Functional Assays

Functional Assays

GTP binding is a method used to study distribution and functional activation of seven transmembrane, heterotrimeric G protein coupled family (GPCRs) receptors.

This assay works best with Gi-coupled receptors. Upon activation of the GPCR by an agonist, the receptor changes conformation exposing a binding site for a G-protein complex. Once this G-protein complex is bound, the Gα protein can release GDP and bind GTP. These types of assays are sometimes referred to as a GTP exchange assay. Because the GTP used in this assay is a radiolabeled non-hydrolyzable analog ([35S]-GTPγS, which is GTP labeled on the gamma phosphate with 35S), you will be able to measure the activation of the GPCR being studied by measuring the amount of [35S]-GTPγS bound to the receptor.

Functional Assays can be used to:

Determine the pharmacological values of potency (EC50) & efficacy (EMAX) of the ligand to activate the GPCR of interest.

Visualize regional differences of activated GPCRs by a ligand using Functional Autoradiography.

Determine if the ligand is a full agonist, partial agonist, inverse agonist or antagonist.

We offer three different custom services

Functional Autoradiography

This technique combines the advantages of receptor autoradiography and [35S]-GTPγS binding, providing anatomical and functional (EC50 & EMAX) information.

Functional Binding Assay

in vitro high-throughput [35S]-GTPγS binding assays are a powerful method used to measure the activation of G protein-coupled receptors (GPCRs) by a ligand (EC50 & EMAX).

in vitro Functional Assay & Screening List

Specializing in both standard and custom in vitro functional assays, we are focused on providing the right assays for assessing a GPCR therapeutic's potential efficacy...

Case Studies