Background
KACTUS offers a specialized range of VLP (virus-like particle) and Nanodisc transmembrane proteins, designed for accurate representation of multi-pass transmembrane proteins in their native conformation. These full-length proteins are produced using detergent-free extraction methods, ensuring the preservation of structural integrity and biological activity. To support a wide range of applications, including ELISA, flow cytometry, and SPR, our transmembrane proteins can be biotinylated or fluorescently labeled, offering flexibility for research needs. Additionally, we test our VLPs and Nanodiscs for bioactivity through SPR, ELISA, and flow cytometry, ensuring batch consistency and reliability. KACTUS’ VLP and Nanodisc products are valuable tools for studies in antibody discovery, antibody screening, analytical method development, and immunization.
Technology Platforms
Virus-Like Particle (VLP)
Mammalian-expressed transmembrane proteins displayed on VLPs for native conformation and boosted immunogenicity
Nanodisc
Transmembrane proteins expressed on membrane-like structures composed of phospholipids and copolymers
Virus-like Particles (VLPs)
Virus-like particles (VLPs) are small nanoparticles composed of the structural proteins of a virus, specifically the shell or capsid proteins. These proteins self-assemble into virus-like structures, mimicking the organization and morphology of the actual virus. However, VLPs are devoid of the viral infectious genomes, rendering them non-infectious and relatively safe for use in various applications, including vaccine development and gene therapy.
Mechanism of expression for VLP-displayed antigens.
Why use VLP-displayed antigens?
Virus-Like Particles (VLPs) are good at boosting the immune response. This makes them useful for immunization, especially with antigen targets that are usually present in low amounts or don’t trigger a strong immune reaction by themselves. They also allow for soluble expression of multipass transmembrane proteins in their natural configuration.
Applications
→ Blood sample determination: ELISA
→ In vivo pharmacokinetic analysis
→ Antibody Immunization, Screening, Functional Characterization
→ CMC method development
→ Affinity determination: ELISA, SPR
Features
→ Site-Specific Biotinylation
→ VLP framework optimized to each antigen
→ Proven biological activity via ELISA and SPR
→ Mammalian cell expression system for natural folding and glycosylation
→ Boosted immunogenicity for antibody drug discovery
Product Validation Data
Claudin 18.2 VLP
In 2018, KACTUS became the first company globally to express full-length wild-type Claudin 18.2, a multi-transmembrane protein with significant implications for gastric and esophageal adenocarcinomas. Despite its potential, technical challenges in generating high-quality Claudin 18.2 antigen have previously hindered antibody isolation and production quality control. Leveraging our SAMS™ protein engineering and expression platform, we have successfully produced full-length Claudin 18.2 antigens on VLPs. Our robust product performance testing demonstrates the functional integrity and bioactivity of our VLP expression platform.
Figure 1. This graph illustrates the intensity distribution of Claudin 18.2 VLPs as measured by dynamic light scattering (DLS). The peak centered at approximately 150 nm indicates a homogeneous population of VLPs, reflecting the consistent size and quality of the particles.
Figure 2. The chromatogram shows the high-performance liquid chromatography (HPLC) profile of Claudin 18.2 VLPs, with a prominent peak observed at 4.909 minutes, indicating the retention time of the Claudin 18.2 protein. The sharp and well-defined peak suggests a high purity and consistency of the VLP preparation.
Figure 3. ELISA assay shows the binding activity of Claudin 18.2 VLPs to anti-Claudin 18.2 antibodies across three different production batches. The consistent curves for Batches 1, 2, and 3 highlight the reproducibility and stability of the VLP preparations. The half-maximal effective concentration (EC50) is determined to be 0.1 nM, indicating high affinity and robust interaction between Claudin 18.2 VLPs and the specific antibodies.
Figure 4. Biolayer Interferometry (BLI) day demonstrates the binding kinetics of Claudin 18.2 VLPs to streptavidin-labeled probes. The analysis reveals a high binding affinity with a dissociation constant (KD) of approximately 5.73E-10 M, indicating strong and stable interaction.
Figure 5. Flow cytometry data demonstrates the binding specificity and quantification of Claudin 18.2 displayed on VLPs. The top panels show the results from HEK293 control cells, while the bottom panels show the results from anti-Cld18.2 CAR-expressing HEK293 cells. The presence of Cld18.2 VLPs results in a significant shift in the fluorescence signal in anti-Cld18.2 CAR-expressing cells, indicating successful detection and quantification of Cld18.2 on VLPs. This validates the high-quality expression and bioactivity of the Claudin 18.2 VLPs.
Figure 6. SPR data showing the binding interactions of Biotinylated Claudin 18.2 VLPs with streptavidin immobilized on a CM5 chip. Results show a dissociation constant (KD) of 1.638E-11 M. This indicates a very strong and stable binding affinity of the Claudin 18.2 VLP.
Nanodiscs
Nanodiscs are membrane-like structures composed of phospholipids and membrane scaffold molecules, which are typically synthetic copolymers or membrane scaffold proteins. We use a proprietary amphipathic copolymer to enable membrane protein stabilization & solubilization without the use of detergents.
Schematic diagram of nanodisc displaying a multi-transmembrane protein
Why use nanodisc-displayed antigens?
Using Nanodisc technology to display multitransmembrane proteins not only better maintains their natural conformation but also addresses the issue of soluble preparation of these proteins. Moreover, because nanodiscs can be extracted without detergents, they offer a superior alternative for multitransmembrane proteins that are sensitive to maintaining activity with detergents.
Applications
→ Yeast display screening
→ In vitro functional assays
→ CAR expression testing
→ PK/PD Studies
→ Analytical Tests, ELISA, SPR, BLI
Features
→ Native structure and conformation
→ Detergent free extraction for reliable performance
→ Good water solubility
→ Proven biological activity via ELISA and SPR
→ Mammalian cell expression system for natural folding and glycosylation
Product Validation Data
GPRC5D Nanodisc
GPRC5D is an important multitransmembrane protein with significant therapeutic and research potential. To ensure the most accurate representation of its natural conformation and activity, we've developed a GPRC5D Nanodisc with detergent-free extraction. This innovative approach not only maintains the native structure of GPRC5D but also overcomes the challenges associated with the soluble preparation of multi-transmembrane proteins. We've performed extensive product quality testing to demonstrate the efficacy and quality of our Nanodisc-based antigens.
Additionally, to further support the development of antibody drugs (such as bispecific antibodies), we've developed biotinylated Nanodisc-displayed multitransmembrane proteins. These proteins exhibit high binding activity and can be applied to various research stages, including ELISA method development and pharmacokinetic analysis.
Figure 7. Human GPRC5D Nanodisc with His Tag was immobilized at 2 µg/ml (100 µl/well) on the plate. The dose-response curve for the Anti-GPRC5D Antibody with hFc Tag was generated, with an EC50 of 4.9 ng/ml as determined by ELISA.
Figure 8. Human CD3E&CD3D, with a His Tag, was immobilized on the plate at a concentration of 2 ÎĽg/mL (100 ÎĽL/well). Serial dilutions of the Anti-Human CD3Ă—GPRC5D bispecific antibody, with an hFc Tag, were then added, followed by the addition of biotinylated Human GPRC5D Nanodisc, with a His Tag, at 5 ÎĽg/mL. Detection was performed using HRP-conjugated streptavidin, and the EC50 was determined to be 0.28 ÎĽg/mL by ELISA.
Figure 9. Biotinylated Human GPRC5D Nanodisc, with a His Tag, was loaded onto an SA-Biosensor. This setup was used to determine the binding affinity to the Anti-GPRC5D Antibody, which was measured to be 1.16 nM using a BLI assay.
Figure 10. Human GPRC5D Nanodisc with His Tag was captured on a CM5 Chip via an anti-His antibody. It was found to bind the Anti-GPRC5D Antibody with an affinity constant of 1.47 nM, as determined by SPR assay (Biacore T200).
Available Products
KACTUS VLP-Displayed Antigens FAQs
KACTUS can provide VLPs in liquid or lyophilized form. Lyophilized format allows for the use of a custom buffer or adjuvant during screening or immunization as desired. It also ensures stability of the VLPs for use in a variety of settings, such as for screening or immunization. Our lyophilization team tests our catalog products for activity after lyophilization, to ensure you are still receiving a bioactive protein.
Generally, VLPs range in size from approximately 20 to 200 nanometers (nm). Their smaller size lets engineered VLPs focus the immune response on specific surface antigens, more so than cell-based immunization.
Our VLPs are produced with high quality standards. Although it is difficult to determine the exact number of copies of the antigen displayed on the surface of the VLP, we take steps to validate each batch of VLPs to assure the displayed protein will have consistency across batches.
To guarantee VLP quality, KACTUS follows a strict validation process involving various analytical techniques for each batch. This process includes techniques such as size exclusion chromatography, ELISA, and SPR.
Browse the catalog and order directly online via credit card or email us at orders@kactusbio.us to place an order via PO.
Contact us here to request a custom VLP protein.
Our catalog products have a lead time of 2 days to 2 weeks. Custom orders have a turnaround time of 6-8 weeks. Contact us for more information.
Contact us to request more information or set up a meeting with one of our team members.
Customize your VLP or Nanodisc
Our team can produce custom multi-pass transmembrane proteins displayed on VLPs or Nanodiscs with your specific tags, labels, biotinylation, etc. Learn more about our custom VLP & Nanodisc services
Custom VLP & Nanodisc Services
About KACTUS
SAMS™ Technology Platform
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VLP & Nanodisc Displayed Transmembrane Proteins | KACTUS