[History and the present of metabotropic GABAB receptor].

GABAB receptor is the main inhibitory metabotropic receptor in mammalian central nervous system. This receptor is a member of the Family 3 G-protein coupled receptors (GPCR). It is related to the metabotropic glutamate receptors, the calcium-sensing receptor and some vomeronasal receptors. The receptor is a heterodimer consisting of two subunits designated BR1 and BR2. Presynaptically. GABAB suppresses transmitter release via inhibition of Ca2+ channels, postsynaptically it increases K+ conductance resulting in hyperpolarization. The receptor is coupled to Gi/Go proteins and its activation can inhibit adenylyl cyclase activity. GABAs is widely distributed in CNS and peripheral tissues and plays an important role in many physiological and pathological processes. Recently, a novel GPCR with close relation to GABAB was cloned. It was termed GABABL, its role in GABAB activation has not been discovered yet.