Figure 4. Evidence of cooperative nature of mGlu₄ PAM binding site.

(A) Specific binding of 10nM [³H]ML128 to CHO expressing mGlu₄ receptor was determined in the presence of increasing concentration of the natural agonist. Binding of [³H]ML128 without addition of glutamate is set as 1.0 and presented together with SD. (B) The ability of 10 nM cold ML128 or DFMPP to displace the [³H]ML128 (10nM) from its binding site was measured without or increased concentration of natural agonist. The binding of 10 nM [³H]ML128 was set as 1.0 and presented together with SD. (C) Competitive binding assay was done with single dose (10 nM) of hot [³H]ML128 and increased concentration of cold DFMPP. The specific radioactivity of 10 nM [³H]ML128 was set as 100 and presented together with SD. All measurements were performed in three parallels and analyzed with GraphPad Prism.