CYP19A1 (aromatase; cytochrome P450 19A1; P-450AROM; estrogen synthase; EC 1.14.14.14) is a microsomal, endoplasmic-reticulum-membrane heme-thiolate cytochrome P450 monooxygenase that catalyzes the rate-limiting, committed step of estrogen biosynthesis: the aromatization of C19 androgens to C18 estrogens. In three sequential oxidations, each consuming one molecule of O2 and one of NADPH supplied via cytochrome P450 reductase (POR), it removes the C19 angular methyl group and aromatizes the steroid A-ring, converting androst-4-ene-3,17-dione (androstenedione) to estrone and testosterone to 17beta-estradiol; the first two steps are C19-methyl hydroxylations (19-hydroxy then 19-oxo/aldehyde) and the third, unique step is A-ring aromatization with C1-beta hydrogen abstraction, C10-C19 bond cleavage, and release of formic acid. The heme iron is axially coordinated by a conserved cysteine thiolate, and membrane anchoring via the hydrophobic N-terminal segment is required to give lipophilic steroid substrates access to the active site. Aromatase is the only vertebrate enzyme that makes estrogens from androgens. It is expressed via tissue-specific alternative promoters in the gonads (ovarian granulosa cells, testis), placenta, adipose tissue, brain, skin fibroblasts, and bone. Loss of function causes aromatase deficiency (virilization, tall stature from unfused epiphyses, and osteoporosis), whereas gain/overexpression causes aromatase excess syndrome (gynecomastia and precocity); aromatase is the pharmacological target of aromatase-inhibitor therapy (letrozole, anastrozole, exemestane) for estrogen-dependent breast cancer. Minor secondary activities include 2-hydroxylation of estrone and oxidation of dihydrotestosterone to 19-nor products.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: Aromatase is a microsomal cytochrome P450 that resides in the endoplasmic reticulum, so the ER localization is correct. This is a phylogenetic (IBA) annotation consistent with the more precise experimental ER-membrane annotations. Reason: Correct compartment; the endoplasmic reticulum membrane (GO:0005789) is the more precise location and is the core CC annotation, but the ER parent term is also accurate. Supporting Evidence: PMID:19129847 structure of this enzyme of the endoplasmic reticulum membrane file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane |
| GO:0008585 female gonad development | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Estrogen produced by ovarian aromatase is required for normal ovarian follicle development and female reproductive function; aromatase deficiency causes multicystic ovaries and delayed puberty. This IBA developmental annotation is biologically supported but reflects a downstream physiological consequence of estrogen synthesis rather than the enzyme's core molecular role. Reason: Accurate but non-core: it captures the developmental/physiological outcome of estrogen biosynthesis in the ovary rather than aromatase's catalytic function; retained as non-core. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt aromatase deficiency |
| GO:0032355 response to estradiol | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: Aromatase synthesizes 17beta-estradiol; it is the enzyme that produces estradiol rather than a protein whose activity is a cellular response to estradiol. This IBA "response to estradiol" term appears to be an over-propagation from the phylogenetic family and does not describe aromatase's own function. Reason: "Response to estradiol" mischaracterizes the direction of the relationship: CYP19A1 is the biosynthetic source of estradiol, not a downstream responder. Over-annotated via IBA propagation across the aromatase/P450 group. Propagation Review Root cause: TERM SCOPING PROBLEM Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0070330 aromatase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Aromatase activity is the defining, phylogenetically conserved molecular function of CYP19A1 and is the single most informative core MF term. This IBA is strongly corroborated by multiple experimental (EXP/IDA) annotations. Reason: Core molecular function of the gene product, conserved across the aromatase clade and directly demonstrated experimentally in human enzyme. Supporting Evidence: PMID:2848247 catalyzed the aromatization of androstenedione, testosterone, and 16 alpha-hydroxyandrostenedione file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0004497 monooxygenase activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Monooxygenase activity is a correct but very general parent of the specific aromatase activity (GO:0070330) that CYP19A1 enables; aromatase is a cytochrome P450 monooxygenase. Reason: InterPro-derived general term that is an ancestor of the specific, experimentally supported MF GO:0070330; over-general for the core function. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0005506 iron ion binding | IEA GO_REF:0000002 | ACCEPT | Summary: As a heme-thiolate cytochrome P450, aromatase binds a heme prosthetic group whose iron is catalytically essential (axially coordinated by Cys437). Iron ion binding is a correct cofactor-level MF, supporting but secondary to aromatase activity. Reason: Correct cofactor function (heme iron) demonstrated in the crystal structure; secondary to the core catalytic MF. Supporting Evidence: PMID:19129847 consists of a haem group and a polypeptide chain of 503 amino-acid residues file:human/CYP19A1/CYP19A1-uniprot.txt Name=heme; Xref=ChEBI:CHEBI:30413 |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Aromatase is a multi-pass endoplasmic reticulum membrane (microsomal) protein; the UniProt SubCell mapping to ER membrane is correct and matches the experimental localization. Reason: Correct core cellular component, consistent with the experimental (EXP/TAS) ER-membrane annotations. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane file:human/CYP19A1/CYP19A1-uniprot.txt Multi-pass membrane protein |
| GO:0006703 estrogen biosynthetic process | IEA GO_REF:0000117 | ACCEPT | Summary: Estrogen biosynthetic process is the core biological process for aromatase, which performs the committed, rate-limiting step converting androgens to estrogens. This ARBA electronic annotation is correct and matches the Reactome TAS annotation of the same term. Reason: Core BP: aromatase is the terminal, committed enzyme of estrogen biosynthesis. Supporting Evidence: PMID:19129847 the only enzyme in vertebrates known to catalyse the biosynthesis of all oestrogens from androgens file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0008209 androgen metabolic process | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: Aromatase consumes C19 androgens (androstenedione, testosterone) as substrates, so it participates in androgen metabolism. This is accurate but describes the substrate side of the reaction; the productive biological role is estrogen biosynthesis. Reason: Substrate-level metabolic term; accurate but secondary to the estrogen biosynthetic process that represents the enzyme's core role. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0016705 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: This is a broad oxidoreductase parent describing the general P450 monooxygenase chemistry (incorporation/reduction of O2). It is a correct ancestor of the specific aromatase activity but is over-general for the core function. Reason: General InterPro-derived class; an ancestor of GO:0070330 (aromatase activity) that is already annotated experimentally. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0016712 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen | IEA GO_REF:0000117 | MARK AS OVER ANNOTATED | Summary: This term describes the EC 1.14.14.- class of monooxygenases using a reduced flavoprotein (cytochrome P450 reductase) as the electron donor, which correctly matches the aromatase reaction mechanism. However it is a general parent of the specific aromatase activity. Reason: Correct EC-level parent (P450 monooxygenase using flavoprotein/POR as donor) but over-general; the specific MF GO:0070330 is annotated with experimental evidence. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0020037 heme binding | IEA GO_REF:0000002 | ACCEPT | Summary: Aromatase is a heme-thiolate cytochrome P450; heme binding is a correct, structurally confirmed cofactor MF supporting catalysis. Secondary to the core aromatase activity. Reason: Correct cofactor binding demonstrated in the crystal structure (heme with axial Cys437); supporting/secondary function. Supporting Evidence: PMID:19129847 consists of a haem group and a polypeptide chain of 503 amino-acid residues file:human/CYP19A1/CYP19A1-uniprot.txt Name=heme; Xref=ChEBI:CHEBI:30413 |
| GO:0070330 aromatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Automated (UniProt RHEA/EC 1.14.14.14) assignment of the correct core molecular function, aromatase activity, consistent with the experimental annotations. Reason: Correct core MF from EC/RHEA mapping; redundant with experimental copies but valid. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0101021 estrogen 2-hydroxylase activity | IEA GO_REF:0000116 | KEEP AS NON CORE | Summary: Aromatase displays a minor 2-hydroxylase activity toward estrone (producing 2-hydroxyestrone), demonstrated biochemically. This RHEA-mapped MF is a genuine but secondary/minor activity, not the core function. Reason: Real secondary catalytic activity (estrone 2-hydroxylation) but minor relative to the core androgen-aromatization function. Supporting Evidence: PMID:22773874 the 2-hydrogen from estrone file:human/CYP19A1/CYP19A1-uniprot.txt Also displays 2-hydroxylase activity |
| GO:0001541 ovarian follicle development | IDA PMID:30541132 Oocyte-Secreted Factors Synergize With FSH to Promote Aromat... | KEEP AS NON CORE | Summary: In primary human cumulus granulosa cells, FSH together with oocyte-secreted factors (GDF9/ BMP15) induces CYP19A1 expression and estradiol production, linking aromatase to follicle development and maturation. This is a physiological/developmental role driven by estrogen synthesis rather than the core molecular function. Reason: Experimentally supported physiological role in the ovarian follicle; retained as non-core because it reflects the downstream developmental consequence of aromatase-driven estrogen production. Supporting Evidence: PMID:30541132 These effects translate into an increase in estradiol production PMID:30541132 the oocyte have the capacity to regulate the expression of aromatase |
| GO:0006703 estrogen biosynthetic process | TAS Reactome:R-HSA-193144 | ACCEPT | Summary: Reactome traceable annotation to estrogen biosynthesis, the core biological process of aromatase (committed, rate-limiting step converting androgens to estrogens). Reason: Core BP, consistent with the ARBA IEA annotation of the same term and with the enzyme's catalytic role. Supporting Evidence: PMID:19129847 the only enzyme in vertebrates known to catalyse the biosynthesis of all oestrogens from androgens |
| GO:0016125 sterol metabolic process | TAS Reactome:R-HSA-211976 | MARK AS OVER ANNOTATED | Summary: Aromatase acts on C19 androgens and produces C18 estrogens, which are steroid hormones, not sterols; aromatase does not metabolize sterols (e.g. cholesterol). Sterol metabolic process is an over-broad/imprecise grouping for this enzyme. Reason: Estrogens and their androgen substrates are steroids but not sterols; the reaction belongs to steroid/estrogen biosynthesis, so this sterol-metabolism grouping is an over-annotation. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0005789 endoplasmic reticulum membrane | EXP PMID:2973313 Cloning of a complete cDNA encoding human aromatase: immunoc... | ACCEPT | Summary: The original cloning and immunochemical characterization of human placental aromatase established it as a microsomal (ER-membrane) cytochrome P450. Experimental support for the core cellular location. Reason: Experimentally supported core cellular component (ER/microsome membrane). Supporting Evidence: PMID:19129847 structure of this enzyme of the endoplasmic reticulum membrane file:human/CYP19A1/CYP19A1-uniprot.txt Microsome membrane |
| GO:0070330 aromatase activity | EXP PMID:27702664 Impact of R264C and R264H polymorphisms in human aromatase f... | ACCEPT | Summary: Recombinant human aromatase and its R264C/R264H variants were characterized by steady-state kinetics of androgen-to-estrogen conversion, directly demonstrating aromatase activity. Reason: Direct experimental support for the core molecular function. Supporting Evidence: PMID:27702664 The cytochrome P450 aromatase is involved in the last step of sex hormones biosynthesis by converting androgens into estrogens |
| GO:0070330 aromatase activity | EXP PMID:2848247 Isolation of a full-length cDNA insert encoding human aromat... | ACCEPT | Summary: The full-length human aromatase cDNA expressed in nonsteroidogenic COS-1 cells catalyzed the aromatization of androstenedione, testosterone, and 16-alpha-hydroxyandrostenedione, and was inhibited by known aromatase inhibitors, directly demonstrating aromatase activity. Reason: Direct experimental support for the core molecular function; establishes that a single polypeptide catalyzes the multi-step aromatization. Supporting Evidence: PMID:2848247 catalyzed the aromatization of androstenedione, testosterone, and 16 alpha-hydroxyandrostenedione PMID:2848247 the several steps involved in the aromatization reaction appear to be catalyzed by a single polypeptide chain |
| GO:0101021 estrogen 2-hydroxylase activity | EXP PMID:22773874 Oxidation of dihydrotestosterone by human cytochromes P450 1... | KEEP AS NON CORE | Summary: Guengerich and colleagues showed experimentally that P450 19A1 removes the 2-hydrogen from estrone (2-hydroxylation), a genuine but minor secondary activity distinct from the core androgen-aromatization function. Reason: Experimentally demonstrated but minor/secondary catalytic activity toward estrone. Supporting Evidence: PMID:22773874 the 2-hydrogen from estrone |
| GO:0008395 steroid hydroxylase activity | TAS Reactome:R-HSA-193060 | MARK AS OVER ANNOTATED | Summary: Steroid hydroxylase activity is a correct general parent describing the first two (C19 hydroxylation) steps of the aromatase reaction, but it is over-general relative to the specific aromatase activity (GO:0070330). Reason: General MF parent of the specific, experimentally supported aromatase activity; over-general for the core function. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Catalyzes three successive |
| GO:0008395 steroid hydroxylase activity | TAS Reactome:R-HSA-193143 | MARK AS OVER ANNOTATED | Summary: Duplicate Reactome annotation of the general steroid hydroxylase parent (for the testosterone -> estradiol reaction); over-general relative to aromatase activity. Reason: General MF parent; the specific aromatase activity (GO:0070330) is the informative core term. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Catalyzes three successive |
| GO:0008395 steroid hydroxylase activity | TAS Reactome:R-HSA-5601849 | MARK AS OVER ANNOTATED | Summary: Duplicate Reactome annotation of the general steroid hydroxylase parent (defective-aromatase pathway); over-general relative to the specific aromatase activity. Reason: General MF parent; superseded for the core function by the specific GO:0070330. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Catalyzes three successive |
| GO:0006710 androgen catabolic process | IDA PMID:26482249 Osteopontin promotes aromatase expression and estradiol prod... | KEEP AS NON CORE | Summary: In human adipocytes, osteopontin induces aromatase, which consumes testosterone to produce estradiol; from the substrate perspective the androgen is catabolized. This is accurate as the substrate side of aromatization but is secondary to the productive estrogen-biosynthesis role. Reason: Reflects consumption/catabolism of androgen substrate; accurate but non-core relative to estrogen biosynthesis. Supporting Evidence: PMID:26482249 cOPN more effectively than full-length OPN upregulated aromatase mRNA in adipocytes and significantly increased aromatase protein level and estradiol production |
| GO:0070330 aromatase activity | IDA PMID:26482249 Osteopontin promotes aromatase expression and estradiol prod... | ACCEPT | Summary: Human adipocytes with induced aromatase converted supplied testosterone to estradiol, directly demonstrating aromatase activity in a physiological cell context. Reason: Direct experimental support for the core molecular function in human adipocytes. Supporting Evidence: PMID:26482249 the estrogen-synthesizing enzyme aromatase PMID:26482249 cOPN more effectively than full-length OPN upregulated aromatase mRNA in adipocytes and significantly increased aromatase protein level and estradiol production |
| GO:2000866 positive regulation of estradiol secretion | IDA PMID:26482249 Osteopontin promotes aromatase expression and estradiol prod... | KEEP AS NON CORE | Summary: Osteopontin-induced aromatase increased estradiol production/secretion by human adipocytes. Aromatase enables estradiol output, so its induction positively influences estradiol secretion; this is a downstream physiological effect rather than the enzyme's molecular function. Reason: Physiological/regulatory outcome of aromatase activity; accurate but non-core. Supporting Evidence: PMID:26482249 cOPN more effectively than full-length OPN upregulated aromatase mRNA in adipocytes and significantly increased aromatase protein level and estradiol production |
| GO:0005789 endoplasmic reticulum membrane | TAS Reactome:R-HSA-5601849 | ACCEPT | Summary: Reactome traceable annotation to the ER membrane, the core cellular location of the microsomal aromatase. Reason: Correct core cellular component; consistent with experimental ER-membrane localization. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | TAS Reactome:R-HSA-193060 | ACCEPT | Summary: Duplicate Reactome annotation to the ER membrane (androstenedione -> estrone reaction context); correct core location. Reason: Correct core cellular component. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | TAS Reactome:R-HSA-193143 | ACCEPT | Summary: Duplicate Reactome annotation to the ER membrane (testosterone -> estradiol reaction context); correct core location. Reason: Correct core cellular component. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | TAS Reactome:R-HSA-9707353 | ACCEPT | Summary: Duplicate Reactome annotation to the ER membrane (aromatase-inhibitor binding context); correct core location. Reason: Correct core cellular component. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane |
| GO:0005783 endoplasmic reticulum | IDA GO_REF:0000054 | ACCEPT | Summary: LIFEdb fluorescent-fusion localization to the endoplasmic reticulum, consistent with the established microsomal ER-membrane localization of aromatase. Reason: Correct compartment; ER membrane (GO:0005789) is the more precise core location. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Endoplasmic reticulum membrane |
| GO:0020037 heme binding | IDA PMID:19129847 Structural basis for androgen specificity and oestrogen synt... | ACCEPT | Summary: The crystal structure of human placental aromatase directly demonstrates a bound heme group (iron coordinated by Cys437), confirming heme binding as an essential cofactor function. Reason: Direct structural evidence for heme binding; supporting/secondary to the core catalytic MF. Supporting Evidence: PMID:19129847 The residues in aromatase involved in haem coordination are Arg 115 PMID:19129847 consists of a haem group and a polypeptide chain of 503 amino-acid residues |
| GO:0070330 aromatase activity | IDA PMID:19129847 Structural basis for androgen specificity and oestrogen synt... | ACCEPT | Summary: Aromatase purified from term human placenta was highly active toward androstenedione and its structure captured with the natural substrate, supporting aromatase activity (the enzyme catalyzing androgen-to-estrogen conversion). Reason: Experimental/structural support for the core molecular function. Supporting Evidence: PMID:19129847 aromatase converts androstenedione, testosterone and 16alpha-hydroxytestosterone to oestrone |
| GO:0016712 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen, reduced flavin or flavoprotein as one donor, and incorporation of one atom of oxygen | TAS PMID:1371509 Biochemical and molecular genetic analyses on placental arom... | MARK AS OVER ANNOTATED | Summary: General EC 1.14.14.- oxidoreductase parent describing P450-monooxygenase chemistry using a flavoprotein electron donor (POR). Correct at the class level but over-general relative to the specific aromatase activity. Reason: Over-general EC-class parent of GO:0070330; the specific MF is the informative core term. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt A cytochrome P450 monooxygenase that catalyzes the conversion |
| GO:0009055 electron transfer activity | TAS PMID:2848247 Isolation of a full-length cDNA insert encoding human aromat... | REMOVE | Summary: Electron transfer activity (GO:0009055) is the function of electron-carrier/shuttle proteins. Aromatase is the terminal cytochrome P450 oxygenase: it RECEIVES two electrons from NADPH via cytochrome P450 reductase (POR) to activate O2, but it is not itself an electron carrier. The P450 monooxygenase reaction is captured by aromatase/monooxygenase MF terms, and the cited 1988 cloning paper does not establish an electron-transfer-carrier function for the enzyme. Reason: Mischaracterizes aromatase as an electron carrier; it is a heme-thiolate monooxygenase that accepts electrons from POR rather than transferring electrons as a shuttle. Demonstrably wrong MF for a terminal P450 oxygenase. Supporting Evidence: PMID:19129847 coupling with its redox partner cytochrome P450 reductase PMID:1371509 Of the enzymes participating in the electron transport system of placental microsomes |
| GO:0019825 oxygen binding | TAS PMID:2848247 Isolation of a full-length cDNA insert encoding human aromat... | MARK AS OVER ANNOTATED | Summary: Molecular oxygen is a co-substrate activated at the heme iron during each aromatase oxidation step. However, oxygen binding (GO:0019825) is typically reserved for O2-carrier/storage proteins (e.g. hemoglobin); for a monooxygenase, O2 activation is subsumed by the monooxygenase/aromatase MF terms, making this an over-annotation. Reason: O2 is a reaction co-substrate rather than a carried ligand; the catalytic use of O2 is captured by the monooxygenase/aromatase MF terms. Supporting Evidence: PMID:19129847 each step requiring 1 mol of O(2), 1 mol of NADPH, and coupling with its redox partner cytochrome P450 reductase |
| GO:0006694 steroid biosynthetic process | TAS PMID:2848247 Isolation of a full-length cDNA insert encoding human aromat... | KEEP AS NON CORE | Summary: Steroid biosynthetic process is a correct but general parent of the specific estrogen biosynthetic process (GO:0006703) that aromatase performs; estrogens are steroid hormones. Reason: Accurate general BP; the specific estrogen biosynthetic process is the informative core BP. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Steroid hormone biosynthesis |
| GO:0016020 membrane | TAS PMID:2848247 Isolation of a full-length cDNA insert encoding human aromat... | MARK AS OVER ANNOTATED | Summary: Aromatase is a membrane protein, but "membrane" is an over-general cellular component; the specific and correct location is the endoplasmic reticulum (microsome) membrane (GO:0005789). Reason: Over-general CC; superseded by the specific ER-membrane annotations. Supporting Evidence: file:human/CYP19A1/CYP19A1-uniprot.txt Multi-pass membrane protein |
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Download this section (compressed HTML)Q: Beyond the well-characterized estrogen-biosynthetic role, do the minor activities (estrone 2-hydroxylation; dihydrotestosterone oxidation to 19-nor products) have a demonstrable in vivo physiological function, e.g. in local androgen homeostasis?
Q: How does PKA/PKG phosphorylation of aromatase modulate its activity in vivo across the different tissue-specific expression contexts (placenta, adipose, brain, gonad)?
Experiment: Tissue-specific conditional knockout / promoter-specific expression studies to quantify the contribution of each alternative promoter (placental, adipose, brain, gonadal) to circulating versus local estrogen pools.
Experiment: Reconstituted-membrane kinetic assays with defined POR (and cytochrome b5) stoichiometry to dissect how redox-partner availability governs the three sequential oxidation steps and the minor 2-hydroxylase activity.
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