GO:0047751 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047751 defines the NADP+-dependent enzyme activity that converts a 3-oxo-5alpha-steroid into a 3-oxo-delta(4)-steroid, producing NADPH and H+.
• This activity is classically known as steroid 5alpha-reductase and is essential for converting testosterone to the more potent androgen dihydrotestosterone.
• The reaction is a net 5alpha-hydrogenation coupled to NADP+ reduction, and enzyme activity can be modulated by phosphorylation state.
• Membrane phospholipid environment regulates epididymal delta 4-steroid 5alpha-reductase activity in vitro.
• Inhibitors of this activity are used to treat benign prostatic hyperplasia and are studied in prostate cancer active surveillance.
• The activity is conserved from bacteria to mammals, with a characterized bacterial 3-ketosteroid-delta 4(5alpha)-dehydrogenase.
Description
GO:0047751, 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity, is a molecular function that catalyzes the NADP+-dependent oxidation of a 3-oxo-5alpha-steroid to a 3-oxo-delta(4)-steroid, yielding NADPH and H+. This activity is widely known as steroid 5alpha-reductase and is central to androgen metabolism because it converts testosterone into the more potent androgen dihydrotestosterone. Researchers study this activity to understand androgen-driven physiology and to develop inhibitors for prostate disease. The enzyme has been characterized in rat liver, where its activity is modulated by changes in phosphorylation state, and in rat epididymis, where phospholipid environment influences activity. A bacterial counterpart, Comamonas testosteroni 3-ketosteroid-delta 4(5alpha)-dehydrogenase, has also been cloned and characterized, showing the evolutionary conservation of this catalytic activity. Because the reaction controls the balance between precursor and 5alpha-reduced steroids, it is a key node in endocrine, reproductive, and cancer biology.
3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity At A Glance
| GO ID | GO:0047751 |
|---|---|
| GO term | 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity |
| Ontology | molecular_function |
| Synonym | 3-oxosteroid 5alpha-reductase activity; 3-oxosteroid delta4-dehydrogenase; cholestenone 5-alpha-reductase activity; cholestenone 5alpha-reductase activity; cholestenone 5a-reductase activity; progesterone 5-alpha-reductase activity; steroid 5alpha-hydrogenase activity; steroid 5alpha-reductase; sterol 5-alpha reductase activity; testosterone 5alpha-reductase; testosterone delta4-hydrogenase activity |
| Major function | NADP+-dependent conversion of a 3-oxo-5alpha-steroid to a 3-oxo-delta(4)-steroid, producing NADPH and H+ |
| Reaction | 3-oxo-5alpha-steroid + NADP+ = a 3-oxo-delta(4)-steroid + H+ + NADPH |
| Cofactor | NADP+ (nicotinamide adenine dinucleotide phosphate, oxidized) |
| Substrate class | 3-oxo-5alpha-steroids, including testosterone and progesterone derivatives |
| Product class | 3-oxo-delta(4)-steroids, including dihydrotestosterone from testosterone |
What Is GO:0047751?
In my own words, GO:0047751 describes an enzyme activity that removes two hydrogen atoms from a 3-oxo-5alpha-steroid substrate in an NADP+-dependent manner, forming a 3-oxo-delta(4)-steroid product while reducing NADP+ to NADPH and releasing a proton. The official QuickGO definition is: Catalysis of the reaction: 3-oxo-5alpha-steroid + NADP+ = a 3-oxo-delta(4)-steroid + H+ + NADPH. This activity is synonymous with steroid 5alpha-reductase, 3-oxosteroid 5alpha-reductase, and testosterone 5alpha-reductase, among other names.
Why Is 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity Important in Cell Biology?
GO:0047751 is important because it governs the production of 5alpha-reduced steroids, most notably dihydrotestosterone, which amplifies androgen signaling in tissues such as prostate and skin. Pharmacological inhibition of this activity is a mainstay for benign prostatic hyperplasia and is being explored in prostate cancer active surveillance. The activity is also a model for understanding how post-translational modifications and membrane lipids control steroidogenic enzymes, as shown by phosphorylation-dependent modulation in rat liver and phospholipid-dependent modulation in rat epididymis. Comparative studies of bacterial and mammalian enzymes reveal conserved catalytic features that inform inhibitor design.
• Controls conversion of testosterone to the more potent androgen dihydrotestosterone, a driver of prostate growth.
• Provides the molecular target for 5alpha-reductase inhibitors used in benign prostatic hyperplasia.
• Is being evaluated as a target in prostate cancer active surveillance, with NKX3.1 expression as an adjunct marker.
• Shows activity modulation by phosphorylation state, linking signaling to steroid metabolism.
• Is regulated by membrane phospholipid environment in epididymal tissue.
• Has a characterized bacterial homolog, enabling comparative enzymology and inhibitor studies.
• Is a focus of 3D-QSAR studies for designing steroidal 5alpha-reductase inhibitors.
• Plays a role in epididymal development and function, as shown by developmental changes in rat epididymis.
• Represents a conserved NADP+-dependent dehydrogenase mechanism across species.
• Offers a tractable enzyme activity for biochemical assays and drug screening.
Molecular Mechanism of 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity
Substrate recognition and binding
In simple terms: The enzyme grabs a steroid molecule that already has a 3-oxo group and a 5alpha-hydrogen.
The activity acts on 3-oxo-5alpha-steroids, a class that includes testosterone and progesterone derivatives. Substrate specificity has been studied through comparative 3D-QSAR analysis of steroidal 5alpha-reductase inhibitors, which highlights the structural features required for binding. In rat epididymis, the enzyme activity changes during development, suggesting developmental regulation of substrate access or enzyme abundance.
Catalytic hydrogen transfer and NADP+ reduction
In simple terms: The enzyme removes hydrogens from the steroid and transfers them to NADP+, making NADPH.
The reaction catalyzed is: 3-oxo-5alpha-steroid + NADP+ = a 3-oxo-delta(4)-steroid + H+ + NADPH. This is a net dehydrogenation that introduces a double bond between carbons 4 and 5 of the steroid A-ring while reducing NADP+. The bacterial enzyme Comamonas testosteroni 3-ketosteroid-delta 4(5alpha)-dehydrogenase catalyzes an analogous reaction, and its gene and protein have been characterized.
Cofactor requirement and redox balance
In simple terms: The enzyme needs NADP+ as a cofactor to accept electrons.
NADP+ is the specific electron acceptor for this activity, distinguishing it from NAD+-dependent dehydrogenases. The reaction produces NADPH, which can feed into reductive biosynthesis or redox signaling. The phosphorylation state of rat liver 3-oxo-5alpha-steroid delta 4-dehydrogenase modulates its activity, indicating that cellular redox and signaling states can influence flux through this step.
Membrane environment and regulation
In simple terms: The enzyme sits in membranes, and the lipids around it can change how well it works.
Epididymal delta 4-steroid 5alpha-reductase activity is modulated in vitro by the phospholipid environment, showing that membrane composition affects catalysis. This suggests that the enzyme is membrane-associated and that lipid-protein interactions are part of its regulation. Developmental studies in rat epididymis show that activity changes with age, consistent with tissue-specific and developmental control.
Inhibitor binding and pharmacological blockade
In simple terms: Drugs can block this enzyme, lowering dihydrotestosterone production.
Steroidal 5alpha-reductase inhibitors have been reviewed and compared using 3D-QSAR, providing a framework for understanding how inhibitors occupy the active site. Inhibition of this activity is used to treat benign prostatic hyperplasia and is being investigated in prostate cancer active surveillance. The bacterial enzyme provides a comparative model for inhibitor binding studies.
Key Genes Involved in GO:0047751 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity
The genes and proteins below are directly or functionally linked to GO:0047751, 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity, based on the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SRD5A1 | Steroid 5alpha-reductase type 1, catalyzes 3-oxo-5alpha-steroid 4-dehydrogenase activity | Target for inhibitor studies and androgen metabolism research |
| SRD5A2 | Steroid 5alpha-reductase type 2, catalyzes 3-oxo-5alpha-steroid 4-dehydrogenase activity | Key target in benign prostatic hyperplasia and prostate cancer |
| SRD5A3 | Steroid 5alpha-reductase type 3, related 5alpha-reductase family member | Studied in steroid metabolism and inhibitor design |
| NKX3.1 | Prostate-specific tumor suppressor used as an adjunct marker | Supports 5alpha-reductase inhibition intervention in active surveillance |
| AR | Androgen receptor, mediates dihydrotestosterone signaling | Downstream effector of 5alpha-reductase activity |
| CYP17A1 | Steroidogenic enzyme upstream of androgen synthesis | Context for substrate supply to 5alpha-reductase |
| HSD3B2 | 3beta-hydroxysteroid dehydrogenase, upstream steroidogenesis | Provides 3-oxo-steroid precursors |
| CYP19A1 | Aromatase, balances androgen to estrogen conversion | Indirectly affects 5alpha-reduced steroid levels |
| Comamonas testosteroni 3-ketosteroid-delta 4(5alpha)-dehydrogenase | Bacterial homolog of 3-oxo-5alpha-steroid 4-dehydrogenase | Model for enzyme mechanism and inhibitor binding |
| Rat liver 3-oxo-5alpha-steroid delta 4-dehydrogenase | Phosphorylation-modulated enzyme activity | Model for post-translational regulation |
| Rat epididymal delta 4-steroid 5alpha-reductase | Phospholipid-modulated enzyme activity | Model for membrane regulation |
| Rat epididymal 3alpha-hydroxysteroid dehydrogenase | Related steroid oxidoreductase | Studied alongside 5alpha-reductase during development |
| Progesterone 5-alpha-reductase | Synonym activity acting on progesterone derivatives | Substrate diversity of GO:0047751 |
| Cholestenone 5-alpha-reductase | Synonym activity acting on cholestenone | Substrate diversity of GO:0047751 |
| Testosterone 5alpha-reductase | Synonym activity converting testosterone to dihydrotestosterone | Central to androgen physiology |
| Sterol 5-alpha reductase | Synonym activity in sterol metabolism | Broader sterol processing context |
| 3-oxosteroid delta4-dehydrogenase | Synonym activity | Historical nomenclature for GO:0047751 |
| Steroid 5alpha-hydrogenase | Synonym activity | Historical nomenclature for GO:0047751 |
How Is 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity Regulated?
The activity of 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) is regulated at multiple levels. In rat liver, changes in phosphorylation state modulate enzyme activity, indicating post-translational control. In rat epididymis, the phospholipid environment modulates delta 4-steroid 5alpha-reductase activity in vitro, showing membrane-level regulation. Developmental studies in rat epididymis reveal that activity changes during development, suggesting hormonal or developmental regulation. Pharmacological regulation is achieved by steroidal 5alpha-reductase inhibitors, which block the enzyme and reduce dihydrotestosterone production. In prostate cancer active surveillance, NKX3.1 expression has been proposed as an adjunct marker to support 5alpha-reductase inhibition intervention.
3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SRD5A2 | Benign prostatic hyperplasia | Knockout or point-mutation prostate cell lines |
| SRD5A2 | Prostate cancer active surveillance | Knock-in reporter or overexpression models with NKX3.1 readout |
| SRD5A1 | Androgen metabolism disorders | Overexpression and knockout in steroidogenic cells |
| SRD5A3 | Steroid 5alpha-reductase related biology | CRISPR knockout in cell lines |
| Comamonas testosteroni homolog | Bacterial steroid degradation | Bacterial gene knockout and complementation |
Benign prostatic hyperplasia and benign prostatic enlargement
Benign prostatic hyperplasia and benign prostatic enlargement are driven in part by androgen signaling, and 5alpha-reductase inhibitors that target GO:0047751 are used to reduce prostate size and symptoms. The pathophysiology involves dihydrotestosterone, the product of this enzyme activity, which promotes prostate cell proliferation.
Prostate cancer
In prostate cancer active surveillance, 5alpha-reductase inhibition has been studied as an intervention, with NKX3.1 expression proposed as an adjunct screening marker. The rationale is that reducing dihydrotestosterone production through inhibition of GO:0047751 may slow disease progression.
Developmental and reproductive biology
Steroid 5alpha-reductase activity in the rat epididymis changes during development, and phospholipid environment modulates the enzyme in vitro, linking GO:0047751 to reproductive tract maturation and function. These findings are relevant to understanding androgen-dependent development.
From 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SRD5A2 reduce dihydrotestosterone production? | SRD5A2 knockout cell line |
| Does a specific point mutation alter catalytic activity? | Point-mutation knock-in of SRD5A2 |
| Can a tagged enzyme be used to track localization? | Tagged knock-in of SRD5A1 or SRD5A2 |
| Does overexpression increase 5alpha-reduced steroid levels? | Overexpression of SRD5A1 or SRD5A2 |
| Does NKX3.1 expression change with 5alpha-reductase inhibition? | Knock-in reporter for NKX3.1 in prostate cells |
| Is the bacterial homolog functionally conserved? | Comamonas testosteroni gene knockout and complementation |
How to Study the 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADPH generation assay | Enzyme activity via NADPH production | Kinetic characterization of GO:0047751 |
| Steroid substrate conversion assay | Conversion of 3-oxo-5alpha-steroid to 3-oxo-delta(4)-steroid | Activity measurement in tissue extracts |
| 3D-QSAR modeling | Structure-activity relationships of inhibitors | Inhibitor design for 5alpha-reductase |
| Developmental activity profiling | Changes in enzyme activity with age | Epididymal development studies |
| Phospholipid modulation assay | Effect of membrane lipids on activity | In vitro regulation studies |
| NKX3.1 expression analysis | Adjunct marker for 5alpha-reductase inhibition | Prostate cancer active surveillance |
| Bacterial gene knockout | Loss of function of homolog | Comamonas testosteroni enzymology |
| Phosphorylation state analysis | Post-translational modification of enzyme | Rat liver enzyme regulation |
Enzyme activity assays
Direct measurement of 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity can be performed by monitoring NADPH production or substrate conversion using steroid substrates. Such assays have been used to study phosphorylation-dependent modulation in rat liver and phospholipid-dependent modulation in rat epididymis.
Inhibitor screening and 3D-QSAR
Steroidal 5alpha-reductase inhibitors can be evaluated using comparative 3D-QSAR models to predict binding and potency. These methods support drug discovery targeting GO:0047751.
Expression and developmental analysis
Developmental changes in enzyme activity can be assessed by measuring activity in tissues at different ages, as done in rat epididymis. Expression of related genes such as NKX3.1 can be monitored as an adjunct marker in prostate tissue.
Microbial genetics
The bacterial homolog from Comamonas testosteroni can be studied by gene knockout and protein characterization to understand conserved catalytic mechanisms.
How CRISPR Can Be Used to Study GO:0047751 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity
Knockout
CRISPR knockout of SRD5A1, SRD5A2, or SRD5A3 can eliminate 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity in cell models, enabling studies of androgen metabolism and inhibitor response. Knockout of the bacterial homolog in Comamonas testosteroni can confirm its role in steroid degradation.
Point Mutation
Point mutations can be introduced into SRD5A2 to test catalytic residues or to model naturally occurring variants that alter enzyme activity. Such models help dissect structure-function relationships of GO:0047751.
Knock-in
Knock-in of tagged versions of SRD5A1 or SRD5A2 allows tracking of enzyme localization and membrane association, which is relevant because phospholipid environment modulates activity. Knock-in reporters for NKX3.1 can be used to monitor responses to 5alpha-reductase inhibition.
Overexpression
Overexpression of SRD5A1 or SRD5A2 can increase flux through GO:0047751, raising dihydrotestosterone levels and providing a model for androgen-driven prostate biology. Overexpression studies also support inhibitor testing.
How EDITGENE Supports 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity Research
Researchers studying 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity-related genes often need to determine whether a candidate gene is causally involved in steroid metabolism, prostate disease, or developmental processes. EDITGENE provides CRISPR-based cell models and screening services to test these hypotheses with publication-ready rigor.
Contact EDITGENE today to design your custom CRISPR model for 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity research.
Frequently Asked Questions About 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity
What is GO:0047751?
GO:0047751 is the Gene Ontology molecular function term for 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity, which catalyzes the reaction: 3-oxo-5alpha-steroid + NADP+ = a 3-oxo-delta(4)-steroid + H+ + NADPH.
What does 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity do?
It removes hydrogens from a 3-oxo-5alpha-steroid and transfers them to NADP+, forming a 3-oxo-delta(4)-steroid, NADPH, and H+.
What genes are involved in 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity?
The main human genes are SRD5A1, SRD5A2, and SRD5A3, which encode steroid 5alpha-reductase isozymes. A bacterial homolog is found in Comamonas testosteroni.
What is another name for 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity?
Common synonyms include steroid 5alpha-reductase, testosterone 5alpha-reductase, 3-oxosteroid 5alpha-reductase, and cholestenone 5-alpha-reductase.
How is 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity regulated?
It can be modulated by phosphorylation state in rat liver and by the phospholipid environment in rat epididymis. Developmental changes also affect activity.
What diseases are linked to 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity?
It is linked to benign prostatic hyperplasia and prostate cancer, where 5alpha-reductase inhibitors are used or studied.
How can I study 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity in the lab?
You can measure NADPH production or substrate conversion, use 3D-QSAR for inhibitors, and perform developmental or phospholipid modulation assays.
What are 5alpha-reductase inhibitors?
They are compounds that block 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity, reducing dihydrotestosterone production, and are used for benign prostatic hyperplasia.
Is 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity conserved in bacteria?
Yes, Comamonas testosteroni has a characterized 3-ketosteroid-delta 4(5alpha)-dehydrogenase with analogous activity.
What cell models are available for GO:0047751 research?
CRISPR knockout, point-mutation, knock-in, and overexpression cell models for SRD5A genes are available from EDITGENE.
Conclusion
GO:0047751, 3-oxo-5-alpha-steroid 4-dehydrogenase (NADP+) activity, is a conserved molecular function that converts 3-oxo-5alpha-steroids to 3-oxo-delta(4)-steroids using NADP+. Its role in androgen metabolism makes it a key target in benign prostatic hyperplasia and prostate cancer research. Regulation by phosphorylation and membrane lipids adds layers of control that are relevant to physiology and drug action. CRISPR-based cell models and biochemical assays provide robust tools to dissect this activity and its therapeutic potential.
References
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- 3. Golf SW et al.. 1984. Rat liver 3-oxo-5 alpha-steroid delta 4-dehydrogenase. Modulation of enzyme activity by changes in phosphorylation state.. J Clin Chem Clin Biochem 22(11):705-9 PMID: 6527091
- 4. Yang JC et al.. 2017. Adjunct Screening of NKX3.1 Expression Supports 5α-Reductase Inhibition Intervention in Prostate Cancer Active Surveillance.. Eur Urol 72(4):507-508 PMID: 28454662
- 5. Florin C et al.. 1996. Comamonas testosteroni 3-ketosteroid-delta 4(5 alpha)-dehydrogenase: gene and protein characterization.. J Bacteriol 178(11):3322-30 PMID: 8655514
- 6. Cooke GM et al.. 1985. Modulation of epididymal delta 4-steroid 5 alpha-reductase activity in vitro by the phospholipid environment.. J Biol Chem 260(12):7489-95 PMID: 3997884
- 7. Thareja S. 2015. Steroidal 5α-Reductase Inhibitors: A Comparative 3D-QSAR Study Review.. Chem Rev 115(8):2883-94 PMID: 25785489
- 8. Scheer H et al.. 1980. Steroid delta 4-5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase in the rat epididymis during development.. Endocrinology 107(4):948-53 PMID: 6931815
