PRKAA1/PRKAA2 (Ab-487) Antibody

What is the PRKAA1/PRKAA2 (Ab-487) Antibody and what does it detect?

The PRKAA1/PRKAA2 (Ab-487) Antibody is a polyclonal antibody generated in rabbits that specifically recognizes the phosphorylated serine residue at position 487 in human AMPKα1 (PRKAA1). According to manufacturer specifications, this antibody was developed using a synthetic peptide corresponding to the sequence around amino acids 485-489 (S-G-S-V-S) from human AMPKα1 . This site is located within the "ST loop" (serine/threonine-rich loop) in the C-terminal domain of the α1 subunit and represents a critical regulatory phosphorylation site that modulates AMPK activity .

The antibody specifications typically include:

This antibody serves as a valuable research tool for investigating the inhibitory regulation of AMPK, particularly in contexts of insulin signaling, metabolic disorders, and cardiovascular diseases .

What is the significance of AMPKα1 Ser487 phosphorylation in cellular metabolism?

Phosphorylation of AMPKα1 at Ser487 represents a critical inhibitory mechanism that regulates AMPK activity with significant implications for cellular metabolism. AMPK functions as an energy sensor that typically activates catabolic pathways and inhibits anabolic processes during energy deficit.

The inhibitory phosphorylation at Ser487 creates a regulatory checkpoint with several metabolic consequences:

• Prevents Thr172 phosphorylation by upstream kinases like LKB1, thereby inhibiting AMPK activation

• Creates cross-talk between growth factor signaling (via Akt and PKC) and energy-sensing pathways (via AMPK)

• Contributes to reduced AMPK activity in insulin-resistant states, as AMPKα1 Ser487 phosphorylation is inversely correlated with insulin sensitivity in human muscle

• Affects AMPK's ability to regulate key metabolic processes including fatty acid synthesis, cholesterol synthesis, and glucose metabolism

This phosphorylation event is especially relevant in pathological conditions characterized by metabolic dysfunction. In states of overnutrition, increased Ser487 phosphorylation may contribute to reduced AMPK activity, compromising its ability to maintain metabolic homeostasis and potentially contributing to insulin resistance and obesity .

How do different kinases regulate AMPKα1 Ser487 phosphorylation?

AMPKα1 Ser487 phosphorylation is regulated by multiple upstream kinases that respond to different physiological stimuli:

• Akt/PKB: Phosphorylates Ser487 in response to insulin or IGF-1 stimulation in various tissues including heart, adipose tissue, vascular smooth muscle cells, and tumor cell lines. This creates an inhibitory cross-talk mechanism where growth factor signaling can suppress AMPK activity .

• Protein Kinase C (PKC): VEGF-stimulated AMPKα1 Ser487 phosphorylation is sensitive to PKC inhibitors. PKC activation using phorbol esters or PKC overexpression stimulates AMPKα1 Ser487 phosphorylation. Both purified PKC and Akt phosphorylate AMPKα1 Ser487 in vitro with similar efficiency .

• PKA (cAMP-dependent protein kinase): Recombinant PKA can also phosphorylate AMPKα1 Ser487 in vitro, suggesting multiple regulatory inputs to this site .

• Autophosphorylation: Interestingly, while AMPKα1 Ser487 is primarily phosphorylated by upstream kinases, the equivalent site on AMPKα2 (Ser491) appears to be modified predominantly by autophosphorylation .

This multi-kinase regulation allows for integration of different physiological signals to modulate AMPK activity in a context-dependent manner. The activation of these upstream kinases in disease states may contribute to pathological AMPK inhibition .

What are the applications of PRKAA1/PRKAA2 (Ab-487) Antibody in research?

The PRKAA1/PRKAA2 (Ab-487) Antibody can be utilized in multiple experimental techniques to investigate AMPK regulation:

• Western Blotting: Detects phosphorylated AMPKα1 at Ser487 in cell or tissue lysates. Western blot analysis of PRKAA1 has been demonstrated using this antibody with 293 cell lysates either non-transfected or transiently transfected with the PRKAA1 gene .

• Immunohistochemistry (IHC): Visualizes the distribution of phosphorylated AMPKα1 in tissue sections. The antibody has been validated for IHC-P (paraffin-embedded tissues), as demonstrated by its application to formalin-fixed and paraffin-embedded human breast carcinoma tissue .

• ELISA: Enables quantitative measurement of phosphorylated AMPKα1 levels. Commercial ELISA kits are available for monitoring the activation or function of AMPK pathways in human cell lysates .

Each application requires specific optimization parameters:

These methods allow researchers to investigate AMPKα1 Ser487 phosphorylation in various physiological and pathological contexts, including metabolic disorders, cardiovascular diseases, and cancer research .

How does Ser487 phosphorylation mechanistically inhibit AMPK activity?

The inhibitory effect of Ser487 phosphorylation on AMPK activity occurs through a specific molecular mechanism:

• Prevention of activating phosphorylation: Phosphorylation at Ser487 in the ST loop of AMPKα1 reduces subsequent phosphorylation by upstream kinases (particularly LKB1) at the activating site, Thr172. Since Thr172 phosphorylation is essential for AMPK activation, this inhibition effectively suppresses AMPK activity .

• Conformational changes: Structurally, Ser487 phosphorylation likely induces conformational changes in the AMPK complex that render the Thr172 site less accessible to upstream activating kinases. This creates an elegant regulatory mechanism where growth signals can rapidly suppress AMPK-mediated catabolic processes .

• Isoform specificity: Interestingly, while Akt phosphorylates AMPKα1 at Ser487, the equivalent site on AMPKα2 (Ser491) is not an Akt target and is modified instead by autophosphorylation. This suggests differential regulation of the two catalytic subunit isoforms, potentially allowing for tissue-specific or context-dependent modulation of AMPK activity .

• Functional consequences: Stimulation of HEK-293 cells with IGF-1 causes reduced subsequent Thr172 phosphorylation and activation of AMPK-α1 in response to the AMPK activators A769662 and the Ca²⁺ ionophore A23187, with these effects being dependent on Akt activation and Ser487 phosphorylation .

This molecular mechanism provides a critical link between anabolic signaling pathways (growth factors via Akt/PKC) and catabolic regulation (energy sensing via AMPK), allowing cells to coordinate these opposing processes appropriately .

What experimental controls should be used when studying AMPKα1 Ser487 phosphorylation?

Robust experimental design for studying AMPKα1 Ser487 phosphorylation requires multiple controls:

Positive Controls:

• Cell treatments that increase Ser487 phosphorylation:

  • Insulin or IGF-1 stimulation (activates Akt pathway)

  • Phorbol esters such as PMA (activate PKC)

  • VEGF treatment (activates PKC pathway)

Negative Controls:

• Pharmacological inhibitors:

  • PKC inhibitors (for PKC-mediated phosphorylation)

  • Akt inhibitors (for Akt-mediated phosphorylation)

• Genetic approaches:

  • Expression of AMPKα1 Ser487Ala mutant (cannot be phosphorylated at this site)

  • siRNA/shRNA knockdown of upstream kinases

Specificity Controls:

• Antibody validation:

  • Pre-absorption with immunizing peptide

  • Testing on knockout/knockdown samples

• Parallel detection systems:

  • Total AMPK antibody (for normalization)

  • Phospho-Thr172 AMPK antibody (to confirm inverse relationship)

Experimental System Controls:

• For cell culture:

  • Time course experiments to capture dynamic changes

  • Serum starvation to establish baseline

• For animal models:

  • Appropriate genetic backgrounds

  • Age and sex-matched controls

These controls are essential for establishing the specificity of observed effects and for distinguishing between Akt-mediated and PKC-mediated phosphorylation events, which may have different physiological implications .

What is the relationship between AMPKα1 Ser487 phosphorylation and insulin resistance?

AMPKα1 Ser487 phosphorylation has emerged as a potential molecular link between insulin signaling and metabolic dysfunction:

• Clinical correlation: AMPKα1 Ser487 phosphorylation is inversely correlated with insulin sensitivity in human muscle, suggesting that increased inhibitory phosphorylation may contribute to reduced AMPK activity in insulin-resistant states .

• Pathophysiological mechanism: In states of overnutrition associated with insulin resistance and obesity, elevated Ser487 phosphorylation may underlie the reduced AMPK activity consistently reported in metabolic and vascular tissues .

• Animal models: Experimental evidence supports this connection:

  • Aortae from mice with experimental diabetes exhibit increased basal and IGF-1-stimulated phosphorylation of Akt and AMPKα1 Ser487, with concomitant reduced AMPKα Thr172 phosphorylation

  • Glucose infusion in rats increases AMPKα1/α2 Ser487/491 phosphorylation

  • Transfection of a murine muscle cell line with AMPKα2 Ser491Ala (preventing phosphorylation) attenuates the inhibition of insulin signaling by PMA

• PKC connection: PKC activation is associated with insulin resistance and obesity, and PKC can phosphorylate AMPKα1 at Ser487. This suggests that PKC-mediated phosphorylation of this site may underlie the reduced AMPK activity in insulin-resistant metabolic and vascular tissues .

This relationship highlights a potential feed-forward mechanism in insulin resistance: initial insulin resistance leads to compensatory hyperinsulinemia, which could increase Akt-mediated Ser487 phosphorylation, further reducing AMPK activity and exacerbating metabolic dysfunction .

How does AMPKα1 Ser487 phosphorylation relate to PRKAG2 cardiomyopathy?

PRKAG2 cardiomyopathy and AMPKα1 Ser487 phosphorylation represent different regulatory aspects of AMPK function in cardiac tissue:

• PRKAG2 cardiomyopathy: Mutations in the PRKAG2 gene, encoding the γ2 regulatory subunit of AMPK, cause a distinct cardiomyopathy characterized by cardiac hypertrophy, preexcitation, and glycogen deposition . This condition has been recapitulated in transgenic mice overexpressing mutant PRKAG2 N488I in the heart (TGγ2N488I) .

• AMPKα subunit involvement: Although the primary mutation is in the γ2 subunit, the catalytic α subunits play crucial roles in mediating the phenotype:

  • Mice overexpressing a dominant-negative α2 subunit (TGα2DN) show inhibition of α2 but not α1 subunit-associated AMPK activity

  • When crossed with TGγ2N488I mice, the TGα2DN transgene reduced the disease phenotype, suggesting that AMPK complexes containing the α2 rather than the α1 subunit are the primary mediators of the effects of PRKAG2 mutations

• Connection to Ser487 phosphorylation: While the research results don't directly address AMPKα1 Ser487 phosphorylation in PRKAG2 cardiomyopathy, several potential connections exist:

  • The inhibitory phosphorylation at Ser487 may serve as a counterregulatory mechanism in conditions of inappropriate AMPK activation, such as that caused by PRKAG2 mutations

  • The differential roles of α1 and α2 subunits in cardiac pathology suggest that α1-specific regulation (including Ser487 phosphorylation) may have distinct implications for cardiac function

• Metabolic consequences: Both regulatory mechanisms affect cardiac energy metabolism:

  • PRKAG2 mutations lead to glycogen accumulation, but this glycogen can serve as an energy source during exercise stress

  • AMPKα1 Ser487 phosphorylation reduces AMPK activity, potentially affecting its role in regulating cardiac metabolism and energy homeostasis

Understanding the interplay between these regulatory mechanisms may provide insights into the complex role of AMPK in cardiac physiology and pathology .

How should Western blot protocols be optimized for detecting phosphorylated AMPK using the PRKAA1/PRKAA2 (Ab-487) Antibody?

Optimizing Western blot protocols for phospho-specific detection of AMPK using the PRKAA1/PRKAA2 (Ab-487) Antibody requires careful attention to multiple experimental parameters:

Sample Preparation:

• Rapid sample processing to preserve phosphorylation status:

  • Flash-freeze tissues immediately after collection

  • Lyse cells directly in hot SDS sample buffer when possible

  • Maintain samples at 4°C during processing

• Phosphatase inhibitor cocktails must be included in all lysis buffers

• Protein determination methods should be compatible with phosphatase inhibitors

Gel Electrophoresis and Transfer:

• Use freshly prepared gels to ensure consistent separation

• Consider gradient gels (4-15%) for optimal resolution of AMPK (~62 kDa)

• PVDF membranes are generally preferred for phospho-epitope detection

• Transfer conditions should be optimized for proteins in the 50-75 kDa range

Antibody Incubation:

• Recommended dilution: 1:500-1:1000 for Western blotting

• Primary antibody incubation: Overnight at 4°C provides optimal signal-to-noise ratio

• Blocking solution: 5% BSA in TBST is preferred over milk for phospho-epitopes

• Secondary antibody: Anti-rabbit HRP at 1:5000-1:10000 dilution

Data Analysis and Validation:

• Always run total AMPK detection in parallel for normalization

• Include positive controls: insulin-stimulated samples (increases Ser487 phosphorylation)

• Include negative controls: samples treated with Akt/PKC inhibitors

• For definitive validation, include samples expressing AMPKα1 Ser487Ala mutant

Troubleshooting Guide:

Western blot analysis using this antibody has been validated with 293 cell lysates, particularly comparing non-transfected cells and cells transiently transfected with the PRKAA1 gene .

How can AMPK modulators be used as controls in experiments using the PRKAA1/PRKAA2 (Ab-487) Antibody?

AMPK modulators provide valuable experimental tools when used alongside the PRKAA1/PRKAA2 (Ab-487) Antibody to probe the regulatory mechanisms of AMPK:

AMPK Activators:

• AICAR (5-aminoimidazole-4-carboxamide ribonucleoside): Converted intracellularly to ZMP, which mimics AMP and activates AMPK

  • Expected effect: May increase AMPKα1/α2 Ser487/491 autophosphorylation in some cell types

  • Application: Use to distinguish between autophosphorylation and upstream kinase-mediated phosphorylation

• A-769662: Direct AMPK activator that binds to the β subunit

  • Expected effect: Activates AMPK but stimulation with IGF-1 causes reduced subsequent Thr172 phosphorylation and activation of AMPK-α1 in response to A-769662

  • Application: Useful for investigating the inhibitory effect of Ser487 phosphorylation on AMPK activation

• Calcium ionophores (A23187): Increase intracellular calcium, activating CaMKK-β which phosphorylates AMPK at Thr172

  • Expected effect: Similar to A-769662, IGF-1 pre-treatment reduces AMPK activation by A23187

  • Application: Tests the CaMKK-β pathway of AMPK activation

Upstream Kinase Modulators:

• Akt inhibitors (e.g., MK-2206):

  • Expected effect: Decreased Ser487 phosphorylation

  • Application: Confirm Akt-dependent phosphorylation mechanisms

• PKC inhibitors:

  • Expected effect: Reduced VEGF-stimulated AMPKα1 Ser487 phosphorylation

  • Application: Distinguish between Akt and PKC-mediated phosphorylation

• Phorbol esters (PMA):

  • Expected effect: Increased Ser487 phosphorylation via PKC activation

  • Application: Positive control for PKC-mediated phosphorylation

Metabolic Stress Inducers:

• Glucose deprivation:

  • Expected effect: AMPK activation via increased AMP:ATP ratio

  • Application: Determine if metabolic stress affects Ser487 phosphorylation

• Hypoxia:

  • Expected effect: AMPK activation

  • Application: Study the interplay between stress-induced activation and inhibitory phosphorylation

Using these modulators in combination with the PRKAA1/PRKAA2 (Ab-487) Antibody allows researchers to dissect the complex regulatory mechanisms controlling AMPK activity in different physiological and pathological contexts .

What techniques can be combined with PRKAA1/PRKAA2 (Ab-487) Antibody detection to comprehensively study AMPK signaling?

A comprehensive investigation of AMPK signaling requires integration of multiple techniques beyond antibody-based detection:

Complementary Antibody-Based Techniques:

• Multiplex phospho-protein analysis:

  • Simultaneously detect multiple phosphorylation sites (Thr172, Ser487, Ser491)

  • Monitor both activating and inhibitory phosphorylation events

  • Track downstream targets of AMPK (ACC, Raptor, TSC2)

• Proximity ligation assay (PLA):

  • Visualize interactions between AMPK and its upstream kinases/phosphatases

  • Determine subcellular localization of these interactions

  • Detect conformational changes induced by Ser487 phosphorylation

Functional Assays:

• AMPK activity assays:

  • Direct measurement of AMPK catalytic activity using SAMS peptide phosphorylation

  • Compare activity levels with phosphorylation status determined by antibody detection

  • PKC activation is associated with reduced AMPK activity, as inhibition of PKC increases AMPK activity and phorbol esters inhibit AMPK

• Metabolic flux analysis:

  • Measure glycolysis and mitochondrial respiration using Seahorse technology

  • Correlate metabolic patterns with AMPK phosphorylation status

  • Assess functional consequences of Ser487 phosphorylation on cellular metabolism

Genetic Approaches:

• CRISPR/Cas9 gene editing:

  • Generate Ser487Ala mutants to prevent inhibitory phosphorylation

  • Create phosphomimetic mutants (Ser487Asp) to simulate constitutive phosphorylation

  • TGα2DN mice crossed with TGγ2N488I mice demonstrate the utility of genetic approaches in studying AMPK subunit-specific effects

• Isoform-specific knockdowns:

  • Selectively target α1 vs α2 subunits to determine isoform-specific functions

  • Target upstream kinases to determine relative contributions to Ser487 phosphorylation

Advanced Imaging:

• FRET-based AMPK sensors:

  • Real-time monitoring of AMPK conformational changes in living cells

  • Correlate with Ser487 phosphorylation detected by immunofluorescence

  • Track spatiotemporal dynamics of AMPK regulation

• Super-resolution microscopy:

  • Visualize subcellular localization of phosphorylated AMPK

  • Determine colocalization with upstream regulators and downstream targets

Integration of these techniques with antibody-based detection provides a comprehensive view of AMPK regulation, enabling researchers to connect molecular events to physiological outcomes .

What are the recommended validation methods for confirming specificity of phospho-specific AMPK antibodies?

Rigorous validation of phospho-specific antibodies like the PRKAA1/PRKAA2 (Ab-487) Antibody is essential for reliable research outcomes:

Genetic Validation Approaches:

• Site-directed mutagenesis:

  • Test antibody reactivity against Ser487Ala mutants (should show no signal)

  • Test reactivity against phosphomimetic mutants (Ser487Asp/Glu)

  • Compare with wild-type AMPK under various stimulation conditions

• Knockout/knockdown systems:

  • Verify antibody specificity using AMPK α1-null samples

  • Compare signal in cells with siRNA-mediated knockdown of AMPK α1

  • This approach is particularly important for distinguishing α1 vs α2 isoform specificity

Biochemical Validation Methods:

• Peptide competition assays:

  • Pre-incubate antibody with immunizing phosphopeptide (should block specific signal)

  • Pre-incubate with non-phosphorylated version of the same peptide (should not affect specific signal)

  • Pre-incubate with irrelevant phosphopeptides (should not affect specific signal)

• Phosphatase treatment:

  • Treat samples with lambda phosphatase before immunoblotting

  • Should eliminate signal from phospho-specific antibody

  • Parallel detection with total AMPK antibody should be unaffected

Stimulation-Based Validation:

• Pharmacological modulation:

  • Verify increased signal after treatments known to enhance Ser487 phosphorylation (insulin, IGF-1, phorbol esters)

  • Confirm decreased signal after treatment with Akt or PKC inhibitors

  • Demonstrate inverse relationship with Thr172 phosphorylation

• Time-course analysis:

  • Monitor phosphorylation dynamics after stimulation

  • Correlation with activation/inhibition of upstream kinases

  • Western blot analysis comparing non-transfected cells with cells transiently transfected with the PRKAA1 gene provides a good validation approach

Cross-Validation with Alternative Methods:

• Mass spectrometry:

  • Direct identification and quantification of phosphorylation at Ser487

  • Correlation with antibody-based detection methods

  • Identification of potential additional phosphorylation sites

• Alternative antibody sources:

  • Compare results using antibodies from different suppliers targeting the same epitope

  • Cross-validate with antibodies raised using different immunization strategies

  • Both RayBiotech and Cusabio offer antibodies targeting this phosphorylation site

Thorough validation using multiple approaches ensures reliable interpretation of results in complex biological systems .

What are the emerging research directions for studying AMPKα1 Ser487 phosphorylation?

The study of AMPKα1 Ser487 phosphorylation continues to evolve with several promising research directions:

• Therapeutic targeting: Given the inverse correlation between AMPKα1 Ser487 phosphorylation and insulin sensitivity in human muscle , developing approaches to selectively modulate this phosphorylation site could offer therapeutic benefits for metabolic disorders. Strategies might include:

  • Small molecule inhibitors of specific upstream kinases

  • Compounds that induce conformational changes preventing Ser487 phosphorylation

  • Peptide-based inhibitors that mimic the ST loop region

• Tissue-specific regulation: The differential regulation of AMPKα1 Ser487 and AMPKα2 Ser491 suggests isoform-specific functions that may vary between tissues . Future research should address:

  • Tissue-specific expression patterns of AMPK isoforms and upstream kinases

  • Differential physiological consequences of α1 vs α2 inhibition in various tissues

  • Tissue-specific phosphatases that may counteract Ser487 phosphorylation

• Pathological significance: While correlations with insulin resistance have been established , a broader understanding of AMPKα1 Ser487 phosphorylation in human disease states is needed:

  • Role in cardiovascular diseases beyond PRKAG2 cardiomyopathy

  • Contribution to neurodegenerative conditions where energy metabolism is dysregulated

  • Potential involvement in cancer metabolism and tumor progression

• Integration with other post-translational modifications: AMPK is regulated by multiple PTMs beyond Ser487 phosphorylation. Research examining:

  • Cross-talk between different phosphorylation sites

  • Interplay with other modifications (acetylation, ubiquitination, etc.)

  • Comprehensive PTM profiling in health and disease states

• Development of advanced research tools:

  • Improved phospho-specific antibodies with enhanced specificity and sensitivity

  • Biosensors for real-time monitoring of AMPK conformational changes in live cells

  • Advanced animal models with tissue-specific expression of phospho-mutants

These emerging directions will continue to enhance our understanding of how AMPKα1 Ser487 phosphorylation contributes to metabolic regulation and disease pathogenesis .

How do research findings on AMPKα1 Ser487 phosphorylation translate to potential clinical applications?

Research on AMPKα1 Ser487 phosphorylation has several potential clinical applications:

• Biomarker development: The inverse correlation between AMPKα1 Ser487 phosphorylation and insulin sensitivity in human muscle suggests potential as a biomarker for:

  • Insulin resistance and metabolic syndrome

  • Risk stratification for type 2 diabetes

  • Monitoring therapeutic responses to metabolic interventions

• Therapeutic target identification: Understanding the regulatory mechanisms of Ser487 phosphorylation reveals potential intervention points:

  • PKC inhibitors may reduce pathological AMPK inhibition, as PKC activation is associated with insulin resistance and obesity

  • Akt pathway modulators could influence the cross-talk between growth signaling and energy sensing

  • Compounds that specifically prevent Ser487 phosphorylation without affecting other AMPK regulatory mechanisms

• Precision medicine approaches: The complex regulation of AMPK by multiple upstream kinases suggests opportunities for personalized interventions:

  • Patient stratification based on predominant mechanisms of AMPK dysregulation

  • Tailored therapeutic approaches targeting specific upstream kinases

  • Combination therapies addressing multiple regulatory pathways

• Cardiovascular applications: Based on insights from PRKAG2 cardiomyopathy research and the role of AMPK in cardiovascular health:

  • Targeted therapies for specific cardiopathies involving AMPK dysregulation

  • Cardioprotective strategies based on optimizing AMPK activity

  • Prevention of cardiovascular complications in metabolic disorders

• Diagnostic tools development:

  • Development of clinical assays to measure tissue-specific AMPK phosphorylation status

  • Imaging techniques to visualize AMPK activity in various tissues

  • Genetic screening for variants affecting AMPK regulation