors, single lab","pmids":["17112228"],"is_preprint":false},{"year":2004,"finding":"During the LPS-induced acute-phase response in mice, hepatic Sult2A1 mRNA and enzyme activity are suppressed in a time- and dose-dependent manner, accompanied by decreased serum DHEA-S; TNF and IL-1 mediate this suppression in human Hep3B cells, suggesting that inflammatory cytokine-driven suppression of FXR/PXR/CAR leads to decreased SULT2A1-mediated DHEA sulfation.","method":"LPS treatment in mice, RT-PCR, enzyme activity assay, serum steroid measurement, cytokine treatment of Hep3B cells","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo and in vitro convergent evidence, single lab","pmids":["15198932"],"is_preprint":false},{"year":2010,"finding":"Glycyrrhetinic acid (the active component of liquorice) directly inhibits adrenal SULT2A1 activity with an IC50 of ~7 µM, decreasing sulfoconjugation of DHEA and deoxycorticosterone in adrenocortical H295 cells without altering SULT2A1 mRNA levels, increasing free DHEA and deoxycorticosterone.","method":"Adrenocortical H295 cell incubations, radiolabeled steroid conjugation assays, mRNA analysis","journal":"Molecular and cellular endocrinology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based activity assay + mRNA measurement, single lab","pmids":["21184804"],"is_preprint":false},{"year":2021,"finding":"Metformin suppresses CAR-induced (but not basal) SULT2A1 expression by blocking CAR nuclear translocation via an AMPK-dependent mechanism in HepaRG cells.","method":"Western blot, cell viability assay, nuclear fractionation, HepaRG cell model with pharmacological activators/inhibitors","journal":"International journal of endocrinology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, Western blot and fractionation without orthogonal mechanistic validation","pmids":["33643408"],"is_preprint":false},{"year":2014,"finding":"Dopamine D1 receptor (DRD1) activation in HepG2 cells upregulates SULT2A1 mRNA, protein, and enzyme activity via elevated cAMP; this effect is partially blocked by DRD1 antagonist SCH23390 and reduced by DRD1-specific siRNA knockdown.","method":"RT-PCR, Western blot, HPLC enzyme activity assay, cAMP measurement, siRNA knockdown in HepG2 cells","journal":"Acta pharmacologica Sinica","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect pathway evidence without promoter-level mechanistic detail","pmids":["24909515"],"is_preprint":false},{"year":2004,"finding":"Alpha-hydroxytamoxifen (alpha-OHTAM) stereoisomers are all substrates for human SULT2A1 (unlike rat STa where only one enantiomer is a substrate); Z-enantiomers show higher kcat/Km values with SULT2A1 than E-enantiomers, demonstrating stereospecificity in SULT2A1-catalyzed sulfation.","method":"In vitro enzymatic assays with highly purified recombinant SULT2A1, kinetic analysis of stereoisomers","journal":"Drug metabolism and disposition","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — purified recombinant enzyme with systematic stereoisomer kinetics, single lab","pmids":["15371299"],"is_preprint":false}],"current_model":"SULT2A1 (DHEA-ST) is a cytosolic hydroxysteroid sulfotransferase that functions as a homodimer to catalyze PAPS-dependent sulfonation of DHEA, androsterone, bile acids (with highest affinity for toxic monohydroxy species such as lithocholic acid), and a range of xenobiotics including quinolone drugs and hydroxylated PCBs; substrate inhibition arises from DHEA binding at a dimerization-dependent allosteric site (governed by Tyr-238 and Met-137), and efficient DHEA sulfation requires direct protein–protein interaction between SULT2A1 and PAPSS2 (but not PAPSS1); transcription is regulated by multiple nuclear receptors (VDR, FXR, PXR, CAR, RORα/γ, LXRα, HNF4α, ERRα) and post-transcriptionally suppressed by miR-495-3p and miR-486-5p, while inflammatory cytokines (TNF, IL-1) and metformin (via AMPK-CAR axis) downregulate its expression."},"narrative":{"mechanistic_narrative":"SULT2A1 is a cytosolic hydroxysteroid sulfotransferase that catalyzes PAPS-dependent sulfonation of steroid hormones, bile acids, and amine- and hydroxyl-containing xenobiotics, functioning as the principal enzyme for steroid and drug sulfoconjugation in liver and adrenal tissue [PMID:14573603, PMID:20102295, PMID:19420132]. Its catalytic cycle has been resolved as an eight-form kinetic mechanism transferring the sulfuryl group from PAPS to acceptor hydroxyls and amines [PMID:25056952], and crystal structures with androsterone and DHEA show that closely related substrates adopt distinct binding orientations governed by active-site residues [PMID:14573603]. SULT2A1 acts as a homodimer in which each subunit carries a catalytic and an allosteric DHEA-binding site; dimerization enhances allosteric DHEA binding and produces the characteristic substrate inhibition, which is mechanistically explained by non-productive dead-end ternary complexes with the nucleotide product PAP and which depends on residues Tyr-238 (substrate release) and Met-137 (binding orientation) [PMID:18042734, PMID:21822453, PMID:25961208, PMID:21187059]. Efficient cellular DHEA sulfation further requires a direct protein-protein interaction between SULT2A1 and PAPSS2, but not PAPSS1, channeling PAPS to the enzyme [PMID:29743239]. The substrate repertoire spans DHEA, androsterone, and a graded series of bile acids whose affinity rises as hydroxylation falls—lithocholic acid being the highest-affinity acceptor [PMID:14573603, PMID:20102295]—as well as quinolone and other amine drugs for which SULT2A1 is the sole responsible human SULT [PMID:19420132], stereoisomers of alpha-hydroxytamoxifen [PMID:15371299], and hydroxylated PCB metabolites that serve as both substrates and inhibitors [PMID:17112228]. SULT2A1 transcription is controlled by a network of nuclear receptors—including VDR acting with C/EBP-alpha, HNF4alpha (antagonized by PXR), ERRalpha, RORalpha/gamma, and LXRalpha [PMID:16357103, PMID:17687072, PMID:15878968, PMID:23211525, PMID:25028566]—and is post-transcriptionally suppressed by miR-495-3p and miR-486-5p and downregulated by inflammatory cytokines TNF and IL-1 [PMID:31445882, PMID:15198932].","teleology":[{"year":2002,"claim":"Establishing that natural coding variation alters SULT2A1 function showed both protein abundance and dimerization as determinants of enzyme activity, defining a pharmacogenetic basis for inter-individual differences.","evidence":"Heterologous expression of coding SNP allozymes in COS-1 cells with Western blot, gel filtration, and activity assays","pmids":["11990382"],"confidence":"Medium","gaps":["Phenotypic consequences in vivo not established","Allele frequencies and clinical correlation outside studied population unknown"]},{"year":2003,"claim":"The first crystal structure with androsterone answered how SULT2A1 accommodates structurally similar steroids, revealing distinct substrate orientations and differing kinetics for androsterone versus DHEA.","evidence":"X-ray crystallography at 2.7 Å plus in vitro kinetics of purified recombinant enzyme","pmids":["14573603"],"confidence":"High","gaps":["Structural basis of substrate inhibition not resolved from this structure alone","Dimer-level allostery not captured"]},{"year":2004,"claim":"Inflammatory suppression of SULT2A1 linked the enzyme to acute-phase regulation of circulating steroid sulfates, showing cytokine control over DHEA sulfation capacity.","evidence":"LPS challenge in mice plus TNF/IL-1 treatment of Hep3B cells with RT-PCR, activity, and serum steroid measurement","pmids":["15198932"],"confidence":"Medium","gaps":["Direct promoter/transcription-factor target of cytokine signaling not mapped","Reliance on mouse Sult2A1 for in vivo arm"]},{"year":2005,"claim":"Identification of VDR/C-EBP-alpha and ERRalpha cis-elements established that SULT2A1 transcription is directed by combinatorial nuclear-receptor inputs in hepatic and adrenal contexts.","evidence":"Reporter assays, EMSA, DNase footprinting, ChIP, and Co-IP for VDR/C-EBP-alpha; reporter and EMSA for ERRalpha","pmids":["16357103","15878968"],"confidence":"High","gaps":["Relative contribution of each receptor in physiological tissue not quantified","Endogenous coactivator stoichiometry undefined"]},{"year":2007,"claim":"Defining HNF4alpha as a central activator antagonized by PXR clarified how xenobiotic-sensing signaling reshapes hepatic SULT2A1 expression.","evidence":"Reporter assays, in vitro binding, mutagenesis, ChIP, and siRNA in HepG2 cells and primary human hepatocytes","pmids":["17687072"],"confidence":"High","gaps":["Mechanism by which PXR interferes with HNF4alpha activity not fully defined","Interplay with other identified receptors not integrated"]},{"year":2009,"claim":"Demonstrating SULT2A1 as the unique human SULT for quinolone N-sulfoconjugation extended its role from steroid metabolism to drug detoxification.","evidence":"Recombinant SULT panel and human liver cytosol kinetic correlation","pmids":["19420132"],"confidence":"Medium","gaps":["In vivo pharmacokinetic relevance not established","Toxicological consequences of N-sulfo metabolites unaddressed"]},{"year":2010,"claim":"Multiple studies resolved the homodimeric, allosterically inhibited architecture: a monomeric fusion lacks substrate inhibition, two DHEA sites exist per subunit, and inhibition arises from PAP-containing dead-end complexes, explaining the enzyme's nonlinear kinetics.","evidence":"Size-exclusion chromatography, intrinsic fluorescence, and initial-velocity/equilibrium binding studies with purified recombinant enzyme","pmids":["21822453","25961208","21187059"],"confidence":"High","gaps":["Physiological significance of substrate inhibition in vivo unclear","Structural snapshot of the allosteric DHEA-bound dimer not solved"]},{"year":2010,"claim":"Systematic bile-acid kinetics established that sulfation affinity scales inversely with hydroxyl number, positioning SULT2A1 to preferentially detoxify the most hydrophobic, toxic monohydroxy bile acids.","evidence":"Stable HEK293 expression with kinetic enzymatic assays across 15 bile acids","pmids":["20102295"],"confidence":"Medium","gaps":["In vivo contribution to bile-acid homeostasis not measured","Competition with steroid substrates not assessed"]},{"year":2011,"claim":"Discovery that ERRalpha can also repress the SULT2A1 promoter by competing at overlapping nuclear-receptor elements revealed context-dependent, bidirectional control of the gene.","evidence":"Reporter deletion assays, EMSA, and ChIP in HepG2 cells","pmids":["21513704"],"confidence":"Medium","gaps":["Reconciliation of activating versus repressing ERRalpha roles across tissues unresolved","Competing factors at the overlapping elements not all identified"]},{"year":2012,"claim":"RORalpha/gamma and LXRalpha were added as activators acting through promoter elements, broadening the lipid/sterol-sensing receptor network governing SULT2A1.","evidence":"Reporter assays, EMSA, ChIP, and siRNA in HepG2 cells and primary human hepatocytes (RORalpha/gamma 2012; LXRalpha 2014)","pmids":["23211525","25028566"],"confidence":"Medium","gaps":["Hierarchy among the overlapping ROR/CAR and other receptor elements not resolved","Ligand-dependence in vivo not established"]},{"year":2007,"claim":"Mutagenesis pinpointed Tyr-238 and Met-137 as the residues governing substrate inhibition, assigning specific structural determinants to substrate release and binding orientation.","evidence":"Site-directed mutagenesis, kinetic assays, and crystal structures of Met-137 mutants","pmids":["18042734"],"confidence":"High","gaps":["Link between these residues and the dimer-dependent allosteric site not structurally co-resolved"]},{"year":2014,"claim":"A complete eight-form, 22-rate-constant kinetic mechanism provided a quantitative description of sulfuryl transfer, anchoring all prior phenomenological kinetics in a unified scheme.","evidence":"Comprehensive in vitro kinetic analysis with independently determined rate constants","pmids":["25056952"],"confidence":"High","gaps":["Mechanism derived in vitro; cellular PAPS channeling not incorporated","Allosteric inhibition not embedded in the scheme"]},{"year":2018,"claim":"Identifying a direct SULT2A1-PAPSS2 interaction explained selective sulfodonor channeling, connecting cofactor supply physically to the sulfotransferase.","evidence":"Proximity ligation assay, siRNA knockdown in NCI-H295R1 cells, and molecular docking","pmids":["29743239"],"confidence":"Medium","gaps":["Interaction not confirmed by reciprocal structural or co-purification methods","Docked binding site not experimentally validated"]},{"year":2019,"claim":"Identification of miR-495-3p and miR-486-5p added a post-transcriptional layer of SULT2A1 control through 3'-UTR binding and mRNA destabilization.","evidence":"RNA EMSA, luciferase reporter, and miRNA gain/loss-of-function in HepG2 cells","pmids":["31445882"],"confidence":"Medium","gaps":["In vivo regulatory relevance not shown","Upstream signals controlling these miRNAs unknown"]},{"year":2021,"claim":"Pharmacological inputs (metformin via AMPK-CAR, dopamine D1 receptor via cAMP) were shown to modulate SULT2A1, extending its regulation to drug- and signaling-driven contexts.","evidence":"HepaRG metformin study with nuclear fractionation; HepG2 DRD1 study with RT-PCR, Western blot, cAMP, and siRNA (2014)","pmids":["33643408","24909515"],"confidence":"Low","gaps":["Single-lab studies without orthogonal mechanistic validation","Promoter-level targets of these signals not mapped","In vivo relevance unestablished"]},{"year":null,"claim":"How the in vitro allosteric/substrate-inhibition mechanism and the PAPSS2-channeled, nuclear-receptor- and miRNA-regulated cellular state integrate to set tissue-specific steroid and bile-acid sulfation flux in vivo remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the allosteric DHEA-bound dimer","PAPSS2 interaction lacks structural confirmation","Physiological consequence of substrate inhibition unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,2,7,8]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[8]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[7,18]},{"term_id":"R-HSA-9748784","term_label":"Drug ADME","supporting_discovery_ids":[8,21]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[9,10,12,13]}],"complexes":[],"partners":["PAPSS2","HNF4A","VDR","CEBPA","ESRRA","RORA","RORC","NR1H3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q06520","full_name":"Sulfotransferase 2A1","aliases":["Bile salt sulfotransferase","Dehydroepiandrosterone sulfotransferase","DHEA-ST","DHEA-ST8","Hydroxysteroid Sulfotransferase","HST","ST2","SULT2A3"],"length_aa":285,"mass_kda":33.8,"function":"Sulfotransferase that utilizes 3'-phospho-5'-adenylyl sulfate (PAPS) as sulfonate donor to catalyze the sulfonation of steroids and bile acids in the liver and adrenal glands (PubMed:14573603, PubMed:18042734, PubMed:19589875, PubMed:20102295, PubMed:21187059, PubMed:2268288, PubMed:29671343, PubMed:7678732, PubMed:7854148). Mediates the sulfation of a wide range of steroids and sterols, including pregnenolone, androsterone, DHEA, bile acids, cholesterol and as well many xenobiotics that contain alcohol and phenol functional groups (PubMed:14573603, PubMed:18042734, PubMed:19589875, PubMed:20102295, PubMed:21187059, PubMed:2268288, PubMed:29671343, PubMed:7678732, PubMed:7854148). Sulfonation increases the water solubility of most compounds, and therefore their renal excretion, but it can also result in bioactivation to form active metabolites. Plays an important role in maintening steroid and lipid homeostasis (PubMed:14573603, PubMed:19589875, PubMed:21187059). Plays a key role in bile acid metabolism, mediating formation of 3-sulfated bile acids (PubMed:2268288, PubMed:20102295). In addition, catalyzes the metabolic activation of potent carcinogenic polycyclic arylmethanols (By similarity)","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q06520/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SULT2A1","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/SULT2A1","total_profiled":1310},"omim":[{"mim_id":"604125","title":"SULFOTRANSFERASE FAMILY 2B, MEMBER 1; SULT2B1","url":"https://www.omim.org/entry/604125"},{"mim_id":"184700","title":"POLYCYSTIC OVARY SYNDROME 1; PCOS1","url":"https://www.omim.org/entry/184700"},{"mim_id":"125263","title":"SULFOTRANSFERASE FAMILY 2A, DEHYDROEPIANDROSTERONE-PREFERRING, MEMBER 1; SULT2A1","url":"https://www.omim.org/entry/125263"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"liver","ntpm":1005.4}],"url":"https://www.proteinatlas.org/search/SULT2A1"},"hgnc":{"alias_symbol":["DHEA-ST"],"prev_symbol":["STD"]},"alphafold":{"accession":"Q06520","domains":[{"cath_id":"3.40.50.300","chopping":"5-280","consensus_level":"high","plddt":96.0679,"start":5,"end":280}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q06520","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q06520-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q06520-F1-predicted_aligned_error_v6.png","plddt_mean":95.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SULT2A1","jax_strain_url":"https://www.jax.org/strain/search?query=SULT2A1"},"sequence":{"accession":"Q06520","fasta_url":"https://rest.uniprot.org/uniprotkb/Q06520.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q06520/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q06520"}},"corpus_meta":[{"pmid":"15198932","id":"PMC_15198932","title":"Suppression of DHEA sulfotransferase (Sult2A1) during the acute-phase response.","date":"2004","source":"American journal of physiology. Endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/15198932","citation_count":76,"is_preprint":false},{"pmid":"16399349","id":"PMC_16399349","title":"Vitamin D receptor regulation of the steroid/bile acid sulfotransferase SULT2A1.","date":"2005","source":"Methods in enzymology","url":"https://pubmed.ncbi.nlm.nih.gov/16399349","citation_count":72,"is_preprint":false},{"pmid":"11990382","id":"PMC_11990382","title":"Human sulfotransferase SULT2A1 pharmacogenetics: genotype-to-phenotype studies.","date":"2002","source":"The pharmacogenomics journal","url":"https://pubmed.ncbi.nlm.nih.gov/11990382","citation_count":70,"is_preprint":false},{"pmid":"12923182","id":"PMC_12923182","title":"Crystal structure of human cholesterol sulfotransferase (SULT2B1b) in the presence of pregnenolone and 3'-phosphoadenosine 5'-phosphate. 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Crystal structures of Met-137 mutants confirmed these binding orientation changes.\",\n      \"method\": \"Site-directed mutagenesis, in vitro enzymatic assays, X-ray crystallography of mutant proteins\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis combined with crystal structure validation and kinetic assays in one study\",\n      \"pmids\": [\"18042734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Complete quantitative kinetic mechanism of SULT2A1 determined: the mechanism comprises eight enzyme forms interconverting via 22 rate constants, each determined independently, providing a full description of sulfuryl transfer from PAPS to acceptor hydroxyls/amines.\",\n      \"method\": \"Comprehensive kinetic analysis with independently determined rate constants; in vitro enzymatic assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — thorough in vitro mechanistic dissection with multiple independently determined parameters in one rigorous study\",\n      \"pmids\": [\"25056952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"SULT2A1 functions as a homodimer; a monomeric MBP-SULT2A1 fusion protein retains similar Km and Vmax for DHEA but lacks substrate inhibition. Intrinsic fluorescence showed two DHEA molecules bind each subunit (one catalytic, one allosteric); dimerization increases DHEA binding at the allosteric site, which is responsible for substrate inhibition.\",\n      \"method\": \"Size exclusion chromatography, intrinsic fluorescence binding assays, initial-rate kinetics with purified recombinant protein\",\n      \"journal\": \"Hormone molecular biology and clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal methods (chromatography, fluorescence, kinetics) in single study; replicated in two publications (PMIDs 21822453 and 25961208)\",\n      \"pmids\": [\"21822453\", \"25961208\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Substrate inhibition of SULT2A1 by DHEA is mechanistically explained by formation of non-productive ternary dead-end complexes involving the nucleotide product PAP; equilibrium binding and initial velocity studies showed negative cooperativity in DHEA binding, consistent with involvement of both DHEA and DHEA-sulfate in these complexes.\",\n      \"method\": \"Initial velocity studies, equilibrium binding assays, in vitro enzymatic assays with purified recombinant hSULT2A1\",\n      \"journal\": \"Archives of biochemistry and biophysics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal methods (kinetics + binding), single lab\",\n      \"pmids\": [\"21187059\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SULT2A1 physically interacts with PAPS synthase 2 (PAPSS2) but only weakly with PAPSS1, as demonstrated by proximity ligation assay; molecular docking identified a putative binding site for SULT2A1 within the PAPSS2 APS kinase domain. Knockdown experiments confirmed PAPSS2, but not PAPSS1, is required for efficient DHEA sulfation in adrenocortical NCI-H295R1 cells, establishing a direct protein–protein interaction underlying selective PAPS channeling to SULT2A1.\",\n      \"method\": \"Proximity ligation assay, siRNA knockdown in NCI-H295R1 cells, molecular docking\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proximity ligation assay + functional knockdown + docking, single lab\",\n      \"pmids\": [\"29743239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Three non-synonymous coding SNPs in SULT2A1 (found in African-American subjects) significantly decrease enzyme activity; decreased immunoreactive protein levels are the major mechanism, though apparent Km values also vary. One variant disrupts the dimerization interface causing the allozyme to behave as a monomer by gel filtration.\",\n      \"method\": \"Heterologous expression in COS-1 cells, Western blot, gel filtration chromatography, enzyme activity assays\",\n      \"journal\": \"The pharmacogenomics journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (expression, Western blot, chromatography, activity), single lab\",\n      \"pmids\": [\"11990382\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"SULT2A1 sulfates 15 human bile acids with Michaelis–Menten kinetics; sulfation affinity (Km) is inversely proportional to the number of hydroxyl groups—lithocholic acid (monohydroxy) shows highest affinity and cholic acid (trihydroxy) the lowest. DHEA sulfation Km = 3.8 µM, Vmax = 130.8 pmol/min/mg in stably transfected HEK293 cells.\",\n      \"method\": \"Stable HEK293 cell expression system, kinetic enzymatic assays\",\n      \"journal\": \"Xenobiotica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic kinetic characterization with stable cell line, single lab\",\n      \"pmids\": [\"20102295\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SULT2A1 is the sole human cytosolic sulfotransferase responsible for N-sulfoconjugation of quinolone drugs (ciprofloxacin, moxifloxacin, garenoxacin) and other amine-containing drugs (desipramine, metoclopramide); the other five SULT isoforms tested showed no activity. Human liver cytosol N-sulfation kinetics were monophasic with Km values matching those of recombinant SULT2A1.\",\n      \"method\": \"In vitro enzymatic assays with purified recombinant SULTs and human liver cytosols, kinetic analysis\",\n      \"journal\": \"Drug metabolism and disposition\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — recombinant enzyme panel + human liver cytosol correlation, single lab\",\n      \"pmids\": [\"19420132\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Vitamin D receptor (VDR) induces SULT2A1 transcription through a composite element containing an imperfect inverted-repeat VDRE and a C/EBP-alpha binding site 9 bp downstream. C/EBP-alpha is essential for this induction: mutations abolish induction, C/EBP-alpha-deficient cells require cotransfected C/EBP-alpha, and C/EBP-beta cannot substitute. VDR and C/EBP-alpha form a DNA-dependent, coimmunoprecipitable complex at the element, with concurrent recruitment of coactivators p300, SRC-1, and SRC-2 (but not SRC-3).\",\n      \"method\": \"Reporter gene assays, EMSA, DNase I footprinting, antibody supershift, chromatin immunoprecipitation (ChIP), co-immunoprecipitation, site-directed mutagenesis\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (ChIP, EMSA, mutagenesis, Co-IP) establishing mechanistic regulation\",\n      \"pmids\": [\"16357103\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"HNF4α plays a central role in SULT2A1 transcription: two HNF4α-binding sites in the SULT2A1 5'-flanking region (-6160 and -54) were identified by in vitro binding and site-directed mutagenesis; HNF4α binds the endogenous gene (confirmed by ChIP). Rifampicin-activated PXR suppresses SULT2A1 by interfering with HNF4α activity; PXR knockdown by RNAi diminished this suppression.\",\n      \"method\": \"Transient transfection reporter assays, in vitro binding, site-directed mutagenesis, ChIP, siRNA knockdown in HepG2 cells, primary human hepatocytes\",\n      \"journal\": \"The Journal of pharmacology and experimental therapeutics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — ChIP, mutagenesis, RNAi, and primary hepatocyte validation, multiple orthogonal methods\",\n      \"pmids\": [\"17687072\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Estrogen-related receptor alpha (ERRα) activates SULT2A1 transcription in adrenal cells: three functional ERRα-binding cis-elements (sharing SF1 similarity) were identified in the SULT2A1 5'-flanking region by serial deletion and EMSA; ERRα stimulated SULT2A1 promoter activity more strongly than SF1.\",\n      \"method\": \"Reporter gene assays, EMSA, serial deletion analysis, cotransfection experiments\",\n      \"journal\": \"Endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reporter + EMSA, single lab\",\n      \"pmids\": [\"15878968\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RORα and RORγ transactivate SULT2A1 gene expression through a ROR response element in the SULT2A1 promoter (overlapping with a previously identified CAR response element), as demonstrated by reporter assays, EMSA, and ChIP; siRNA knockdown of RORα/RORγ reduced endogenous SULT2A1 expression in human hepatocytes.\",\n      \"method\": \"Promoter reporter assays, EMSA, ChIP, siRNA knockdown in primary human hepatocytes\",\n      \"journal\": \"Molecular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple methods (ChIP, EMSA, siRNA, reporter), single lab\",\n      \"pmids\": [\"23211525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LXRα (NR1H3) transactivates SULT2A1 via specific binding to the -500 to -258 bp region of the SULT2A1 promoter; LXRα siRNA knockdown showed LXRα, but not LXRβ, dominantly regulates SULT2A1 expression at mRNA, protein, and enzymatic levels.\",\n      \"method\": \"Promoter reporter assays, ChIP, siRNA knockdown, enzyme activity assays in HepG2 cells and primary human hepatocytes\",\n      \"journal\": \"Drug metabolism and disposition\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP + reporter + siRNA, single lab\",\n      \"pmids\": [\"25028566\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ERRα represses SULT2A1 promoter transcription in HepG2 cells through two ERRα response elements (ERRE188 and ERRE155) in the -188 to -130 bp region that overlap with IR2 and DR4 nuclear receptor elements; ERRα competes with other nuclear receptors for binding to these elements, confirmed by EMSA and ChIP.\",\n      \"method\": \"Reporter gene assays with deletion analysis, EMSA, ChIP in HepG2 cells\",\n      \"journal\": \"Chemico-biological interactions\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — EMSA + ChIP + reporter with mutagenesis, single lab\",\n      \"pmids\": [\"21513704\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"hsa-miR-495-3p and hsa-miR-486-5p post-transcriptionally suppress SULT2A1 expression by binding directly to miRNA response elements in the SULT2A1 3'-UTR and decreasing mRNA stability; this was demonstrated by RNA EMSA, luciferase reporter assays, and gain/loss-of-function experiments in HepG2 cells.\",\n      \"method\": \"Fluorescence-based RNA EMSA, luciferase reporter assays, miRNA overexpression/inhibition in HepG2 cells\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (EMSA, reporter, gain/loss-of-function), single lab\",\n      \"pmids\": [\"31445882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Hydroxylated PCB metabolites (OHPCBs) act as both substrates and inhibitors of purified recombinant SULT2A1: 4-OH PCB 34 and 4'-OH PCB 68 are substrates (with 4-OH PCB 34 showing substrate inhibition similar to DHEA), while 4'-OH PCB 9 is an inhibitor but not a substrate.\",\n      \"method\": \"In vitro enzymatic assays with purified recombinant SULT2A1\",\n      \"journal\": \"Chemical research in toxicology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — purified recombinant enzyme assays with multiple substrates/inhibitors, single lab\",\n      \"pmids\": [\"17112228\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"During the LPS-induced acute-phase response in mice, hepatic Sult2A1 mRNA and enzyme activity are suppressed in a time- and dose-dependent manner, accompanied by decreased serum DHEA-S; TNF and IL-1 mediate this suppression in human Hep3B cells, suggesting that inflammatory cytokine-driven suppression of FXR/PXR/CAR leads to decreased SULT2A1-mediated DHEA sulfation.\",\n      \"method\": \"LPS treatment in mice, RT-PCR, enzyme activity assay, serum steroid measurement, cytokine treatment of Hep3B cells\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo and in vitro convergent evidence, single lab\",\n      \"pmids\": [\"15198932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Glycyrrhetinic acid (the active component of liquorice) directly inhibits adrenal SULT2A1 activity with an IC50 of ~7 µM, decreasing sulfoconjugation of DHEA and deoxycorticosterone in adrenocortical H295 cells without altering SULT2A1 mRNA levels, increasing free DHEA and deoxycorticosterone.\",\n      \"method\": \"Adrenocortical H295 cell incubations, radiolabeled steroid conjugation assays, mRNA analysis\",\n      \"journal\": \"Molecular and cellular endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based activity assay + mRNA measurement, single lab\",\n      \"pmids\": [\"21184804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Metformin suppresses CAR-induced (but not basal) SULT2A1 expression by blocking CAR nuclear translocation via an AMPK-dependent mechanism in HepaRG cells.\",\n      \"method\": \"Western blot, cell viability assay, nuclear fractionation, HepaRG cell model with pharmacological activators/inhibitors\",\n      \"journal\": \"International journal of endocrinology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, Western blot and fractionation without orthogonal mechanistic validation\",\n      \"pmids\": [\"33643408\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Dopamine D1 receptor (DRD1) activation in HepG2 cells upregulates SULT2A1 mRNA, protein, and enzyme activity via elevated cAMP; this effect is partially blocked by DRD1 antagonist SCH23390 and reduced by DRD1-specific siRNA knockdown.\",\n      \"method\": \"RT-PCR, Western blot, HPLC enzyme activity assay, cAMP measurement, siRNA knockdown in HepG2 cells\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect pathway evidence without promoter-level mechanistic detail\",\n      \"pmids\": [\"24909515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Alpha-hydroxytamoxifen (alpha-OHTAM) stereoisomers are all substrates for human SULT2A1 (unlike rat STa where only one enantiomer is a substrate); Z-enantiomers show higher kcat/Km values with SULT2A1 than E-enantiomers, demonstrating stereospecificity in SULT2A1-catalyzed sulfation.\",\n      \"method\": \"In vitro enzymatic assays with highly purified recombinant SULT2A1, kinetic analysis of stereoisomers\",\n      \"journal\": \"Drug metabolism and disposition\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — purified recombinant enzyme with systematic stereoisomer kinetics, single lab\",\n      \"pmids\": [\"15371299\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SULT2A1 (DHEA-ST) is a cytosolic hydroxysteroid sulfotransferase that functions as a homodimer to catalyze PAPS-dependent sulfonation of DHEA, androsterone, bile acids (with highest affinity for toxic monohydroxy species such as lithocholic acid), and a range of xenobiotics including quinolone drugs and hydroxylated PCBs; substrate inhibition arises from DHEA binding at a dimerization-dependent allosteric site (governed by Tyr-238 and Met-137), and efficient DHEA sulfation requires direct protein–protein interaction between SULT2A1 and PAPSS2 (but not PAPSS1); transcription is regulated by multiple nuclear receptors (VDR, FXR, PXR, CAR, RORα/γ, LXRα, HNF4α, ERRα) and post-transcriptionally suppressed by miR-495-3p and miR-486-5p, while inflammatory cytokines (TNF, IL-1) and metformin (via AMPK-CAR axis) downregulate its expression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SULT2A1 is a cytosolic hydroxysteroid sulfotransferase that catalyzes PAPS-dependent sulfonation of steroid hormones, bile acids, and amine- and hydroxyl-containing xenobiotics, functioning as the principal enzyme for steroid and drug sulfoconjugation in liver and adrenal tissue [#0, #7, #8]. Its catalytic cycle has been resolved as an eight-form kinetic mechanism transferring the sulfuryl group from PAPS to acceptor hydroxyls and amines [#2], and crystal structures with androsterone and DHEA show that closely related substrates adopt distinct binding orientations governed by active-site residues [#0]. SULT2A1 acts as a homodimer in which each subunit carries a catalytic and an allosteric DHEA-binding site; dimerization enhances allosteric DHEA binding and produces the characteristic substrate inhibition, which is mechanistically explained by non-productive dead-end ternary complexes with the nucleotide product PAP and which depends on residues Tyr-238 (substrate release) and Met-137 (binding orientation) [#1, #3, #4]. Efficient cellular DHEA sulfation further requires a direct protein-protein interaction between SULT2A1 and PAPSS2, but not PAPSS1, channeling PAPS to the enzyme [#5]. The substrate repertoire spans DHEA, androsterone, and a graded series of bile acids whose affinity rises as hydroxylation falls—lithocholic acid being the highest-affinity acceptor [#0, #7]—as well as quinolone and other amine drugs for which SULT2A1 is the sole responsible human SULT [#8], stereoisomers of alpha-hydroxytamoxifen [#21], and hydroxylated PCB metabolites that serve as both substrates and inhibitors [#16]. SULT2A1 transcription is controlled by a network of nuclear receptors—including VDR acting with C/EBP-alpha, HNF4alpha (antagonized by PXR), ERRalpha, RORalpha/gamma, and LXRalpha [#9, #10, #11, #12, #13]—and is post-transcriptionally suppressed by miR-495-3p and miR-486-5p and downregulated by inflammatory cytokines TNF and IL-1 [#15, #17].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing that natural coding variation alters SULT2A1 function showed both protein abundance and dimerization as determinants of enzyme activity, defining a pharmacogenetic basis for inter-individual differences.\",\n      \"evidence\": \"Heterologous expression of coding SNP allozymes in COS-1 cells with Western blot, gel filtration, and activity assays\",\n      \"pmids\": [\"11990382\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phenotypic consequences in vivo not established\", \"Allele frequencies and clinical correlation outside studied population unknown\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"The first crystal structure with androsterone answered how SULT2A1 accommodates structurally similar steroids, revealing distinct substrate orientations and differing kinetics for androsterone versus DHEA.\",\n      \"evidence\": \"X-ray crystallography at 2.7 Å plus in vitro kinetics of purified recombinant enzyme\",\n      \"pmids\": [\"14573603\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of substrate inhibition not resolved from this structure alone\", \"Dimer-level allostery not captured\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Inflammatory suppression of SULT2A1 linked the enzyme to acute-phase regulation of circulating steroid sulfates, showing cytokine control over DHEA sulfation capacity.\",\n      \"evidence\": \"LPS challenge in mice plus TNF/IL-1 treatment of Hep3B cells with RT-PCR, activity, and serum steroid measurement\",\n      \"pmids\": [\"15198932\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct promoter/transcription-factor target of cytokine signaling not mapped\", \"Reliance on mouse Sult2A1 for in vivo arm\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identification of VDR/C-EBP-alpha and ERRalpha cis-elements established that SULT2A1 transcription is directed by combinatorial nuclear-receptor inputs in hepatic and adrenal contexts.\",\n      \"evidence\": \"Reporter assays, EMSA, DNase footprinting, ChIP, and Co-IP for VDR/C-EBP-alpha; reporter and EMSA for ERRalpha\",\n      \"pmids\": [\"16357103\", \"15878968\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of each receptor in physiological tissue not quantified\", \"Endogenous coactivator stoichiometry undefined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defining HNF4alpha as a central activator antagonized by PXR clarified how xenobiotic-sensing signaling reshapes hepatic SULT2A1 expression.\",\n      \"evidence\": \"Reporter assays, in vitro binding, mutagenesis, ChIP, and siRNA in HepG2 cells and primary human hepatocytes\",\n      \"pmids\": [\"17687072\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which PXR interferes with HNF4alpha activity not fully defined\", \"Interplay with other identified receptors not integrated\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrating SULT2A1 as the unique human SULT for quinolone N-sulfoconjugation extended its role from steroid metabolism to drug detoxification.\",\n      \"evidence\": \"Recombinant SULT panel and human liver cytosol kinetic correlation\",\n      \"pmids\": [\"19420132\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo pharmacokinetic relevance not established\", \"Toxicological consequences of N-sulfo metabolites unaddressed\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Multiple studies resolved the homodimeric, allosterically inhibited architecture: a monomeric fusion lacks substrate inhibition, two DHEA sites exist per subunit, and inhibition arises from PAP-containing dead-end complexes, explaining the enzyme's nonlinear kinetics.\",\n      \"evidence\": \"Size-exclusion chromatography, intrinsic fluorescence, and initial-velocity/equilibrium binding studies with purified recombinant enzyme\",\n      \"pmids\": [\"21822453\", \"25961208\", \"21187059\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological significance of substrate inhibition in vivo unclear\", \"Structural snapshot of the allosteric DHEA-bound dimer not solved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Systematic bile-acid kinetics established that sulfation affinity scales inversely with hydroxyl number, positioning SULT2A1 to preferentially detoxify the most hydrophobic, toxic monohydroxy bile acids.\",\n      \"evidence\": \"Stable HEK293 expression with kinetic enzymatic assays across 15 bile acids\",\n      \"pmids\": [\"20102295\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo contribution to bile-acid homeostasis not measured\", \"Competition with steroid substrates not assessed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that ERRalpha can also repress the SULT2A1 promoter by competing at overlapping nuclear-receptor elements revealed context-dependent, bidirectional control of the gene.\",\n      \"evidence\": \"Reporter deletion assays, EMSA, and ChIP in HepG2 cells\",\n      \"pmids\": [\"21513704\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation of activating versus repressing ERRalpha roles across tissues unresolved\", \"Competing factors at the overlapping elements not all identified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"RORalpha/gamma and LXRalpha were added as activators acting through promoter elements, broadening the lipid/sterol-sensing receptor network governing SULT2A1.\",\n      \"evidence\": \"Reporter assays, EMSA, ChIP, and siRNA in HepG2 cells and primary human hepatocytes (RORalpha/gamma 2012; LXRalpha 2014)\",\n      \"pmids\": [\"23211525\", \"25028566\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Hierarchy among the overlapping ROR/CAR and other receptor elements not resolved\", \"Ligand-dependence in vivo not established\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Mutagenesis pinpointed Tyr-238 and Met-137 as the residues governing substrate inhibition, assigning specific structural determinants to substrate release and binding orientation.\",\n      \"evidence\": \"Site-directed mutagenesis, kinetic assays, and crystal structures of Met-137 mutants\",\n      \"pmids\": [\"18042734\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Link between these residues and the dimer-dependent allosteric site not structurally co-resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"A complete eight-form, 22-rate-constant kinetic mechanism provided a quantitative description of sulfuryl transfer, anchoring all prior phenomenological kinetics in a unified scheme.\",\n      \"evidence\": \"Comprehensive in vitro kinetic analysis with independently determined rate constants\",\n      \"pmids\": [\"25056952\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism derived in vitro; cellular PAPS channeling not incorporated\", \"Allosteric inhibition not embedded in the scheme\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identifying a direct SULT2A1-PAPSS2 interaction explained selective sulfodonor channeling, connecting cofactor supply physically to the sulfotransferase.\",\n      \"evidence\": \"Proximity ligation assay, siRNA knockdown in NCI-H295R1 cells, and molecular docking\",\n      \"pmids\": [\"29743239\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction not confirmed by reciprocal structural or co-purification methods\", \"Docked binding site not experimentally validated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of miR-495-3p and miR-486-5p added a post-transcriptional layer of SULT2A1 control through 3'-UTR binding and mRNA destabilization.\",\n      \"evidence\": \"RNA EMSA, luciferase reporter, and miRNA gain/loss-of-function in HepG2 cells\",\n      \"pmids\": [\"31445882\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo regulatory relevance not shown\", \"Upstream signals controlling these miRNAs unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Pharmacological inputs (metformin via AMPK-CAR, dopamine D1 receptor via cAMP) were shown to modulate SULT2A1, extending its regulation to drug- and signaling-driven contexts.\",\n      \"evidence\": \"HepaRG metformin study with nuclear fractionation; HepG2 DRD1 study with RT-PCR, Western blot, cAMP, and siRNA (2014)\",\n      \"pmids\": [\"33643408\", \"24909515\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single-lab studies without orthogonal mechanistic validation\", \"Promoter-level targets of these signals not mapped\", \"In vivo relevance unestablished\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the in vitro allosteric/substrate-inhibition mechanism and the PAPSS2-channeled, nuclear-receptor- and miRNA-regulated cellular state integrate to set tissue-specific steroid and bile-acid sulfation flux in vivo remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the allosteric DHEA-bound dimer\", \"PAPSS2 interaction lacks structural confirmation\", \"Physiological consequence of substrate inhibition unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 2, 7, 8]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [7, 18]},\n      {\"term_id\": \"R-HSA-9748784\", \"supporting_discovery_ids\": [8, 21]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [9, 10, 12, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"PAPSS2\",\n      \"HNF4A\",\n      \"VDR\",\n      \"CEBPA\",\n      \"ESRRA\",\n      \"RORA\",\n      \"RORC\",\n      \"NR1H3\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}