The G protein-coupled receptor (GPCR) superfamily represents the largest class of membrane proteins in the human genome, mediating a vast array of signal transduction pathways essential for physiological function. Consequently, GPCR drug discovery remains a dominant focus of the pharmaceutical industry, with approximately 35% of approved drugs targeting these receptors. While small molecules have traditionally dominated this landscape, there is a growing paradigm shift toward anti-GPCR monoclonal antibody therapeutics. Antibodies offer superior specificity, extended half-life, and the unique ability to modulate receptor function through varied mechanisms, including biased agonism and allosteric regulation. However, the discovery of functional antibodies against these multi-pass membrane protein targets is notoriously challenging due to their low natural abundance, structural instability outside the lipid bilayer, and limited solvent-exposed surface area.
Creative Biolabs overcomes these hurdles with a comprehensive GPCR antibody discovery service powered by advanced phage display technology. As a key part of our Phage Display for Challenging Target Discovery platform, we integrate innovative antigen presentation strategies—such as Nanodiscs and Virus-Like Particles (VLPs)—with our diverse GPCR phage display library resources to successfully isolate high-affinity binders that act as agonists, antagonists, or inverse agonists.
Developing antibodies against membrane receptors presents unique obstacles that traditional hybridoma methods often fail to address:
We provide a modular service tailored to the specific nature of your receptor, whether it is a well-characterized Class A GPCR or a challenging receptor.
Success begins with the antigen. We specialize in stabilized GPCR screening formats. We express receptors in mammalian or insect cells and solubilize them using next-generation detergents, Amphipols, or incorporate them into Nanodiscs and VLPs to maintain native conformation and ligand-binding capability.
We utilize both immune libraries (from llamas, camels, or transgenic mice) and our proprietary synthetic human antibody libraries. Our panning strategies are designed to enrich for specific conformational states (active vs. inactive), enabling the isolation of conformation-selective binders.
We go beyond simple binding. Our platform integrates high-throughput functional assays, including cAMP accumulation and Calcium flux (FLIPR) recruitment assays to characterize the pharmacological profile of identified hits early in the discovery process.
Once a lead candidates is identified, we offer affinity maturation and format conversion services. We can reformat scFv or VHH binders into full-length IgG, bispecific antibodies, or antibody-drug conjugates (ADCs) tailored for therapeutic development.
Our streamlined process ensures the delivery of validated, functional leads.
We evaluate the target receptor sequence and design optimal expression constructs. Receptors are expressed and purified or constituted into lipid-bilayer mimetics. Quality is verified via ligand binding assays to ensure functional integrity.
We perform 3-4 rounds of bio-panning. We employ alternating selection strategies (e.g., whole-cell panning followed by VLP panning) to minimize background binding to lipid components and maximize specificity for the receptor.
Individual clones are screened by ELISA and FACS. Confirmed binders are then subjected to functional cell-based assays to determine their activity (agonist/antagonist) and mechanism of action.
The anti-GPCR antibodies generated through our platform facilitate a wide range of advanced research applications, serving as critical tools for structural determination and mechanistic studies.
GPCRs are notoriously difficult to crystallize due to their flexibility. Our high-affinity antibodies (especially VHHs and Fabs) serve as crystallization chaperones. They stabilize specific receptor conformations (active or inactive) and increase the hydrophilic surface area, significantly facilitating high-resolution structure determination via X-ray crystallography or Cryo-EM.
Functional antibodies act as precise molecular probes to dissect signaling pathways in vitro. Researchers use them to distinguish between G-protein dependent signaling and biased signaling pathways, or to map allosteric modulation sites that are distinct from the orthosteric ligand-binding pocket.
Antibodies recognizing extracellular epitopes allow researchers to track endogenous receptor expression, internalization, recycling, and degradation dynamics in live or fixed cells. This approach avoids the need for artificial fusion tags (like GFP) that might alter native receptor pharmacology.
Addressing the challenges in discovering functional antibodies against GPCRs, a novel function-based high-throughput screening paradigm has been developed. Unlike conventional binding-focused assays that often yield non-functional binders, this method synergizes GPI-anchored antibody cell display with a downstream GPCR signaling reporter assay to directly select for bioactivity. The platform's capability to isolate potent inhibitors is highlighted in a validation study targeting the human apelin receptor (APJ). As depicted in Figure 1, an iterative flow cytometry sorting strategy was utilized to progressively enrich cell populations displaying antagonistic properties. Following three rounds of selection, the process successfully amplified the population of functional clones, with clonal analysis revealing a high frequency of potent antagonists. Notably, the data established a significant correlation between the functional inhibition observed in cell-displayed clones and the IC50 values of the purified soluble sdAbs. These results confirm the method's efficiency in bridging antibody genotype with functional phenotype, offering a superior alternative to traditional screening methods for complex membrane targets.
Fig.1 Enrichment of GPCR antibody antagonists from a combinatorial library using function-based high-throughput cell sorting.1
Q: How do you ensure the GPCR retains its native structure during panning?
Q: Can you generate antibodies against a specific GPCR conformation?
A: Yes. By performing panning in the presence of specific agonists or antagonists, or by using mutant receptors stabilized in a particular state, we can bias the selection toward antibodies that recognize the active or inactive conformation.
Q: What is the typical timeline for a GPCR antibody discovery project?
A: A standard project typically ranges from 12 to 16 weeks. This includes antigen preparation (expression and purification/stabilization), library construction or selection, panning, and primary screening. Timelines may vary depending on the complexity of the target and the specific deliverables required.
Q: Can you screen for antibodies that cross-react with orthologs (e.g., Human and Mouse)?
A: Yes. We can design a panning strategy that alternates between human and mouse receptor orthologs to enrich for cross-reactive binders. This is particularly valuable for validating findings in animal models during downstream research.
Q: My GPCR target is toxic to host cells. Can you still generate antibodies?
A: Yes. For toxic GPCRs, we utilize specialized inducible expression systems, cell-free expression platforms, or proteoliposomes to bypass host toxicity issues while maintaining the receptor in a functional format for screening.
Q: What are the standard deliverables for this service?
A: Upon project completion, we deliver the full sequences of the identified binders, a detailed report including ELISA/FACS validation data, and the physical clones (plasmids or glycerol stocks). Purified antibody proteins (mg to gram scale) can also be provided upon request.
"We struggled with a Class B GPCR for months. Creative Biolabs suggested using Nanodiscs for panning. It was a game changer. The binders we got recognize the native structure perfectly. Great communication throughout the project."
"I was worried about getting antibodies that bind but don't do anything. Their team used a functional screening method that actually worked. We found a potent agonist candidate in just 14 weeks. The report data was super clear."
"Our lab needed VHHs to help crystallize a receptor. The library they used must be high quality because we got very stable clones. The team understood exactly what we needed for structural biology. Highly recommend their service."
"Professional service. We sent them the target sequence, and they handled everything from antigen production to FACS validation. The turnaround was faster than expected, and the antibody affinity was in the nanomolar range."
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Please kindly note that our services can only be used to support research purposes (Not for clinical use).
Creative Biolabs is a globally recognized phage company. Creative Biolabs is committed to providing researchers with the most reliable service and the most competitive price.
