Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody

What are EPHA2, EPHA3, and EPHA4 receptors and what is their significance in cell signaling?

EPHA2, EPHA3, and EPHA4 belong to the Eph subfamily, which represents the largest group of receptor protein tyrosine kinases identified to date. These receptors play crucial roles in cell signaling, particularly in processes such as cell adhesion, migration, and axon guidance during development . The Eph receptors mediate bidirectional signaling that regulates cell behavior and tissue organization upon binding to their ephrin ligands.

In embryonic stem cells (ESCs), EPHA2 is the major EPH receptor family member and the most abundant receptor kinase, with EPHA4, EPHB4, EPHB2, and EPHB3 expressed at lower levels . These receptors are particularly important in the central nervous system function and development, where they guide axonal pathfinding and establish tissue boundaries .

The unique bidirectional signaling capability of these receptors enables them to mediate both repulsive and attractive cell-cell interactions, contributing to their fundamental roles in tissue compartmentalization and boundary formation during embryonic development . Phosphorylation at specific tyrosine residues, including Y588/596, is critical for regulating receptor activity and downstream signaling cascades.

What is the importance of Y588/596 phosphorylation sites in EPH receptors?

The Y588/596 phosphorylation sites in EPHA2, EPHA3, and EPHA4 receptors represent critical regulatory elements that control receptor activation and downstream signaling. These specific tyrosine residues are located in a region that plays a key role in signal transduction after receptor activation.

Phosphorylation at these sites typically occurs following ephrin ligand binding and represents an active signaling state of the receptor . When studying EPHA2 in embryonic stem cells, researchers have observed that tyrosine phosphorylation (including at Y588/596) supports expression of pluripotency factors like NANOG and KLF4, while antagonizing ERK1/2 signaling that would otherwise promote differentiation .

The phosphorylation status at Y588/596 can be dynamically regulated during biological processes. For instance, during ESC differentiation, FGF4 signaling can lead to changes in EPHA2 phosphorylation patterns, shifting from activating tyrosine phosphorylation to inhibitory serine/threonine phosphorylation . This phosphorylation switch serves as a molecular mechanism controlling the transition from pluripotency to differentiation.

Monitoring these specific phosphorylation events using the Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody provides researchers with a valuable tool to assess receptor activation states and understand the regulation of downstream signaling pathways in various biological contexts.

What experimental applications is the Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody suitable for?

The Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody has been validated for multiple experimental applications, making it a versatile tool for researchers studying Eph receptor signaling:

Western Blotting (WB):

• Recommended dilution: 1:500-1:2000

• Allows detection of phosphorylated receptors at their expected molecular weight of approximately 112 kDa

• Enables quantitative assessment of phosphorylation changes in response to various stimuli

Immunofluorescence (IF):

• Recommended dilution: 1:200-1:1000

• Permits visualization of the spatial distribution of phosphorylated receptors within cells

• Successfully used in cell lines such as HeLa cells, as demonstrated in datasheet images

Enzyme-Linked Immunosorbent Assay (ELISA):

• Allows for quantitative measurement of phosphorylation levels in cell lysates

• The In-Cell ELISA format enables analysis of phosphorylation in intact cells without disrupting cellular architecture

The antibody demonstrates reactivity with human, mouse, and rat samples, providing flexibility for comparative studies across species . Its polyclonal nature offers robust signal detection, though careful validation with appropriate controls is recommended for each specific application.

The antibody has been successfully applied in various research contexts, including stem cell studies examining the role of EPHA2 in pluripotency maintenance and infectious disease research investigating EPHA2 as a receptor for Pneumocystis β-glucans .

How should researchers prepare samples for optimal antibody performance?

Proper sample preparation is crucial for detecting phosphorylated Eph receptors with maximum sensitivity and specificity. The following guidelines are recommended based on established protocols:

For Western Blotting:

• Cell Lysis and Protein Extraction:

  • Use RIPA lysis buffer containing both phosphatase and protease inhibitors to prevent dephosphorylation during sample processing

  • Keep samples cold throughout preparation to maintain phosphorylation status

  • Process samples quickly to minimize phosphatase activity

• Sample Loading and Running:

  • Typically, 5-20 μg of total protein per lane is sufficient (5 μg was used successfully in published protocols)

  • Use freshly prepared samples when possible, as freeze-thaw cycles can affect phosphorylation

• Antibody Incubation:

  • Dilute primary antibody in 5% BSA in TBST rather than milk, as milk contains phosphatases

  • Incubate overnight at 4°C for optimal results with recommended dilutions (1:500-1:2000)

For Immunofluorescence:

• Fix cells using appropriate methods that preserve phosphoepitopes

• Include blocking steps to minimize background signal

• Use the recommended antibody dilution (1:200-1:1000)

For Phosphorylation Analysis in Stimulation Experiments:

• For synchronized stimulation, spin plates at 500g for 5 minutes after applying stimuli

• Collect samples at multiple time points (15, 30, 60, 90 minutes) to capture phosphorylation dynamics

• Include proper controls: unstimulated cells, cells treated with phosphatase, and positive controls (e.g., cells stimulated with ephrin ligands)

For In-Cell ELISA:

• Optimize cell density for the specific cell type being studied

• Ensure consistent cell numbers across wells for accurate comparisons

• Include wells for normalization to total protein or cell number

For all applications, it is crucial to include appropriate positive and negative controls and to validate antibody specificity in your specific experimental system.

What are the recommended storage conditions and shelf life for Phospho-EPHA2/EPHA3/EPHA4 antibodies?

Proper storage of the Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody is essential for maintaining its activity and specificity over time. Based on manufacturer guidelines, the following storage recommendations apply:

Storage Buffer:

• The antibody is typically supplied in PBS containing 50% glycerol, 0.5% BSA, and 0.02% sodium azide

• This formulation helps maintain antibody stability and prevents microbial contamination

Temperature Requirements:

• For long-term storage, -20°C is recommended

• Avoid repeated freeze-thaw cycles, which can degrade antibody quality and reduce specificity

• For short-term use, small working aliquots can be stored at 4°C

Handling Guidelines:

• Upon receipt, centrifuge the antibody briefly to collect all material at the bottom of the tube

• Divide into small working aliquots to minimize freeze-thaw cycles

• Mix gently by inversion rather than vortexing to preserve antibody integrity

While specific shelf life may vary between manufacturers, antibodies in this storage buffer typically remain stable for at least 12 months when stored properly at -20°C. Always refer to the product datasheet for the specific storage recommendations and expiration information provided by the manufacturer.

The liquid form of the antibody (as opposed to lyophilized) eliminates the need for reconstitution, making it convenient for immediate use while maintaining stability through the inclusion of glycerol and preservatives in the storage buffer .

How can Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody be utilized in stem cell research?

The Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody offers valuable insights into stem cell biology, particularly in understanding the molecular mechanisms governing pluripotency and differentiation:

Monitoring Pluripotency Networks:
Research has revealed that EPHA2 is highly expressed in embryonic stem cells (ESCs) and plays a significant role in maintaining pluripotency . Using the Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody, researchers can track receptor activation status in pluripotent cells and correlate it with the expression of pluripotency factors such as NANOG and KLF4. EFNA1-expressing EPHA2-positive mESCs display increased EPHA2 tyrosine phosphorylation, which correlates with elevated expression of pluripotency markers .

Studying Differentiation Dynamics:
During ESC differentiation, significant changes occur in the phosphorylation status of EPHA2. The antibody can be used to monitor this phosphorylation switch temporally as cells transition from pluripotency to a differentiated state. This approach has revealed that FGF4 signaling triggers inhibitory serine/threonine phosphorylation of EPHA2, which contributes to the exit from pluripotency .

Embryonic Development Studies:
A-type EPH receptors are expressed in the pluripotent compartment of both human and mouse embryos, while surrounding lineage-specified trophectoderm expresses EFNA ligands . This segregated expression pattern suggests a role for EPH-EFN signaling in coordinating cell fate decisions with tissue compartmentalization. The antibody can help researchers visualize and quantify phosphorylation patterns in different embryonic compartments.

Functional Studies:
By combining this antibody with genetic approaches (such as EPHA2 knockout or knock-in models), researchers can perform mechanistic studies to determine how phosphorylation at Y588/596 affects pluripotency maintenance and differentiation. For example, researchers have shown that EPHA2 knockout mESCs display reduced KLF4 and increased DNMT3B expression during differentiation compared to control cells, and this effect can be rescued by reintroducing EPHA2 .

The table below summarizes key findings from stem cell research using Phospho-EPHA2/3/4 antibodies:

This antibody thus serves as a critical tool for understanding the molecular switches that govern stem cell fate decisions.

What role does EPHA2 phosphorylation play in the transition from pluripotency to differentiation?

EPHA2 phosphorylation serves as a critical molecular switch that regulates the balance between pluripotency maintenance and differentiation initiation in embryonic stem cells:

Pluripotency Maintenance Mechanism:
In pluripotent ESCs, EPHA2 is highly expressed and primarily phosphorylated at tyrosine residues (including Y588/596) in response to ephrin ligand binding. This tyrosine phosphorylation activates EPHA2 signaling that supports expression of pluripotency factors like NANOG and KLF4 . Importantly, activated EPHA2 antagonizes ERK1/2 signaling, which is known to promote differentiation. This creates a signaling circuit where EPHA2 activity helps maintain the pluripotent state.

FGF4-Mediated Bimodal Switch During Differentiation:
During differentiation, FGF4 initiates a sophisticated bimodal strategy to disable EPHA2 function:

• Post-translational mechanism: FGF4 activates ERK1/2, which signals through RSK to drive inhibitory serine/threonine phosphorylation of EPHA2. This modification blunts the receptor's response to ephrin ligands, reducing its ability to maintain pluripotency .

• Transcriptional mechanism: Simultaneously, FGF4-ERK1/2 signaling disrupts the core pluripotency transcriptional circuit required for Epha2 gene expression, leading to reduced EPHA2 protein levels .

This dual inhibitory mechanism creates a robust feed-forward loop that reinforces the transition from pluripotency toward differentiation. As FGF4 signaling increases, it inhibits EPHA2 through S/T phosphorylation, which permits increased ERK1/2 signaling, which further suppresses EPHA2 expression and activity.

Coordinated Tissue Patterning:
The differentiation process is also accompanied by transcriptional induction of ephrin ligands, creating a system where segregated EPH-EFN expression may coordinate cell fate decisions with compartmentalization during early embryonic development . The pluripotent compartment of both human and mouse embryos expresses A-type EPH receptors, while the surrounding trophectoderm (the first lineage-specified tissue) is enriched for EFN ligands.

By using the Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody to monitor tyrosine phosphorylation and other phospho-specific antibodies to track serine phosphorylation, researchers can observe this molecular switch in action and understand how changes in phosphorylation status contribute to cell fate decisions during early development.

How can researchers effectively study the dual phosphorylation mechanisms (tyrosine vs. serine) of EPHA2?

Studying the dual phosphorylation mechanisms of EPHA2 requires sophisticated experimental approaches that can distinguish between tyrosine and serine/threonine phosphorylation events:

Complementary Phospho-specific Antibodies:
Researchers should employ multiple phospho-specific antibodies to track different phosphorylation events:

• Phospho-EPHA2/EPHA3/EPHA4 (Y588/596) Antibody to detect activating tyrosine phosphorylation

• Phospho-EPHA2 (S898) antibody to monitor inhibitory serine phosphorylation induced by FGF4