GO:0047322 [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047322 describes the enzymatic activity that transfers a phosphate from ATP to [hydroxymethylglutaryl-CoA reductase (NADPH)], the rate-limiting enzyme of cholesterol synthesis.
• This kinase activity is synonymous with AMPK and STK29, and it is allosterically activated by nucleoside phosphates such as AMP.
• Phosphorylation of HMG-CoA reductase at serine 871 (in hamster) reduces its catalytic activity, providing a rapid brake on sterol synthesis.
• The reaction is reversible in principle, but in cells it is tightly controlled by hormonal and metabolic signals, including insulin and glucagon.
• Dysregulation of this phosphorylation axis is linked to cardiovascular disease, statin pharmacology, and metabolic disorders.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) are essential to dissect the causal role of this kinase activity in health and disease.
Description
The enzyme activity defined by GO:0047322, [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity, catalyzes the phosphorylation of HMG-CoA reductase using ATP as the phosphate donor. This modification is a central mechanism for the acute regulation of cholesterol biosynthesis, as HMG-CoA reductase is the rate-limiting enzyme in the mevalonate pathway. The kinase activity is often referred to as AMPK or STK29, reflecting its identity as a member of the AMP-activated protein kinase family. Because of its pivotal role in lipid metabolism, this activity has been a focus of research into hypercholesterolemia, cardiovascular disease, and the mechanism of action of statins. Understanding how this kinase activity is regulated and how it impinges on disease requires robust experimental models, and CRISPR gene editing has become a key tool for generating such models. This article integrates the QuickGO definition with verified PubMed literature to provide a research-grade overview of GO:0047322, its genes, functions, and methods for study.
[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity At A Glance
| GO ID | GO:0047322 |
|---|---|
| GO term | [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity |
| Ontology | molecular_function |
| Synonym | AMPK, STK29, HMG-CoA reductase kinase activity, reductase kinase activity |
| Major function | Phosphorylation of HMG-CoA reductase, leading to altered cholesterol synthesis |
| Reaction | [3-hydroxy-3-methylglutaryl-CoA reductase (NADPH)] + ATP = [3-hydroxy-3-methylglutaryl-CoA reductase (NADPH)] phosphate + ADP |
| Cofactors | ATP as phosphate donor; allosteric activation by nucleoside phosphates such as AMP |
| Regulation | Allosteric activation by AMP; hormonal control by insulin and glucagon |
| Disease relevance | Cardiovascular disease, statin response, metabolic disorders |
What Is GO:0047322?
GO:0047322 is a molecular function term describing the catalysis of the reaction: [3-hydroxy-3-methylglutaryl-CoA reductase (NADPH)] + ATP = [3-hydroxy-3-methylglutaryl-CoA reductase (NADPH)] phosphate + ADP. In simpler terms, it is the activity of an enzyme that adds a phosphate group to HMG-CoA reductase, using ATP as the phosphate donor. This phosphorylation event is a reversible post-translational modification that modulates the activity of HMG-CoA reductase, the key enzyme in cholesterol synthesis.
Why Is [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity Important in Cell Biology?
GO:0047322 is critically important because it provides a rapid, post-translational mechanism to control the rate-limiting step of cholesterol biosynthesis. By phosphorylating HMG-CoA reductase, this kinase activity can acutely reduce the production of mevalonate and downstream sterols, which is essential for maintaining lipid homeostasis. Dysregulation of this phosphorylation event has been implicated in hypercholesterolemia and cardiovascular disease, and it is a key target of statin drugs. Moreover, because the kinase is allosterically activated by AMP, it serves as a metabolic sensor that links cellular energy status to lipid synthesis. Understanding this activity is therefore fundamental for researchers in metabolism, cardiology, and pharmacology.
• Controls the rate-limiting enzyme of cholesterol synthesis, HMG-CoA reductase.
• Provides a rapid, reversible mechanism to adjust sterol production in response to hormonal and metabolic cues.
• Is allosterically activated by AMP, linking energy status to lipid metabolism.
• Is the target of statins, which are widely used to lower cholesterol and reduce cardiovascular risk.
• Dysregulation is associated with cardiovascular disease and metabolic syndrome.
• Plays a role in the mechanism of action of noncompetitive inhibitors such as dichloroacetate.
• Is a potential therapeutic target for modulating cholesterol levels in disease.
• Its study requires precise genetic models to separate its effects from other pathways.
• CRISPR screens can identify modifiers of this kinase activity and its downstream effects.
• Understanding its regulation may reveal new strategies for treating dyslipidemia.
Molecular Mechanism of [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity
Substrate Recognition and Binding
In simple terms: The kinase enzyme must first grab onto HMG-CoA reductase, the target protein, before it can add a phosphate.
The kinase activity defined by GO:0047322 specifically recognizes [hydroxymethylglutaryl-CoA reductase (NADPH)] as its substrate. This interaction is thought to involve the catalytic domain of HMG-CoA reductase, particularly the serine residue that is phosphorylated, such as serine 871 in the Syrian hamster enzyme. The binding is likely facilitated by the kinase's active site, which positions ATP and the substrate for efficient phosphate transfer. Allosteric activation by nucleoside phosphates, such as AMP, can enhance the kinase's affinity for its substrate.
Phosphoryl Transfer Reaction
In simple terms: The kinase takes a phosphate group from ATP and attaches it to HMG-CoA reductase.
The catalytic mechanism involves the transfer of the gamma-phosphate of ATP to a hydroxyl group on HMG-CoA reductase, forming a phosphoester bond and releasing ADP. This reaction is reversible in principle, but in cellular contexts it is tightly controlled. The phosphorylation of HMG-CoA reductase at specific serine residues, such as serine 871, leads to a decrease in its catalytic activity, thereby reducing the flux through the mevalonate pathway.
Allosteric Activation by Nucleoside Phosphates
In simple terms: Certain molecules like AMP can bind to the kinase and make it more active.
The kinase activity is allosterically activated by nucleoside phosphates, particularly AMP. This was demonstrated for the rat liver microsomal [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase, where AMP and other nucleoside phosphates enhanced the kinase activity. This allosteric regulation links the energy status of the cell to the control of cholesterol synthesis, as AMP levels rise when cellular energy is low, promoting phosphorylation and inhibition of HMG-CoA reductase.
Reversibility and Dephosphorylation
In simple terms: The phosphate can be removed by other enzymes, allowing the system to be reversible.
The phosphorylation of HMG-CoA reductase is reversible, and dephosphorylation is catalyzed by specific phosphatases. This reversibility allows for dynamic regulation of HMG-CoA reductase activity in response to changing physiological conditions. The balance between kinase and phosphatase activities determines the phosphorylation state of HMG-CoA reductase and thus its activity level.
Hormonal and Metabolic Regulation
In simple terms: Hormones like insulin and glucagon can affect how active this kinase is.
The activity of the kinase is subject to hormonal regulation. For example, glucagon and insulin can modulate the phosphorylation state of HMG-CoA reductase, thereby influencing cholesterol synthesis. This hormonal control ensures that cholesterol production is coordinated with the body's overall metabolic needs. Additionally, noncompetitive inhibitors such as dichloroacetate can affect the regulation of HMG-CoA reductase by this kinase.
Key Genes Involved in GO:0047322 [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity
The following genes and proteins are directly or indirectly involved in the [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity (GO:0047322) and its regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| HMGCR | Substrate of the kinase; rate-limiting enzyme in cholesterol synthesis | Phosphorylation by the kinase reduces its activity; target of statins |
| PRKAA1 | Catalytic subunit of AMPK, which can phosphorylate HMGCR | Mediates energy sensing and regulation of lipid metabolism |
| PRKAA2 | Catalytic subunit of AMPK, alternative isoform | Tissue-specific regulation of HMGCR phosphorylation |
| PRKAB1 | Regulatory subunit of AMPK | Modulates AMPK activity and substrate specificity |
| PRKAB2 | Regulatory subunit of AMPK | Modulates AMPK activity in different tissues |
| PRKAG1 | Regulatory subunit of AMPK | Allosteric activation by AMP |
| PRKAG2 | Regulatory subunit of AMPK | Mutations linked to cardiac disease; affects HMGCR regulation |
| PRKAG3 | Regulatory subunit of AMPK | Muscle-specific isoform; energy metabolism |
| STK11 | Upstream kinase that activates AMPK | Regulates AMPK and downstream HMGCR phosphorylation |
| CAB39 | Scaffold protein for AMPK activation | Required for AMPK-mediated HMGCR phosphorylation |
| STRADA | Upstream activator of AMPK | Links LKB1 to AMPK activation |
| PPP2CA | Phosphatase that dephosphorylates HMGCR | Reverses the kinase action |
| PPP2CB | Phosphatase catalytic subunit | Dephosphorylates HMGCR |
| INS | Hormone that regulates kinase activity | Modulates HMGCR phosphorylation via signaling |
| GCG | Hormone that regulates kinase activity | Glucagon affects HMGCR phosphorylation |
| SREBF2 | Transcription factor for cholesterol genes | Regulates HMGCR expression and feedback |
| SCAP | Cholesterol sensor | Regulates SREBP pathway and HMGCR levels |
| INSIG1 | Regulator of HMGCR degradation | Controls HMGCR stability |
How Is [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity Regulated?
The [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity is regulated at multiple levels. Allosterically, it is activated by nucleoside phosphates such as AMP, which bind to the kinase and enhance its activity. Hormonally, insulin and glucagon can modulate the phosphorylation state of HMG-CoA reductase, thereby influencing cholesterol synthesis. Additionally, the kinase activity is subject to feedback regulation by downstream sterols and is integrated with cellular energy status through AMPK signaling. Noncompetitive inhibitors such as dichloroacetate can also affect the regulation of HMG-CoA reductase by this kinase.
[hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| HMGCR | Hypercholesterolemia, cardiovascular disease | Knock-in of phospho-mimetic or phospho-deficient HMGCR |
| PRKAA1 | Metabolic syndrome, energy imbalance | Knockout of PRKAA1 in liver cells |
| PRKAA2 | Cardiovascular disease | Point mutation in PRKAA2 to alter kinase activity |
| PRKAG2 | Cardiac hypertrophy, Wolff-Parkinson-White syndrome | Knock-in of PRKAG2 mutations |
| PPP2CA | Dyslipidemia | Overexpression of PPP2CA to dephosphorylate HMGCR |
Cardiovascular Disease and Statin Response
Dysregulation of HMG-CoA reductase phosphorylation is linked to cardiovascular disease. Statins, which inhibit HMG-CoA reductase, are widely used to lower cholesterol and reduce cardiovascular risk. The kinase activity that phosphorylates HMG-CoA reductase can modulate the efficacy of statins and influence clinical outcomes in heart failure and chemotherapy-induced toxicity.
Metabolic Disorders
Alterations in the kinase activity may contribute to metabolic disorders such as hypercholesterolemia and metabolic syndrome. The allosteric activation by AMP links energy status to lipid metabolism, and disruption of this axis can lead to abnormal cholesterol levels.
Cancer and Chemotherapy Toxicity
Recent perspectives suggest that statin-mediated protection in chemotherapy-induced intestinal and cardiac toxicity involves modulation of HMG-CoA reductase activity and its phosphorylation. This highlights the broader role of this kinase activity in cellular stress responses and tissue protection.
From [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does phosphorylation of HMGCR at serine 871 regulate cholesterol synthesis? | Point mutation (S871A) knock-in cell line |
| What is the effect of AMPK knockout on HMGCR activity? | PRKAA1/PRKAA2 double knockout cells |
| Can a phospho-mimetic HMGCR reduce cholesterol levels? | Knock-in of S871D mutation |
| How does overexpression of the kinase affect lipid metabolism? | Overexpression of constitutively active AMPK |
| What genes modify the kinase activity? | CRISPR library screening |
| How does the kinase interact with HMGCR in live cells? | Tagged knock-in of HMGCR with GFP |
How to Study the [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro kinase assay | Phosphorylation of HMGCR by the kinase | Measuring specific activity of the kinase |
| Western blot with phospho-antibodies | Phosphorylation state of HMGCR | Assessing regulation in cells |
| CRISPR knockout screen | Genes affecting kinase activity or cholesterol synthesis | Identifying modifiers |
| Lipidomics | Cholesterol and intermediate levels | Functional consequences of kinase activity |
| qRT-PCR | Expression of HMGCR and related genes | Transcriptional regulation |
| Immunoprecipitation | Interaction between kinase and HMGCR | Studying complex formation |
| Metabolic flux analysis | Rate of cholesterol synthesis | Quantifying pathway activity |
| CRISPR activation (CRISPRa) | Overexpression of candidate genes | Gain-of-function studies |
Kinase Activity Assays
Direct measurement of [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity can be performed using in vitro kinase assays with purified HMG-CoA reductase and ATP. These assays quantify the transfer of radiolabeled phosphate from ATP to HMG-CoA reductase.
Phosphorylation-Specific Antibodies and Western Blotting
Phosphorylation of HMG-CoA reductase at specific residues, such as serine 871, can be detected using phospho-specific antibodies in Western blotting. This method allows assessment of the phosphorylation state in cells and tissues under different conditions.
CRISPR-Based Genetic Screens
Genome-wide CRISPR knockout or activation screens can identify genes that regulate the kinase activity or its downstream effects on cholesterol synthesis. These screens are powerful for discovering novel modifiers of the pathway.
Metabolic Labeling and Lipid Profiling
Measuring cholesterol synthesis rates using radiolabeled precursors (e.g., acetate) or mass spectrometry-based lipidomics can assess the functional consequences of altered kinase activity.
How CRISPR Can Be Used to Study GO:0047322 [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity
Knockout
CRISPR knockout of the kinase genes (e.g., PRKAA1, PRKAA2) can abolish the phosphorylation of HMG-CoA reductase, leading to increased cholesterol synthesis. Such models are useful to study the consequences of losing this regulatory axis.
Point Mutation
Introducing point mutations in HMGCR at the phosphorylation site (e.g., S871A) using CRISPR can prevent phosphorylation, while phospho-mimetic mutations (e.g., S871D) can mimic constitutive phosphorylation. These models help dissect the role of specific phosphorylation events.
Knock-in
Knock-in of tagged HMGCR (e.g., GFP or FLAG) allows visualization and immunoprecipitation of the substrate, facilitating studies of its interaction with the kinase and its subcellular localization.
Overexpression
CRISPR activation or lentiviral overexpression of constitutively active kinase can enhance HMGCR phosphorylation and reduce cholesterol synthesis, providing a gain-of-function model to study the pathway.
How EDITGENE Supports [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity Research
Researchers studying [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity-related genes often need to determine whether a candidate gene is causally involved in the regulation of cholesterol synthesis or disease. EDITGENE provides a comprehensive suite of CRISPR services to generate precisely engineered cell models, enabling rigorous functional studies.
Contact EDITGENE today to design your custom CRISPR model for [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity research.
Frequently Asked Questions About [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity
What is GO:0047322?
GO:0047322 is the Gene Ontology term for [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity, which catalyzes the phosphorylation of HMG-CoA reductase using ATP.
What genes are involved in [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity?
Key genes include HMGCR (the substrate), PRKAA1, PRKAA2, and other AMPK subunit genes that encode the kinase.
What is the function of [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity?
It phosphorylates HMG-CoA reductase, reducing its activity and thereby decreasing cholesterol synthesis.
How is [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity regulated?
It is allosterically activated by AMP and regulated by hormones such as insulin and glucagon.
What diseases are associated with [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity?
Cardiovascular disease, hypercholesterolemia, and metabolic disorders are linked to dysregulation of this activity.
What are the synonyms for [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity?
Synonyms include AMPK, STK29, HMG-CoA reductase kinase activity, and reductase kinase activity.
How can I study [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity in the lab?
You can use in vitro kinase assays, phospho-specific antibodies, and CRISPR knockout models.
What is the reaction catalyzed by [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase?
The reaction is: [3-hydroxy-3-methylglutaryl-CoA reductase (NADPH)] + ATP = [3-hydroxy-3-methylglutaryl-CoA reductase (NADPH)] phosphate + ADP.
Which residue of HMG-CoA reductase is phosphorylated by this kinase?
Serine 871 in the Syrian hamster enzyme is a key phosphorylation site.
How does CRISPR help in studying [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity?
CRISPR enables knockout, point mutation, knock-in, and overexpression models to dissect the pathway's function and regulation.
Conclusion
GO:0047322, [hydroxymethylglutaryl-CoA reductase (NADPH)] kinase activity, is a central regulator of cholesterol synthesis through phosphorylation of HMG-CoA reductase. Its allosteric activation by AMP and hormonal control make it a key metabolic sensor. Dysregulation is implicated in cardiovascular and metabolic diseases, and statins modulate this pathway. CRISPR-based models are indispensable for advancing our understanding of this activity and for developing new therapeutic strategies.
References
- 1. Ferrer A et al.. 1987. Allosteric activation of rat liver microsomal [hydroxymethylglutaryl-CoA reductase (NADPH)]kinase by nucleoside phosphates.. Biol Chem Hoppe Seyler 368(3):249-57 PMID: 3689494
- 3. Paramasivan K et al.. 2017. Regeneration of NADPH Coupled with HMG-CoA Reductase Activity Increases Squalene Synthesis in Saccharomyces cerevisiae.. J Agric Food Chem 65(37):8162-8170 PMID: 28845666
- 4. Omkumar RV et al.. 1994. Modulation of Syrian hamster 3-hydroxy-3-methylglutaryl-CoA reductase activity by phosphorylation. Role of serine 871.. J Biol Chem 269(9):6810-4 PMID: 8120043
- 5. Beg ZH et al.. 1982. Modulation of rat liver 3-hydroxy-3-methylglutaryl-CoA reductase activity by reversible phosphorylation.. Fed Proc 41(10):2634-8 PMID: 6286363
- 6. Stacpoole PW et al.. 1983. Regulation of rat liver hydroxymethylglutaryl coenzyme A reductase by a new class of noncompetitive inhibitors. Effects of dichloroacetate and related carboxylic acids on enzyme activity.. J Clin Invest 72(5):1575-85 PMID: 6630519
- 7. Arendt N et al.. 2025. Statin-mediated protection in chemotherapy-induced intestinal and cardiac toxicity: current perspectives.. Eur J Pharmacol 1007:178282 PMID: 41138833
- 8. Tousoulis D et al.. 2014. Statins in heart failure--With preserved and reduced ejection fraction. An update.. Pharmacol Ther 141(1):79-91 PMID: 24022031
