Phospho-EGFR (Tyr1110) Antibody

What is the functional significance of EGFR phosphorylation at Tyr1110 compared to other phosphorylation sites?

EGFR phosphorylation at Tyr1110 plays a distinct role in the complex signaling network of this receptor tyrosine kinase. While phosphorylation sites such as Tyr845 are involved in stabilizing the activation loop and Tyr992 mediates PLCγ binding and downstream signaling, Tyr1110 (sometimes historically referenced as Tyr1086) has been identified as one of the binding sites for the Grb2 adaptor protein .

The functional hierarchy of EGFR phosphorylation sites shows:

• Tyr845: Stabilizes activation loop and maintains enzyme activity; phosphorylated by c-Src

• Tyr992: Binds SH2 domain of PLCγ, activating PLCγ-mediated signaling

• Tyr1045: Creates docking site for c-Cbl, leading to receptor ubiquitination and degradation

• Tyr1068: Provides binding site for GRB2 adaptor protein

• Tyr1110/1086: Functions as an additional Grb2 binding site, potentially influencing MAPK pathway activation

• Tyr1148/Tyr1173: Provide docking sites for Shc scaffold protein, involved in MAP kinase signaling

Kinetic studies have shown that phosphorylation timing varies significantly between sites, with Tyr1110 showing relatively rapid phosphorylation (maximal at 1 minute post-EGF stimulation) compared to slower sites like Tyr998, indicating distinct regulatory functions .

How can researchers validate the specificity of Phospho-EGFR (Tyr1110) Antibody in their experimental system?

Validating antibody specificity is crucial for accurate phosphorylation analysis. A comprehensive validation approach includes:

Positive and negative control samples:

• Use EGF-stimulated cells (e.g., A431 or HepG2) as positive controls

• Include unstimulated cells or those treated with EGFR inhibitors as negative controls

• Western blot data indicates that treating A431 cells with EGF (100 ng/mL for 10 minutes) provides reliable positive control, while treatment with compound 56 (1 μM for 3 hours) serves as an effective negative control

Specificity verification methods:

• Phosphatase treatment: Treat half of your positive control lysate with lambda phosphatase to confirm signal loss

• Peptide competition: Pre-incubate antibody with immunizing phosphopeptide before using in assay

• Phosphorylation-deficient mutants: Test antibody against EGFR Y1110F mutant-expressing cells

• Multiple technique confirmation: Compare results across Western blot, immunohistochemistry, and ELISA

According to product specifications, Phospho-EGFR (Tyr1110) polyclonal antibody specifically detects endogenous levels of EGFR protein only when phosphorylated at Tyr1110 , with minimal cross-reactivity to other phosphorylation sites.

What are the optimal conditions for detecting EGFR phosphorylation at Tyr1110 in cell-based assays?

For optimal detection of EGFR phosphorylation at Tyr1110 in cell-based assays, researchers should consider:

Stimulation protocols:

• EGF concentration: 100 ng/mL is widely used for robust phosphorylation

• Time course: Optimal stimulation time is 5-10 minutes for maximum Tyr1110 phosphorylation

• Serum starvation: Prior serum deprivation (12-16 hours) enhances detection sensitivity

Experimental conditions for Western blot:

• Lysis buffer: Use buffer containing phosphatase inhibitors (sodium orthovanadate, sodium fluoride, β-glycerophosphate)

• Antibody dilution: 1:500-1:2000 for Western blot applications

• Sample preparation: Rapid sample processing to preserve phosphorylation status

Cell-based ELISA optimization:

• Cell density: Ensure consistent cell density (minimum 5000 cells per well)

• Fixation: 4% paraformaldehyde for 20 minutes at room temperature

• Normalization: Use total EGFR and GAPDH as controls for normalization

Quantitative data from lysate titration experiments demonstrates the sensitivity range, with signal-to-noise ratios increasing proportionally with protein concentration, showing P/N ratios of 2.7-82 across a concentration range of 0.039-5.0 μg .

How does phosphorylation of Tyr1110 relate to EGFR mutation status and response to EGFR-TKI therapy?

The relationship between EGFR Tyr1110 phosphorylation, mutation status, and tyrosine kinase inhibitor (TKI) response reveals important clinical correlations:

EGFR phosphorylation and mutation status:

• Studies have shown variable correlation between EGFR phosphorylation and mutation status

• While some research suggests phosphorylated EGFR is closely correlated with EGFR protein expression rather than mutation status, other studies show that cell lines with EGFR mutations exhibit constitutive phosphorylation

Clinical response prediction:

• Phosphorylation at specific tyrosine residues may serve as predictive biomarkers for EGFR-TKI therapy response

• Research examining pTyr1068 found it to be a significant predictor of response to EGFR-TKIs, particularly in wild-type EGFR patients (median PFS 4.2 months vs. 1.2 months, P < 0.001)

• While less studied than pTyr1068, Tyr1110 phosphorylation status may provide similar predictive value

Response in wild-type EGFR patients:

• Approximately 10-20% of patients with wild-type EGFR respond to TKIs

• Phosphorylation status may help identify this subgroup, as EGFR activation through phosphorylation can occur independently of mutation status

• Patients with both wild-type EGFR and positive pTyr1068 expression who responded to EGFR-TKIs showed median PFS of 15.6 months (95% CI: 7.28-23.9)

These findings suggest that phosphorylation analysis, including at Tyr1110, may complement mutation testing in predicting EGFR-TKI response.

What downstream signaling pathways are specifically activated by phosphorylation at EGFR Tyr1110?

Phosphorylation at EGFR Tyr1110 (also referred to as Tyr1086 in some literature) initiates specific downstream signaling cascades through protein recruitment:

Adaptor protein recruitment:

• Phosphorylated Tyr1110/1086 primarily serves as a binding site for the Grb2 adaptor protein

• This interaction differs from Tyr1068 (another Grb2 binding site) in terms of binding kinetics and potential downstream effects

Major signaling pathways activated:

• RAS-RAF-MEK-ERK pathway activation through Grb2 recruitment

• Potential influence on PI3K-AKT signaling through indirect mechanisms

• Possible contribution to STAT signaling, though less directly than other phosphorylation sites

Pathway crosstalk:

• Phosphorylation at Tyr1110 may work cooperatively with other sites to create a signaling network

• Research suggests coordinated phosphorylation involving multiple sites governs receptor trafficking and signaling outcomes

The specific binding partners and resulting signaling outcomes from Tyr1110 phosphorylation continue to be an active area of research, with evidence suggesting both overlapping and distinct functions compared to other C-terminal tyrosine phosphorylation sites.

What are the best experimental designs to study the relationship between EGFR Tyr1110 phosphorylation and receptor trafficking?

To investigate the relationship between EGFR Tyr1110 phosphorylation and receptor trafficking, consider these experimental approaches:

Time-course analysis:

• Examine phosphorylation kinetics at Tyr1110 alongside receptor internalization markers

• Compare with other phosphorylation sites involved in trafficking (e.g., Ser991, Tyr998)

• Research has shown that phosphorylation at different sites occurs with distinct kinetics, with some sites like Tyr998 accumulating more slowly than signaling-related sites

Mutagenesis studies:

• Generate phosphorylation-deficient Y1110F EGFR mutant

• Compare trafficking patterns with wild-type and other phospho-mutants

• Previous studies with S991A and Y998F mutants showed impaired receptor endocytosis despite normal ERK activation

Interaction analysis:

• Use co-immunoprecipitation to identify binding partners specific to phospho-Tyr1110

• Compare interactome differences between stimulated/unstimulated conditions

• Assess interactions with known trafficking regulators (e.g., CBL, AP-2)

Inhibitor studies:

• Apply specific pathway inhibitors to dissect phosphorylation dependencies

• Consider p38 MAPK inhibitors (e.g., SB-202190) which have been shown to block phosphorylation at sites involved in receptor trafficking

Fluorescence-based trafficking assays:

• Use fluorescently-labeled EGF ligand to track receptor internalization

• Correlate trafficking patterns with phosphorylation status using phospho-specific antibodies

• Time-lapse imaging to capture dynamic relationship between phosphorylation and trafficking events

Research has demonstrated that coordinated phosphorylation involving multiple sites (Tyr998, Ser991, Ser1039, and Thr1041) governs EGFR trafficking , suggesting that Tyr1110 should be studied within this broader context.

How can researchers differentiate between Tyr1110 and Tyr1086 phosphorylation sites in EGFR, given the historical referencing confusion?

The confusion between Tyr1110 and Tyr1086 in EGFR phosphorylation research requires careful attention to ensure accurate interpretation of results:

Understanding the nomenclature issue:

• Some antibodies detect "EGFR only when phosphorylated at Tyr1110, which site historically referenced as Tyr1086"

• This confusion appears to stem from different numbering systems used across research platforms and databases

Strategies for accurate site identification:

• Sequence verification:

  • Confirm the specific immunogen sequence used for antibody generation

  • Product information often states: "Synthetic phosphopeptide derived from human EGFR around the phosphorylation site of Tyrosine 1110"

• Cross-referencing literature:

  • When reviewing literature, note whether papers reference UniProt accession numbers

  • The full-length EGFR protein is referenced as P00533 in UniProt

• Mass spectrometry validation:

  • Use phospho-proteomics to unambiguously identify phosphorylation sites based on peptide mass

  • This approach can distinguish between closely positioned phosphorylation sites

• Multiple antibody approach:

  • Use antibodies from different sources that specifically target each site

  • Compare phosphorylation patterns across stimulation conditions

When conducting research, clearly document which nomenclature system is being used and consider providing sequence context of the phosphorylation site to avoid confusion in subsequent citations and comparisons.

What are the recommended protocols for using Phospho-EGFR (Tyr1110) Antibody in Western blotting?

For optimal results with Phospho-EGFR (Tyr1110) Antibody in Western blotting, follow these protocol recommendations:

Sample preparation:

• Lyse cells in buffer containing phosphatase inhibitors (10 mM sodium fluoride, 1 mM sodium orthovanadate, 10 mM β-glycerophosphate)

• Process samples rapidly on ice to preserve phosphorylation status

• Use positive controls: EGF-stimulated A431 or HepG2 cells show clear phospho-Tyr1110 signal

Gel electrophoresis and transfer:

• Use 7.5% or 4-12% gradient gels for optimal separation of high molecular weight EGFR (expected MW: 175-200 kDa)

• Transfer proteins to PVDF membrane at 30V overnight at 4°C for complete transfer of large proteins

Immunoblotting protocol:

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

• Dilute antibody 1:500-1:2000 in 5% BSA/TBST

• Incubate overnight at 4°C with gentle agitation

• Wash 4-5 times with TBST, 5 minutes each

• Apply appropriate HRP-conjugated secondary antibody

• Develop using enhanced chemiluminescence

Representative results:
Western blot analysis of HepG2 cells with Phospho-EGFR (Tyr1110) Polyclonal Antibody at dilution of 1:500 shows:

• Observed molecular weight: 175 kDa

• Calculated molecular weight: 134 kDa

Troubleshooting advice:

• High background: Increase washing steps and decrease antibody concentration

• Weak signal: Ensure robust EGFR phosphorylation in positive controls (100 ng/mL EGF for 5-10 minutes)

• Multiple bands: Verify specificity with phosphatase treatment of control samples

How does phosphorylation at EGFR Tyr1110 change in response to different EGF family ligands?

The phosphorylation pattern at EGFR Tyr1110 shows ligand-specific responses that can inform our understanding of receptor activation mechanisms:

Ligand-specific phosphorylation patterns:

• EGF is the prototypical ligand used to study Tyr1110 phosphorylation

• Different EGF family ligands (TGF-α, amphiregulin, betacellulin, epigen, epiregulin, HB-EGF) may induce varying degrees of phosphorylation at Tyr1110

• These ligands activate several signaling cascades by binding to EGFR and initiating receptor homo- and/or heterodimerization and autophosphorylation

Experimental approaches to measure ligand-specific effects:

• Dose-response analysis:

  • Treat cells with equivalent concentrations of different ligands

  • Monitor phosphorylation at Tyr1110 using Western blot or ELISA

  • Compare maximal response and EC50 values across ligands

• Time-course experiments:

  • Analyze phosphorylation kinetics following stimulation with different ligands

  • Determine if Tyr1110 shows distinct temporal patterns of activation

  • Compare with other phosphorylation sites to identify ligand-specific signatures

• Receptor dimerization analysis:

  • Different ligands may promote distinct EGFR-family receptor dimerization patterns

  • Correlate dimerization patterns with Tyr1110 phosphorylation intensity

Functional outcomes:

• Ligand-specific phosphorylation patterns may lead to distinct downstream signaling profiles

• The phosphorylated receptor recruits adapter proteins like GRB2 which activates complex downstream signaling cascades including RAS-RAF-MEK-ERK, PI3 kinase-AKT, PLCγ-PKC and STATs modules

• These differences may contribute to the diverse cellular responses observed with different EGFR ligands

What cell lines and treatment conditions serve as reliable positive controls for EGFR Tyr1110 phosphorylation?

Establishing reliable positive controls is essential for phospho-EGFR research. Based on published literature and product documentation, these cell lines and conditions provide consistent phospho-Tyr1110 EGFR signals:

Recommended cell lines:

• A431 cells: Human epidermoid carcinoma cells with high EGFR expression

  • Standard for EGFR phosphorylation studies

  • Show robust response to EGF stimulation

• HepG2 cells: Human hepatocellular carcinoma cells

  • Documented to show clear phospho-Tyr1110 signal in Western blot analysis

• MDA-MB-231: Triple-negative breast cancer cells

  • Show detectable EGFR phosphorylation changes with appropriate stimulation

• H1975: Non-small cell lung cancer cells with EGFR mutations

  • Exhibit constitutive EGFR phosphorylation that can be modulated

Optimal stimulation conditions:

• EGF concentration: 100 ng/mL is standard for robust phosphorylation

• Stimulation time: 5-10 minutes for maximal Tyr1110 phosphorylation

• Pre-treatment: Serum-starve cells for 12-16 hours before stimulation

• Negative control: Treatment with EGFR inhibitors such as compound 56 (1 μM for 3 hours)

Quantitative response data:
A properly stimulated positive control should show signal-to-noise ratios of:

• 2.7 at 0.039 μg lysate

• 29 at 0.63 μg lysate

• 82 at 5.0 μg lysate

Storage of positive control lysates:

• Prepare aliquots of stimulated cell lysates and store at -80°C

• Avoid repeated freeze-thaw cycles to preserve phosphorylation status

• Include phosphatase inhibitors in all buffers