GPCR Immunogen Preparation Service

Based on our world-leading Magic™ Membrane Protein Production Platform, scientists from Creative Biolabs now provide professional GPCR immunogen preparation service.

G protein-coupled receptors (GPCRs) constitute the largest membrane receptor family with over 800 members. Given their high relevance to diverse diseases, GPCRs act as excellent therapeutic targets of over 40% modern drugs, especially therapeutic antibodies. However, one of the major difficulties for anti-GPCR antibody development lies in the appropriate preparation immunogen, due to their complicated structure and low abundance. After years of devotion, scientists in Creative Biolabs have established a full range of methodologies for obtaining native, functional GPCR proteins that can serve as great immunogens in vivo. We provide flexible options, e.g. detergent micelles, nanodiscs, liposomes, polymers, over-expressing cells, lipoparticles, etc. (as listed below), which from you can always find the best fit for your particular target.

Figure 1 Schematic of GPCR as immunogen or antigen. (Jo M and Jung ST, 2016)

GPCR reconstitution in liposomes, namely proteoliposome, is one of the most conventional immunogen choices. The lipid bilayer can help to stabilize membrane proteins in correct status with active functionalities. High-purity proteoliposomes can guarantee very efficient antibody secretion in vivo, thus being a good choice for GPCR immunogen use. Proteoliposomes can be prepared from either cell-based expression or cell-free expression systems. With the aid of our Lipid Screening Platform, we will perform comprehensive condition screening to find the optimal lipid components.
GPCR reconstitution in nanodiscs offers a nearly natural environment with transmembrane regions inserted into a phospholipid bilayer, which is stabilized by membrane scaffold protein (MSP). It offers a convenient reconstitution format not only highly mimics the natural plasma membrane, but also very flexible in terms of size and composition. Compared to proteoliposomes, nanodiscs are more stable, homogenous and controllable in terms of size and composition. Both cell-based expression and cell-free expression can be used for nanodisc production.
GPCR incorporation in polymers is a new approach for GPCR solubilization. Two kinds of amphipathic polymers, amphipols and styrene-maleic acid copolymer lipid particles (SMALPs), do not disrupt the native lipid environment around the target protein; instead, they can directly isolate and solubilize membrane-lipid complex. It offers a detergent-free solution to stabilize GPCRs with maximally preserved structure and activities.
GPCR over-expressing cell lines can also be directly used for immunization & antibody selection. Unlike recombinant approaches, GPCRs in cellular format have minimum risks in regard to native structure/functions/modification. Several key points for whole cell immunogen include sufficient expression levels, appropriate immunization process, and adequate antibody screening. Currently, we provide over 100 GPCR overexpressing cell lines (HEK293/CHO/U2OS background). Customized stable cell line can also be constructed upon request.
GPCR-displaying lipoparticles are formed by co-transfecting cells with vectors encoding target GPCRs and viral core protein (e.g. Gag). After budding off from host cells, the viral core will spontaneously capture plasma membrane fractions enriched with the target protein, aka lipoparticles. The lipoparticles displaying the protein of interest can then be used for a variety of applications, including immunization, antibody screening, drug delivery, assay development, etc.
Peptide surrogate antigen: Peptide derived from extracellular/intracellular loops is also a commonly used approach for GPCR antibody development, particularly when there are large/functionally relevant extracellular/intracellular loops. Hence, surrogate peptides, if carefully designed and characterized, can serve as good immunogens in many cases.
GPCRs incorporated in exosomes: Exosomes are secreted membrane nanovesicles (diameter 50-100 nm) that form within late endosomal compartments by the fusion of multivesicular bodies with the plasma membrane. Membrane proteins incorporated in exosomes, especially secreted from dendritic cells, cause strong immune responses even without additional adjuvant. Also, exosomes provide a native membrane environment and have stable storage property.

Creative Biolabs is dedicated to tailoring one-stop membrane protein service to support custom programs from immunogen preparation, antibody discovery, to antibody scale-up production and purification. Please feel free to contact us for more details.

Reference

Jo M and Jung S T. (2016). Engineering therapeutic antibodies targeting G-protein-coupled receptors. Experimental & Molecular Medicine, 48, e207.

All listed services and products are For Research Use Only. Do Not use in any diagnostic or therapeutic applications.

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