G Protein-coupled Receptor - Receptor Oligomerization

Receptor Oligomerization

G-protein-coupled receptor oligomerisation is a widespread phenomenon. One of the best-studied example is the metabotropic GABA_B receptor. This so-called constitutive receptor is formed by heterodimerization of GABA_BR1 and GABA_BR2 subunits. Expression of the GABA_BR1 without the GABA_BR2 in heterologous systems leads to retention of the subunit in the endoplasmic reticulum. Expression of the GABA_BR2 subunit alone, meanwhile, leads to surface expression of the subunit, although with no functional activity (i.e., the receptor does not bind agonist and cannot initiate a response following exposure to agonist). Expression of the two subunits together leads to plasma membrane expression of functional receptor. It has been shown that GABA_BR2 binding to GABA_BR1 causes masking of a retention signal of functional receptors.