Phospho-PTK2 (Ser843) Antibody

What is PTK2 and what is the significance of its phosphorylation at Ser843?

PTK2 (Protein Tyrosine Kinase 2), also known as focal adhesion kinase 1 (FAK1), functions in integrin signal transduction and in signaling downstream of numerous growth factor receptors, G-protein coupled receptors (GPCRs), EPHA2, netrin receptors, and LDL receptors. It forms multisubunit signaling complexes with SRC and SRC family members upon activation, leading to phosphorylation of additional tyrosine residues and creation of binding sites for scaffold proteins, effectors, and substrates .

The phosphorylation of PTK2 at Ser843 represents a critical regulatory modification that occurs very rapidly (within 5 seconds) in response to G protein-coupled receptor agonists such as bombesin, vasopressin, or bradykinin. Notably, this serine phosphorylation precedes the phosphorylation at Tyr397, which is the major autophosphorylation site, suggesting that Ser843 phosphorylation may function as an early regulatory event in PTK2 activation . This specific phosphorylation is mediated through a calcium-calmodulin-dependent protein kinase II (CaMKII) pathway, highlighting its importance in calcium-dependent signaling cascades .

What are the typical experimental applications for Phospho-PTK2 (Ser843) Antibody?

The Phospho-PTK2 (Ser843) Antibody is primarily used in Western blot (WB) and ELISA applications to detect the phosphorylation status of PTK2 at Ser843. For Western blot applications, the recommended dilution range is 1:500-1:1000 . The antibody can be applied to samples from human, mouse, and rat origins, making it versatile for comparative studies across these species .

Methodologically, this antibody is particularly valuable for:

• Monitoring rapid GPCR-induced signaling events

• Studying calcium-dependent kinase pathways

• Investigating cross-talk between different phosphorylation sites in PTK2

• Examining the temporal dynamics of PTK2 activation in response to various stimuli

• Assessing the effects of calcium modulators on focal adhesion signaling

How is the specificity of Phospho-PTK2 (Ser843) Antibody ensured in experimental settings?

The specificity of Phospho-PTK2 (Ser843) Antibody is ensured through rigorous purification processes. According to the product information, antibodies are produced by immunizing rabbits with synthetic phosphopeptide and KLH conjugates specific to the Ser843 phosphorylation site. The antibodies are then purified through a two-step process:

• Affinity-chromatography using epitope-specific phosphopeptide to select antibodies that recognize the phosphorylated form

• Chromatography using non-phosphopeptide to remove non-phospho specific antibodies that might cross-react with the unphosphorylated form of the protein

For experimental validation of specificity, researchers should consider including appropriate controls:

• Comparing phosphorylated versus non-phosphorylated samples

• Using phosphatase treatment to remove phosphorylation

• Including samples with site-directed mutations at Ser843

• Utilizing peptide competition assays with the immunizing phosphopeptide

How does G protein-coupled receptor activation trigger PTK2 phosphorylation at Ser843, and what methods best capture this rapid signaling event?

GPCR activation leads to an extremely rapid (within 5 seconds) increase in PTK2 phosphorylation at Ser843 through a calcium-dependent signaling pathway. The mechanistic sequence involves:

• GPCR activation by agonists such as bombesin, vasopressin, or bradykinin

• Increase in intracellular calcium concentration [Ca²⁺]ᵢ

• Calcium binding to calmodulin

• Activation of calcium/calmodulin-dependent protein kinase II (CaMKII)

• Direct phosphorylation of PTK2 at Ser843 by activated CaMKII

To effectively capture and study this rapid signaling event, researchers should employ the following methodological approaches:

• Ultra-rapid cell lysis techniques: Using specialized buffers that can halt signaling within milliseconds

• Time-course experiments: With very short time intervals (1-5 seconds) to capture the earliest phosphorylation events

• Live-cell imaging: Using phospho-specific biosensors to monitor phosphorylation dynamics in real-time

• Calcium chelators and CaMKII inhibitors: Such as BAPTA, thapsigargin, and KN93 to validate the calcium-dependent pathway

• Phosphoproteomic analysis: Using techniques like SILAC (stable isotope labeling with amino acids in cell culture) combined with mass spectrometry for temporal profiling

Research has demonstrated that treatments affecting any step in this pathway—including agents that prevent calcium increases (thapsigargin, BAPTA), interfere with calmodulin function (trifluoperazine, W13, W7), or block CaMKII activation (KN93) or expression (siRNA)—abrogate the GPCR-induced rapid phosphorylation at Ser843 .

What is the relationship between PTK2 phosphorylation at Ser843 and cancer therapy resistance, and how can the antibody be used to investigate this phenomenon?

PTK2 has emerged as a critical regulator of cancer cell responses to chemotherapy. Research indicates that PTK2-mediated phosphorylation events, including potentially at Ser843, play important roles in cancer therapy resistance through various mechanisms:

• Regulation of autophagy proteins: PTK2 induces phosphorylation of autophagy-related proteins like ATG3, leading to their degradation in response to cancer chemotherapeutic agents

• Impaired therapeutic response: The degradation of autophagy factors mediated by PTK2 impedes cancer cells' response to chemotherapy

• Cell survival pathways: PTK2 can activate the phosphoinositide 3-kinase-AKT1 pathway by binding with the PIK3R/p85 subunit, inducing survival signals and preventing cancer cell death

Phospho-PTK2 (Ser843) Antibody can be used to investigate these phenomena through:

• Comparative phosphorylation studies: Analyzing the Ser843 phosphorylation status in treatment-resistant versus treatment-sensitive cancer cells

• Combination therapy testing: Evaluating the impact of PTK2 inhibitors on Ser843 phosphorylation and subsequent chemosensitivity

• Temporal dynamics analysis: Monitoring the kinetics of Ser843 phosphorylation in response to chemotherapy agents

• Pathway analysis: Using the antibody in combination with inhibitors of calcium signaling to determine if the GPCR-calcium-CaMKII pathway contributes to therapy resistance

Research has shown that PTK2 inhibition combined with DNA-damaging agents significantly decreases cancer cell viability and colony formation. For example, the PTK2 inhibitor PF-573228, but not inhibitors of SRC or EGFR, enhanced etoposide-induced inhibition of cell proliferation and dramatically decreased colony formation in combination with etoposide or cisplatin .

What methodological considerations should be addressed when using Phospho-PTK2 (Ser843) Antibody in phosphoproteomic studies?

When incorporating Phospho-PTK2 (Ser843) Antibody in phosphoproteomic studies, researchers should address several critical methodological considerations:

• Sample preparation optimization:

  • Rapid sample processing to preserve phosphorylation status

  • Inclusion of phosphatase inhibitors (e.g., sodium orthovanadate, sodium fluoride, β-glycerophosphate)

  • Standardized lysis conditions to ensure consistent extraction of phosphorylated proteins

• Enrichment strategies:

  • Consider using the antibody for immunoprecipitation prior to mass spectrometry

  • Combine with phosphotyrosine-specific antibodies to capture the full spectrum of PTK2 phosphorylation

  • Implement titanium dioxide (TiO₂) or immobilized metal affinity chromatography (IMAC) for global phosphopeptide enrichment

• Validation approaches:

  • Confirm specificity using phosphatase treatment controls

  • Verify phosphorylation site assignment with synthetic phosphopeptides

  • Implement orthogonal techniques such as Phos-tag SDS-PAGE for mobility shift validation

• Quantification methods:

  • Consider stable isotope labeling approaches (SILAC, iTRAQ, TMT) for accurate quantification

  • Implement label-free quantification with appropriate normalization strategies

  • Utilize multiple reaction monitoring (MRM) for targeted quantification of Ser843 phosphopeptides

• Data analysis considerations:

  • Account for potential neutral loss during mass spectrometric analysis of phosphopeptides

  • Implement appropriate statistical approaches for phosphosite occupancy calculation

  • Consider using kinase substrate prediction algorithms to identify other potential CaMKII targets

How can Phospho-PTK2 (Ser843) Antibody be used in cancer immunotherapy research?

Phospho-PTK2 (Ser843) Antibody can serve as a valuable tool in cancer immunotherapy research, particularly given recent findings linking PTK2 expression with immunotherapy outcomes. A comprehensive pan-cancer analysis of 33 human cancers revealed relationships between FAK/PTK2 and cancer immunotherapy . Researchers can utilize this antibody to:

• Evaluate immune checkpoint correlations: Investigate associations between PTK2 Ser843 phosphorylation status and expression of immune checkpoint markers across different cancer types

• Assess tumor immune microenvironment: Examine how PTK2 phosphorylation relates to intratumoral immune invasion patterns

• Predict immunotherapy response: Explore whether Ser843 phosphorylation status correlates with tumor mutation burden (TMB) and microsatellite instability (MSI), which are established biomarkers for immunotherapy response

• Study signaling pathway interactions: Investigate how PTK2 phosphorylation at Ser843 influences immune modulator expression, including immune inhibitors, immune stimulators, and MHC molecules

Methodologically, researchers should consider:

• Multiplexed immunofluorescence approaches to simultaneously detect phospho-PTK2 and immune markers

• Single-cell analysis to capture heterogeneity in phosphorylation patterns across different cell populations within the tumor microenvironment

• Integration with spatial transcriptomic data to correlate phosphorylation patterns with gene expression profiles in specific tumor regions

What is the significance of PTK2 Ser843 phosphorylation in the context of combination therapy development?

PTK2 Ser843 phosphorylation may play a significant role in determining cancer cell responses to combination therapies. Research findings indicate:

• Enhanced therapeutic efficacy: PTK2 inhibition combined with DNA-damaging agents shows synergistic effects in reducing cancer cell viability

• Mechanism of action: PTK2 inhibition prevents the degradation of autophagy-related proteins (such as ATG3), potentially enhancing the efficacy of chemotherapeutic agents

• Clinical relevance: Several PTK2 inhibitors are currently being evaluated in clinical trials, with combination regimens showing promising results

A methodological framework for investigating the role of Ser843 phosphorylation in combination therapy includes:

Research has shown that among several tyrosine kinase inhibitors, PTK2 inhibitors had significantly stronger effects on cancer cell colony formation when combined with DNA-damaging agents . This suggests that targeting the pathways regulating PTK2 phosphorylation, including potentially at Ser843, could be a promising strategy for enhancing chemotherapy efficacy.

How does the phosphorylation pattern of PTK2 at Ser843 compare with other key phosphorylation sites, and what methods can resolve potential crosstalk?

PTK2 contains multiple phosphorylation sites that regulate its activity and signaling capabilities. The phosphorylation at Ser843 exhibits distinct characteristics compared to other key sites:

To investigate potential crosstalk between different phosphorylation sites on PTK2, researchers can employ the following methodological approaches:

• Multiplexed phospho-specific antibody analysis:

  • Simultaneous detection of phosphorylation at Ser843, Tyr397, and other sites using multiplexed Western blotting or immunofluorescence

  • Temporal profiling to establish the sequence of phosphorylation events

  • Correlation analysis to identify interdependencies between different phosphorylation sites

• Site-directed mutagenesis studies:

  • Generation of phospho-mimetic (S843D/E) and phospho-deficient (S843A) mutants

  • Analysis of how mutation at Ser843 affects phosphorylation at other sites

  • Functional assessment of mutants to determine the impact on PTK2 activity and signaling

• Kinase inhibitor approaches:

  • Selective inhibition of CaMKII to block Ser843 phosphorylation

  • Assessment of how CaMKII inhibition affects tyrosine phosphorylation at Tyr397 and other sites

  • Combination with SRC family kinase inhibitors to understand pathway intersection

• Mass spectrometry-based phosphoproteomics:

  • Global analysis of PTK2 phosphorylation sites and their dynamic changes

  • Quantification of site occupancy under different conditions

  • Network analysis to identify co-regulated phosphorylation sites

What are the optimal sample preparation protocols for detecting PTK2 Ser843 phosphorylation in different experimental systems?

Optimal sample preparation is critical for successful detection of PTK2 Ser843 phosphorylation. Based on the research findings and technical specifications, the following protocols are recommended:

For cell culture systems:

• Stimulation timing: Given the rapid and transient nature of Ser843 phosphorylation, precise timing is crucial. For GPCR-mediated phosphorylation, collect samples as early as 5 seconds after stimulation

• Rapid lysis procedure:

  • Aspirate media quickly and immediately add ice-cold lysis buffer

  • Use a lysis buffer containing: 50 mM Tris-HCl (pH 7.5), 150 mM NaCl, 1% Triton X-100, 0.1% SDS, 0.5% sodium deoxycholate

  • Supplement with phosphatase inhibitors: 50 mM NaF, 5 mM Na₃VO₄, 10 mM Na₄P₂O₇, 10 mM β-glycerophosphate

  • Include protease inhibitor cocktail

• Processing considerations:

  • Keep samples on ice throughout processing

  • Clear lysates by centrifugation at 14,000 × g for 15 minutes at 4°C

  • Determine protein concentration using Bradford or BCA assay

  • Store aliquots at -80°C with minimal freeze-thaw cycles

For tissue samples:

• Sample collection: Flash-freeze tissues in liquid nitrogen immediately after collection

• Homogenization protocol:

  • Pulverize frozen tissue under liquid nitrogen using a mortar and pestle

  • Homogenize in lysis buffer (as described above) using a tissue homogenizer

  • Use approximately 5 ml of lysis buffer per gram of tissue

• Special considerations:

  • Process tissue samples rapidly to prevent phosphatase activity

  • Consider using phospho-protein stabilization buffers during collection

  • For immunohistochemistry applications, use phospho-specific fixation protocols

Western blot optimization:

When using the Phospho-PTK2 (Ser843) Antibody in Western blot applications, follow these guidelines:

• Use a dilution range of 1:500-1:1000 as recommended

• Load 20-50 μg of total protein per lane

• Consider using Phos-tag™ SDS-PAGE for enhanced separation of phosphorylated species

• Include positive controls (cells treated with ionomycin or GPCR agonists)

• Include negative controls (samples treated with lambda phosphatase)

How can researchers address potential cross-reactivity concerns when using Phospho-PTK2 (Ser843) Antibody?

Cross-reactivity is a common concern when using phospho-specific antibodies. Researchers can address this issue through several approaches:

• Validation controls:

  • Phosphatase treatment: Treating a portion of the sample with lambda phosphatase should eliminate the signal if it's specific to phosphorylated Ser843

  • Peptide competition assay: Pre-incubating the antibody with the immunizing phosphopeptide (sequence: R-G-S(p)-I-D) should block specific binding

  • Knockout/knockdown validation: Using PTK2 knockout or knockdown samples as negative controls

  • Phospho-site mutants: Comparing wild-type PTK2 with S843A mutant samples

• Optimizing experimental conditions:

  • Blocking: Use 5% BSA in TBS-T rather than milk (which contains phosphoproteins)

  • Antibody dilution: Start with the recommended 1:500-1:1000 range and optimize if needed

  • Incubation conditions: Overnight incubation at 4°C may yield better specificity than shorter incubations

  • Washing: Implement stringent washing steps (4-6 washes with TBS-T)

• Signal verification strategies:

  • Sequential immunoblotting: Strip and reprobe with total PTK2 antibody

  • Parallel blotting: Run identical samples on separate blots for phospho and total protein

  • Size verification: Confirm that the detected band appears at the expected molecular weight for PTK2 (125 kDa)

  • Stimulus-response correlation: Verify that the signal responds appropriately to treatments known to modulate Ser843 phosphorylation

• Advanced confirmation approaches:

  • Immunoprecipitation followed by Western blotting

  • Mass spectrometry validation of the phosphorylation site

  • Comparison with alternative phospho-specific antibodies from different vendors

What are the key considerations for quantitative analysis of PTK2 Ser843 phosphorylation in experimental and clinical samples?

Quantitative analysis of PTK2 Ser843 phosphorylation requires careful attention to several methodological aspects:

• Normalization strategies:

  • Normalize phospho-PTK2 (Ser843) to total PTK2 protein levels to account for expression variations

  • Include housekeeping protein controls (β-actin, GAPDH) for loading normalization

  • Consider using stain-free technology or total protein normalization for more reliable quantification

  • For clinical samples, normalize to appropriate reference tissues or cell types

• Statistical considerations:

  • Perform experiments with sufficient biological replicates (minimum n=3)

  • Apply appropriate statistical tests based on data distribution

  • Consider using non-parametric tests for clinical samples with potential heterogeneity

  • Report both statistical significance and effect sizes

• Dynamic range and linearity:

  • Establish the linear detection range for both phospho-PTK2 and total PTK2

  • Create a standard curve using recombinant phosphorylated and non-phosphorylated proteins

  • Ensure that sample concentrations fall within the linear range of detection

  • Consider using fluorescence-based Western blotting for wider dynamic range

• Temporal considerations in experimental designs:

  • For GPCR-mediated phosphorylation, include very early time points (5, 10, 30 seconds)

  • Extend time courses to capture both rapid phosphorylation and potential dephosphorylation kinetics

  • Control experimental timing precisely to minimize variability

  • Consider using automated systems for consistent sample processing

• Clinical sample-specific considerations:

  • Account for tumor heterogeneity through multiple sampling or single-cell approaches

  • Consider pre-analytical variables (ischemia time, fixation method, storage conditions)

  • Implement batch controls and normalization for multi-center studies

  • Correlate phosphorylation status with clinical parameters and outcomes

How might studying PTK2 Ser843 phosphorylation contribute to understanding spatial regulation of focal adhesion signaling?

The spatial regulation of focal adhesion signaling involves complex protein interactions and localized signaling events. Investigating PTK2 Ser843 phosphorylation could provide valuable insights into these spatial aspects through the following research approaches:

• Advanced imaging methodologies:

  • Super-resolution microscopy (STORM, PALM, SIM) to visualize the nanoscale organization of phosphorylated PTK2

  • FRET-based biosensors to monitor PTK2 Ser843 phosphorylation in living cells with spatial and temporal resolution

  • Correlative light and electron microscopy to link phosphorylation events with ultrastructural features

  • Lattice light-sheet microscopy for 4D imaging of phosphorylation dynamics during cell migration

• Spatial proteomics applications:

  • Proximity labeling techniques (BioID, APEX) to identify proteins near phosphorylated PTK2

  • Biochemical fractionation to determine the subcellular distribution of Ser843-phosphorylated PTK2

  • Local proteomics at focal adhesions using laser capture microdissection

  • Spatial mapping of phosphorylation events during adhesion assembly and disassembly

• Mechanobiology perspectives:

  • Investigation of how mechanical forces regulate PTK2 Ser843 phosphorylation

  • Analysis of how Ser843 phosphorylation affects mechanotransduction

  • Correlation of phosphorylation patterns with traction force microscopy data

  • Substrate rigidity modulation to assess mechanical regulation of phosphorylation

• Computational modeling approaches:

  • Agent-based modeling of focal adhesion dynamics incorporating PTK2 phosphorylation states

  • Reaction-diffusion models of kinase and phosphatase activities within adhesion complexes

  • Integration of spatial phosphoproteomic data with structural information

  • Prediction of phosphorylation-dependent protein interaction networks

What emerging technologies might enhance detection and functional analysis of PTK2 Ser843 phosphorylation?

Several emerging technologies hold promise for advancing the detection and functional analysis of PTK2 Ser843 phosphorylation:

• Single-cell phosphoproteomics:

  • Mass cytometry (CyTOF) with phospho-specific antibodies

  • Single-cell Western blotting for heterogeneity analysis

  • Microfluidic-based single-cell phosphoprotein detection

  • Integration with single-cell transcriptomics for multi-omic analysis

• CRISPR-based technologies:

  • Base editing to create specific phospho-site mutations (S843A or S843D)

  • CRISPR activation/inhibition systems to modulate PTK2 expression

  • CRISPR screens to identify regulators of Ser843 phosphorylation

  • Optogenetic CRISPR systems for temporal control of PTK2 expression or mutation

• Biosensor development:

  • Genetically encoded FRET-based sensors specific for Ser843 phosphorylation

  • Split fluorescent protein complementation assays for phosphorylation-dependent interactions

  • Nanobody-based fluorescent reporters for live-cell imaging

  • Phospho-specific circularly permuted fluorescent proteins

• Artificial intelligence applications:

  • Deep learning for image analysis of phospho-PTK2 localization patterns

  • Machine learning algorithms to predict phosphorylation-dependent protein interactions

  • Neural networks for integrating phosphorylation data with other cellular parameters

  • AI-assisted experimental design for phosphoproteomic studies

• Organoid and 3D culture systems:

  • Analysis of PTK2 Ser843 phosphorylation in patient-derived organoids

  • 3D cell culture models to study phosphorylation in physiologically relevant contexts

  • Microfluidic organ-on-chip platforms with real-time phosphorylation monitoring

  • Co-culture systems to investigate phosphorylation in heterotypic cell interactions

How can researchers integrate PTK2 Ser843 phosphorylation data with broader phosphoproteomic and multi-omic datasets?

Integrating PTK2 Ser843 phosphorylation data with broader datasets requires sophisticated computational and experimental approaches:

• Multi-level data integration strategies:

  • Correlation of Ser843 phosphorylation with other PTK2 phosphorylation sites

  • Network analysis connecting PTK2 phosphorylation with upstream regulators and downstream effectors

  • Pathway enrichment analysis to identify biological processes associated with Ser843 phosphorylation

  • Integration with transcriptomic data to identify phosphorylation-dependent gene expression changes

• Systems biology frameworks:

  • Construction of ordinary differential equation (ODE) models incorporating Ser843 phosphorylation

  • Bayesian network analysis to infer causal relationships in signaling networks

  • Constraint-based modeling to predict phenotypic consequences of altered phosphorylation

  • Multi-scale modeling linking molecular events to cellular behaviors

• Temporal multi-omics approaches:

  • Time-resolved phosphoproteomics paired with transcriptomics and metabolomics

  • Trajectory analysis to map signaling dynamics following stimulation

  • Identification of phosphorylation-dependent transcriptional and metabolic changes

  • Inference of time-dependent regulatory networks

• Clinical data integration considerations:

  • Correlation of PTK2 Ser843 phosphorylation with patient outcomes

  • Integration with genomic alterations (mutations, copy number variations)

  • Association with response to specific therapies, particularly PTK2 inhibitors

  • Development of predictive models incorporating phosphorylation status

• Data visualization and exploration tools:

  • Interactive visualization platforms for multi-dimensional phosphoproteomic data

  • Computational workflows for integrating heterogeneous data types

  • Web-based resources for sharing and exploring integrated datasets

  • Customized analytical pipelines for PTK2-focused investigations