Recombinant Human CDH4 Protein: Handling & Application Protocol

Recombinant Human CDH4 Protein is a purified, bioactive form of R-cadherin designed to support cell adhesion studies, homophilic binding assays, and cadherin-mediated signaling research in a reproducible laboratory setting.

Protein Name

Recombinant Human CDH4 (R-cadherin)

SKU

rp365838

Protein Family

Classical cadherin (Type II cadherin superfamily)

Primary Applications

Cell adhesion assays, homophilic binding studies, functional in vitro assays

Recommended Storage

-80 °C for long-term; avoid repeated freeze-thaw cycles

Calcium Dependency

CDH4 adhesive function requires extracellular calcium ions (Ca²⁺)

Background: CDH4 Biology and Research Significance

CDH4 (Cadherin-4), also known as R-cadherin (retinal cadherin), is a classical type II transmembrane glycoprotein belonging to the cadherin superfamily. It mediates calcium-dependent, homophilic cell–cell adhesion and plays critical roles in neural tissue development, retinal patterning, and somitogenesis. CDH4 engages in cis- and trans-dimerization at the cell surface, and its extracellular domain interacts with partner cadherins in a Ca²⁺-dependent manner.

In research contexts, CDH4 has been implicated in neuronal circuit formation, tumor invasion, and epithelial–mesenchymal transition (EMT). Recombinant Human CDH4 Protein enables investigators to study these processes in defined, cell-free systems or to coat surfaces for cell adhesion assays, making it a versatile reagent for both basic and translational research programs.

Reconstitution and Storage Guidelines

Reconstitution: Briefly centrifuge the vial before opening to collect lyophilized material at the bottom. Reconstitute the protein in sterile, ultrapure water or an appropriate physiological buffer (e.g., PBS, pH 7.4) to the desired working concentration. Allow the solution to stand at room temperature for 5–10 minutes and mix gently by pipetting; avoid vortexing, which may cause protein denaturation or aggregation.

Working buffer consideration: Because CDH4 function is calcium-dependent, supplement buffers used in functional assays with Ca²⁺ (typically 1–2 mM CaCl₂) to maintain adhesive activity. EDTA or EGTA-containing buffers will chelate calcium and abolish cadherin-mediated adhesion.

Storage: Store the lyophilized protein at –20 °C or –80 °C. After reconstitution, prepare single-use aliquots to avoid repeated freeze-thaw cycles, which degrade protein activity. Aliquots may be stored at –80 °C for up to 3 months. For short-term use (≤1 week), store reconstituted protein at 4 °C with a carrier protein (e.g., 0.1% BSA) to minimize surface adsorption losses.

Note: Specific concentration, formulation details, and recommended working ranges should be confirmed from the Certificate of Analysis (CoA) supplied with each lot (rp365838).

Application Protocol: Cell Adhesion and Homophilic Binding Assay

Materials required: Recombinant Human CDH4 Protein (rp365838), 96-well tissue-culture plate, coating buffer (PBS pH 7.4 with 1–2 mM CaCl₂), blocking buffer (1% BSA in PBS), appropriate cells expressing CDH4 or a complementary cadherin, and cell counting reagents.

Step 1 – Plate coating: Dilute CDH4 protein to the desired coating concentration (empirically determined; typically 1–10 µg/mL as a starting range) in coating buffer. Add 100 µL per well of a 96-well plate. Incubate overnight at 4 °C or for 2 hours at 37 °C.

Step 2 – Blocking: Aspirate unbound protein. Add 200 µL blocking buffer per well and incubate for 1 hour at room temperature to prevent non-specific cell attachment.

Step 3 – Cell seeding: Aspirate blocking buffer. Add cell suspension (5 × 10⁴ to 1 × 10⁵ cells per well in serum-free medium supplemented with 1–2 mM CaCl₂). Incubate for 30–60 minutes at 37 °C, 5% CO₂.

Step 4 – Wash and quantify: Gently wash wells 2–3 times with PBS to remove non-adherent cells. Fix adherent cells and quantify by crystal violet staining, fluorescence, or cell viability assay. Include a Ca²⁺-chelated (EGTA) negative control and an uncoated BSA-only plate as baseline adhesion control.

Step 5 – Data analysis: Express adhesion as percentage of input cells or as absorbance relative to control wells. Statistical comparisons should include biological triplicates at minimum.

Quality Control and Troubleshooting

Quality control: Each lot of Recombinant Human CDH4 Protein (rp365838) should be accompanied by a Certificate of Analysis documenting purity (typically assessed by SDS-PAGE), biological activity, endotoxin level, and sterility where applicable. Confirm protein integrity upon receipt by running an aliquot on a reduced SDS-PAGE gel and comparing the observed molecular weight band to the expected value for CDH4 (the mature extracellular domain construct). Endotoxin levels should be low (verify on CoA) to prevent confounding inflammatory responses in cell-based assays.

Troubleshooting guide:

• Low or absent cell adhesion: Verify Ca²⁺ is present in all assay buffers; confirm protein was not exposed to EDTA/EGTA. Check that the coating step was performed correctly and that protein is not denatured (re-run SDS-PAGE).
• High background (non-specific adhesion): Increase blocking time or BSA concentration. Optimize wash stringency. Use a non-adhesive polymer-coated plate for negative control.
• Protein aggregation: Ensure reconstitution was performed gently without vortexing. Centrifuge reconstituted stock at 10,000 × g for 5 minutes at 4 °C to pellet aggregates before use.
• Activity loss over time: Minimize freeze-thaw cycles; aliquot before freezing. Add BSA carrier (0.1%) for dilute working stocks.

Safety, Regulatory, and Ordering Information

Safety: Recombinant Human CDH4 Protein is a research-use-only (RUO) reagent and is not intended for diagnostic, therapeutic, or any clinical use. Handle all recombinant proteins using standard laboratory safety practices: wear gloves, lab coat, and eye protection. Consult the Safety Data Sheet (SDS) for detailed hazard information specific to this product.

Regulatory status: This product is manufactured and supplied for in vitro research use only and has not been evaluated for use in humans or animals as a drug, food, or medical device.

Ordering: Recombinant Human CDH4 Protein is available from Aladdin Scientific under SKU rp365838. Contact your regional Aladdin Scientific representative or visit the product page for pricing, available quantities, and current stock status. For bulk or custom requests, contact technical support.

Technical support: For application-specific questions, reconstitution guidance, or troubleshooting assistance, contact Aladdin Scientific technical support, referencing product SKU rp365838 and your lot number from the CoA.

Frequently asked questions

What buffer should I use to reconstitute Recombinant Human CDH4 Protein?

Reconstitute CDH4 protein in sterile ultrapure water or PBS (pH 7.4). For functional assays requiring adhesive activity, supplement all buffers with 1–2 mM CaCl₂, as CDH4-mediated adhesion is strictly calcium-dependent. Avoid any EDTA- or EGTA-containing buffers, which chelate calcium and abolish cadherin activity.

How should Recombinant Human CDH4 Protein be stored to maintain activity?

Store lyophilized protein at –20 °C or –80 °C. After reconstitution, aliquot into single-use volumes immediately and store at –80 °C for up to 3 months. Avoid repeated freeze-thaw cycles, which progressively degrade protein activity. For working stocks used within one week, store at 4 °C with 0.1% BSA as a carrier.

What are the recommended applications for Recombinant Human CDH4 Protein?

Recombinant Human CDH4 Protein is suited for cell adhesion assays (plate-coating format), homophilic cadherin binding studies, surface plasmon resonance (SPR) or ELISA-based binding kinetics, and functional investigations of cadherin-mediated signaling in neural or epithelial model systems. It is for in vitro research use only.

How do I troubleshoot low cell adhesion in my CDH4 adhesion assay?

First, confirm that Ca²⁺ (1–2 mM CaCl₂) is present in all assay buffers and that no chelating agents such as EDTA or EGTA have been introduced. Verify the coating concentration and incubation conditions, and confirm protein integrity via SDS-PAGE. If aggregation is suspected, centrifuge the reconstituted protein at 10,000 × g for 5 minutes at 4 °C before use.

Is Recombinant Human CDH4 Protein (rp365838) suitable for in vivo use?

No. Recombinant Human CDH4 Protein (rp365838) is designated for research use only (RUO) and has not been tested or approved for in vivo, diagnostic, or therapeutic applications. It must not be administered to humans or animals.

References

1. Shimoyama Y, Tsujimoto G, Kitajima M, Natori M. Identification of three human type-II classic cadherins and frequent heterophilic interactions between different subclasses of type-II classic cadherins. Biochemical Journal. 2000;349(1):159–167. doi:10.1042/bj3490159
2. Takeichi M. Cadherin cell adhesion receptors as a morphogenetic regulator. Science. 1991;251(5000):1451–1455. doi:10.1126/science.2006419
3. Wheelock MJ, Johnson KR. Cadherin-mediated cellular signaling. Current Opinion in Cell Biology. 2003;15(5):509–514. doi:10.1016/S0955-0674(03)00101-7

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.