Membrane protein ligand binding assays
CALIXAR offers the access to cutting-edge technologies and to characterize ligand interaction with any membrane protein targets. Our ligand binding assays services help scientists and researchers who want to obtain accurate ligand binding parameters, compare several ligands in term of binding properties or just identify a specific interaction of their ligands with the membrane target of interest.
MicroScale Thermophoresis with Isothermal Spectral Shift
With the first Monolith X (Nanotemper) installed in France, CALIXAR increases its analytical capabilities in ligand binding to any type of membrane protein. Scientists and researchers are assured of having access to the latest technologies to characterize membrane targets.
Thanks to the MicroScale Thermophoresis (MST) combined with isothermal spectral shift detection, CALIXAR offers to determine in solution interactions of membrane proteins with unlabeled ligands. Binding measurements can be performed using purified membrane targets or proteins in complex environment such as cell membrane.

Detection :
Dynamic range: 1nm to mM
Detected molecule range: 101 – 107 Daltons
Samples per run: Up to 24
Unlike conventional approaches that would alter the native structure of membrane proteins, CALIXAR’s approach allows the conservation of the functional and structural integrities of the targets/ antigens. This has a significantly positive impact on the quality of the protein and on the success of proteomics, drug discovery applications (including vaccine, small molecules, and antibody development).
- Avoid problems of low yield, toxicity, aggregates.
- Identify the best conditions to give the best chances to the projects.
CALIXAR is unique on the market and at the vanguard of Membrane protein extraction/solubilization, purification and characterization services. Our technological platform allows to maximize the chances of success of drug discovery projects related to highly challenging and druggable targets.
A2AR ligand binding assays using microscale thermophoresis (MST) combined with isothermal spectral shift.
Ligand binding assays were performed on full-length wild-type A2A adenosine receptor either in cell membrane fractions (A) or purified in solution (B) and with CGS21680 agonist or ZM241385 inverse agonist using a Monolith X (Nanotemper) combining microscale thermophoresis with isothermal spectral shift detection.



Gain access to CALIXAR's Membrane Protein Expression Technology.
All of our clients gain access to our proprietary technologies and expertise (8 patent families, more than 28 publications).
CALIXAR discovers and develops new procedures to express and isolate full-length membrane therapeutic targets (GPCRs, ion channels, receptors, transporters, and viral targets) with the highest purity and functionality levels.
The CALIXAR® platform uses patented technology only available for our clients under specific agreements (license, co-development, and service).
You can leverage CALIXAR’s proprietary technology as well as other best-in-class membrane protein technology that is not found anywhere else on the market. Get access to our proprietary technology and know-how (7 patent families, 15 publications).
This combined approach guarantees that our Membrane Proteins are expressed in the best conditions with optimized yields and expression rates. No contaminants or aggregates are found in our production.
Radioligand Binding Assay
CALIXAR offers ligand binding characterization to any membrane protein using radiolabeled [3H]-ligand.
The well-established and robust radioactive method enables high-sensitive detection of membrane protein / ligand interactions. Binding measurements can be performed using purified membrane targets or proteins in complex environment such as cell membrane.
Filtermat-96 Cell Harvester with MicroBeta2 Microplate Counters.
Simple simultaneous analysis of samples from 96- well microplates for filtration-based receptor binding assays. Radiometric 3H-labeled ligands detection is ensured with high efficiency and extremely low background.


A2AR radioligand binding assays.
Saturation radioligand binding assays were performed on purified full-length wild-type A2A adenosine receptor with [3H]-CGS21680 agonist (A) or [3H]-ZM241385 inverse agonist (B).


Fluorescence Polarization
CALIXAR identifies challenging protein-ligand interactions by using Fluorescence Polarization.
Fluorescence polarization is a method to measure protein-ligand interactions by detection the changes of small molecule rotation. When a fluorescently labeled small ligand is bound to a bigger protein the emitted light is polarized due to the slow movement of the complex.


Purified Multidrug Efflux Pump subunit AcrB
Ligand binding assay was performed on purified full-length wild-type AcrB with Rhodamine G6 ligand using fluorescence polarization.
G6Kd: 6 µM

Purified Voltage-Gated Sodium Channel (Nav1.7)
Ligand binding assay was performed on purified full-length wild-type Nav1.7 ion channel with protoxin-II (Cy5-ProTx-II) using fluorescence polarization.


Get access to CALIXAR's Membrane Protein Assays Technology
CALIXAR identifies challenging protein-ligand interactions by using Fluorescence Polarization.
The CALIXAR® platform uses patented technology only possible for clients under explicit agreements (license, co-development, and services).
You can leverage CALIXAR’s proprietary technology as well as other leading-in-class membrane protein technology that is not found anyplace else on the market.
Gain access to our specific expertise with a strong track record and several types of membrane proteins. We are continuously integrating best-of-the-art membrane protein characterization technology for our clients’ projects. Our clients have access to all assays needed for their projects, all on one platform.
- Save time and money by using our unique assay services all in the same place.
- Possibility to develop customized assays (transferable to our clients).
- Possibility to validate customers’ hits/leads and the quality of the proteins produced.