PRKG2 (Ab-126) Antibody

What is PRKG2 and what are the structural characteristics of the target epitope for the Ab-126 antibody?

PRKG2 (Protein Kinase, cGMP-Dependent, Type II), also known as cGKII, is a serine/threonine protein kinase that functions as a key mediator in cGMP signaling pathways. The protein contains several functional domains including leucine zippers at the N-terminus that facilitate homodimerization, an autoinhibitory domain, two cyclic nucleotide-binding sites (CNB-A and CNB-B) with different affinities for cGMP binding, and a catalytic domain spanning amino acid residues 459-718 .

The Ab-126 antibody specifically recognizes the region surrounding the serine 126 phosphorylation site with the amino acid sequence context G-V-S(p)-A-E . This site is located in the regulatory region of the protein, distinct from the catalytic domain. The phosphorylation status of this site is potentially significant for PRKG2 function, though its exact regulatory role requires further characterization through functional studies.

What are the validated applications for PRKG2 (Ab-126) Antibody and the optimal experimental conditions?

The PRKG2 (Ab-126) Antibody has been validated for multiple experimental applications with the following optimal conditions:

For optimal results in Western blotting, researchers should note that the observed molecular weight may appear as approximately 100 kDa, which differs from the calculated molecular weight of 84-87 kDa . This discrepancy is likely due to post-translational modifications affecting mobility during electrophoresis.

When designing experiments, it is critical to include appropriate positive controls (tissues known to express PRKG2, such as intestinal epithelium) and negative controls (tissues with minimal PRKG2 expression or antibody diluent only) to validate specificity of staining patterns .

What is the species reactivity profile of PRKG2 (Ab-126) Antibody and how can cross-reactivity issues be addressed?

The PRKG2 (Ab-126) Antibody demonstrates validated reactivity against:

• Human PRKG2

• Mouse PRKG2

• Rat PRKG2

This cross-species reactivity is supported by the high conservation of the target epitope region across mammalian species. The human and canine PRKG2 proteins exhibit 96.7% sequence identity over their entire length, with the lysine at position 534 being highly conserved among mammals .

To address potential cross-reactivity issues:

• Perform preliminary titration experiments to determine optimal antibody concentration for your specific sample type

• Include appropriate blocking steps using 3-5% BSA or normal serum from the same species as the secondary antibody

• Consider pre-absorption controls with the immunizing peptide when available

• Validate specificity by confirming band size in Western blot applications or by using PRKG2 knockout/knockdown samples as negative controls

How can the LanthaScreen™ Kinase assay be optimized for PRKG2 studies?

The LanthaScreen™ Kinase assay for PRKG2 requires specific optimization steps for reliable inhibitor screening and characterization. The protocol involves three key development stages:

• Determination of optimal kinase concentration:

  • Perform assay at high ATP concentration (1 mM)

  • Titrate kinase to determine EC80 value (concentration eliciting ~80% change in TR-FRET ratio)

• Determination of ATP Km,app:

  • Using optimal enzyme concentration, determine ATP EC50 value

  • For PRKG2, the ATP Km,app has been determined to be approximately 15 μM

• Re-optimization of kinase concentration at ATP Km,app:

  • Using the established ATP Km,app (15 μM), re-titrate kinase for optimal signal

Critical reagent preparation:

• Prepare cGMP stock solution (2 mM) by dissolving cGMP to 0.94 mg/mL

• Prepare 1x kinase reaction buffer by adding 2 mL of 5x buffer stock and 50 μL of 2 mM cGMP to 18 mL H2O (10 μM final cGMP concentration)

• EDTA: Stock = 500 mM, 1x = 10 mM, 2x = 20 mM

• Antibody: Stock = 6700 nM, 1x = 2 nM, 2x = 4 nM

This assay provides a robust platform for screening PRKG2 inhibitors and characterizing their potency and selectivity.

What is the role of PRKG2 in endochondral ossification and how do mutations affect skeletal development?

PRKG2 plays a critical role in endochondral ossification through its function as a molecular switch coupling the cessation of proliferation and the initiation of hypertrophic chondrocyte differentiation. The mechanism involves:

• C-type natriuretic peptide (CNP) binding to natriuretic peptide receptor-B (NPR-B)

• Increased intracellular cGMP levels

• Activation of PRKG2 (cGKII) homodimer

• Inhibition of the MAPK cascade (FGFR3/RAS/RAF/MEK/ERK) at the level of RAF

• Antagonism of fibroblast growth factor (FGF)-induced MAPK signaling

• Promotion of hypertrophic chondrocyte differentiation

The functional importance of PRKG2 in skeletal development is evidenced by a nonsense mutation identified in Dalmatian dogs that causes disproportionate dwarfism. This mutation introduces a premature stop codon at amino acid position 534 within the catalytic domain, resulting in:

• Shortened long bones, particularly in the limbs

• Irregular chondro-osseous junctions between growth cartilage and bone

• Disruption of the normal progression from proliferating chondrocytes to hypertrophic differentiation

In humans, five disease-causing PRKG2 alleles have been identified, leading to:

• PRKG2-related acromesomelic dysplasia (AMD4, MIM 619636)

• Possibly PRKG2-related spondylometaphyseal dysplasia (Pagnamenta type, MIM 619638)

• Shortened forearms and forelegs (mesomelia)

• Abnormal shortening of the bones in the hands and feet (acromelia)

These findings collectively demonstrate the essential role of functional PRKG2 in normal skeletal development across species.

What genetic associations have been identified between PRKG2 and human diseases?

Recent genetic studies have revealed several important disease associations with PRKG2:

• Primary Open-Angle Glaucoma (POAG):
  A genome-wide association study identified a novel low-frequency African-specific association in females at the locus rs116625313_PRKG2;RASGEF1B (females p = 2.85e-8, beta = 1.52 vs. males p = 0.35, beta = -0.59) . This finding suggests that PRKG2 may play a sex-specific role in glaucoma pathogenesis within specific ancestry groups.

• Skeletal Dysplasias:
  Mutations in PRKG2 cause PRKG2-related acromesomelic dysplasia (AMD4) and potentially PRKG2-related spondylometaphyseal dysplasia (Pagnamenta type) . These conditions are characterized by disproportionate skeletal growth and development.

• Potential Vascular Connections:
  Given PRKG2's role in signaling pathways that contribute to blood vessel morphogenesis, vasculature development, and regulation of endothelial cell proliferation, it may be involved in vascular aspects of ocular diseases .

These genetic associations highlight the diverse physiological roles of PRKG2 and suggest potential therapeutic targets for related conditions.

What strategies can be employed to validate phospho-specific detection using PRKG2 (Ab-126) Antibody?

To ensure accurate and reliable detection of PRKG2 phosphorylation at Ser126, researchers should implement the following validation strategies:

• Phosphatase treatment controls:

  • Split samples and treat one portion with lambda phosphatase

  • Compare antibody binding between treated and untreated samples

  • Loss of signal in phosphatase-treated samples confirms phospho-specificity

• Stimulation and inhibition experiments:

  • Treat cells with cGMP analogs (e.g., 8-Br-cGMP) to stimulate the pathway

  • Use kinase inhibitors to reduce phosphorylation

  • Monitor changes in signal intensity corresponding to treatment conditions

• Peptide competition assays:

  • Pre-incubate antibody with phosphorylated peptide (G-V-S(p)-A-E)

  • Compare with non-phosphorylated peptide pre-incubation

  • Specific blocking with phospho-peptide but not non-phospho-peptide confirms specificity

• Mutation analysis:

  • Generate S126A mutants that cannot be phosphorylated

  • Compare antibody binding between wild-type and mutant proteins

  • Loss of signal in the mutant confirms site-specific recognition

• Mass spectrometry validation:

  • Perform immunoprecipitation with the antibody

  • Analyze the precipitated protein by mass spectrometry

  • Verify the presence of the phosphorylated Ser126 residue

Implementing these validation techniques ensures that experimental observations truly reflect the phosphorylation status of PRKG2 at Ser126 rather than non-specific binding or artifacts.

How can researchers design experiments to investigate PRKG2's role in inhibiting the MAPK cascade?

To effectively study PRKG2's inhibitory effect on the MAPK cascade, particularly in the context of chondrocyte differentiation, researchers should consider the following experimental approach:

• Cell Model Selection:

  • Primary chondrocytes or chondrogenic cell lines (ATDC5, RCS)

  • Human or mouse mesenchymal stem cells undergoing chondrogenic differentiation

  • PRKG2 knockout/knockdown models as negative controls

• Pathway Activation:

  • Stimulate PRKG2 with cGMP analogs (8-Br-cGMP)

  • Activate NPR-B with C-type natriuretic peptide (CNP)

  • Monitor changes in cGMP levels using ELISA or fluorescent biosensors

• MAPK Cascade Analysis:

  • Use phospho-specific antibodies to detect phosphorylation states of:

    • RAF (target of PRKG2 inhibition)

    • MEK

    • ERK

  • Compare phosphorylation levels with and without PRKG2 activation

  • Western blotting or phospho-flow cytometry can quantify these changes

• Downstream Effect Measurement:

  • Monitor SOX9 activity (transcription factor affected by PRKG2)

  • Assess chondrocyte differentiation markers:

    • Collagen II (early)

    • Collagen X (hypertrophic)

    • Alkaline phosphatase activity

  • Quantify proliferation vs. differentiation markers

• Inhibitor Studies:

  • Use PRKG2 inhibitors to block its activity

  • Apply RAF inhibitors to bypass PRKG2's effect

  • Monitor pathway components to determine the precise point of PRKG2 action

A comprehensive experimental approach combining these elements will provide mechanistic insights into PRKG2's regulatory role in the MAPK signaling pathway during chondrocyte differentiation.

What are common issues when using PRKG2 (Ab-126) Antibody in Western blotting and how can they be resolved?

Researchers may encounter several challenges when using PRKG2 (Ab-126) Antibody in Western blotting. Here are common issues and their solutions:

Optimization protocol:

• Sample preparation:

  • Use RIPA buffer with protease and phosphatase inhibitors

  • Heat samples at 70°C for 10 minutes (not 95°C which may cause aggregation)

• Gel selection and transfer:

  • Use 8% gels for better resolution of PRKG2

  • Transfer at lower voltage for longer time (25V overnight at 4°C)

• Blocking and antibody incubation:

  • Block with 5% BSA (not milk, which contains phosphatases)

  • Dilute PRKG2 (Ab-126) Antibody in 1% BSA at 1:1000 initially

  • Incubate overnight at 4°C with gentle rocking

• Signal detection:

  • Use enhanced chemiluminescence with longer exposure times

  • Consider signal enhancement systems for weak signals

Implementing these troubleshooting strategies should result in successful detection of PRKG2 phosphorylated at Ser126 by Western blotting.

How can PRKG2 (Ab-126) Antibody be effectively used in multiplex immunofluorescence studies?

Multiplex immunofluorescence studies allow simultaneous detection of multiple targets, providing valuable spatial and contextual information. For effective use of PRKG2 (Ab-126) Antibody in such studies:

• Antibody panel selection:

  • Choose additional antibodies raised in different host species

  • Consider relevant targets in the PRKG2 pathway:

    • cGMP-related molecules (NPR-B, PDE5)

    • MAPK cascade components (RAF, MEK, ERK)

    • Chondrocyte markers (SOX9, Collagen II/X) for bone development studies

    • Cell type-specific markers for tissue context

• Custom conjugation options:
  Several fluorescent conjugation options are available for PRKG2 (Ab-126) Antibody:

  Fluorophore Categories	Available Options
  Traditional Dyes	FITC, TRITC, PacBlue, PacOrange, Cy3, Cy5
  Alexa Fluor	AF350, AF488, AF555, AF594, AF647, AF680, AF700, AF750
  iFluor Series	iFluor 488, 555, 594, 647, 680, etc.
  Tandem Dyes	PE, APC, PE/Cy5, PE/Cy7, APC/Cy7
  Proteins	HRP, Alkaline Phosphatase, Streptavidin

• Protocol optimization:

  • Use sequential staining for antibodies from the same species

  • Implement tyramide signal amplification for weak signals

  • Consider spectral unmixing for overlapping fluorophores

  • Use DAPI as nuclear counterstain for orientation

• Controls for multiplex studies:

  • Single-stained controls for each antibody

  • Fluorescence minus one (FMO) controls

  • Isotype controls for each species

  • Phosphatase-treated sections for phospho-specific antibody validation

• Image acquisition and analysis:

  • Use multispectral imaging systems for optimal separation

  • Perform automated quantification of co-localization

  • Analyze spatial relationships between PRKG2 and other pathway components

By carefully planning multiplex immunofluorescence studies with PRKG2 (Ab-126) Antibody, researchers can gain detailed insights into the spatial organization and contextual relationships of PRKG2 signaling in tissues.

How do results from PRKG2 knockout models compare with antibody inhibition studies?

Understanding the differences between genetic manipulation of PRKG2 and functional inhibition studies is crucial for comprehensive pathway analysis:

Genetic Models (Knockout/Knockdown):

• Phenotypic effects: Complete PRKG2 knockout in animals results in dwarfism with shortened limbs, irregular chondro-osseous junctions, and impaired endochondral ossification

• Cellular effects: Disruption of hypertrophic chondrocyte differentiation and persistent chondrocyte proliferation

• Molecular consequences: Sustained MAPK signaling and altered SOX9 activity

• Advantages: Complete absence of protein for clear phenotype assessment

• Limitations: Potential developmental compensation, difficult to assess temporal effects

Antibody-Based Inhibition Studies:

• Approach: Using antibodies against PRKG2 or its phosphorylation sites to modulate function

• Cellular effects: Temporary inhibition of specific phosphorylation events

• Advantages: Temporal control, ability to target specific phosphorylation sites (e.g., Ser126)

• Limitations: Incomplete inhibition, challenges with antibody delivery to intracellular targets

Comparative Analysis Framework:

Integrated Research Strategy:

This complementary approach provides more comprehensive insights than either method alone and helps distinguish between developmental versus acute functional roles of PRKG2.

What is known about sex-specific and ancestry-specific variations in PRKG2 function and their implications for disease?

Recent research has revealed important sex-specific and ancestry-specific variations in PRKG2 function with significant implications for disease pathogenesis:

Sex-Specific Variations:

• In the GBMI dataset, the variant rs116625313_PRKG2;RASGEF1B shows significant association with primary open-angle glaucoma (POAG) specifically in females (p = 2.85e-8, beta = 1.52) but not in males (p = 0.35, beta = -0.59)

• This suggests that PRKG2 may function differently in males versus females, potentially due to hormonal regulation or sex-specific expression patterns

• The sex-specific effect could explain some of the epidemiological differences observed in POAG prevalence between males and females

Ancestry-Specific Variations:

• The variant rs116625313_PRKG2;RASGEF1B is African-specific , highlighting the importance of diversity in genetic studies

• This finding underscores that some POAG risk variants may be ancestry-specific, sex-specific, or both

• Other genes showing ancestry-specific associations in the same study include TMEM167B, MIR3142HG-ATP10B, and ARMC4

Implications for Disease Understanding:

• These findings suggest that PRKG2 may contribute to disease pathogenesis through different mechanisms in different populations

• The intersection of sex and ancestry reveals complex genetic architecture underlying diseases like POAG

• The discovery of ancestry-specific variants highlights the critical importance of diverse representation in genetic studies

Research and Clinical Applications:

• Precision medicine approaches: Tailoring genetic screening based on sex and ancestry

• Drug development: Considering sex-specific and ancestry-specific responses to therapies targeting PRKG2

• Risk stratification: Incorporating these genetic insights into more accurate disease risk prediction models

• Experimental design: Ensuring representation of diverse populations and both sexes in research studies