Figure 2.

Model of a dimeric family C GPCR in its open–open/resting (left) and open–closed/active (right) conformations. The two conformations are in equillibrium with each other and additional conformations (not shown). Agonists and antagonists will shift the equillibrium towards the active or resting conformation respectively. The localizations of the Venus flytrap (VFT) domain, cysteine-rich domain (CRD) and seven transmembrane domain (7TM) are indicated. The models were constructed with the program MacPyMol using coordinates from PDB files 1EWT (mGlu₁ open–open/resting VFT), 1EWK (mGlu₁ open–closed/active VFT), 2E4U (mGlu₃ CRR) and 2R4S (β₂-adrenergic receptor 7TM). GPCR, G-protein-coupled receptor; mGlu, metabotropic glutamate.