A GABA_B Mystery: The Search for Pharmacologically Distinct GABA_B Receptors

Schematic representation of GABA_B receptor (GABA_BR) assembly and function. The biogenesis of functional GABA_BRs depends on distinct genes (GABBR1 and GABBR2), the expression of which results in distinct seven-transmembrane–domain products that undergo heterodimerization, followed by migration (trafficking) and insertion into the plasma membrane. Activation of the R1 protomer by GABA and Ca²⁺ is manifested through a number of transduction mechanisms that are mediated through association of the R2 protomer with a trimeric (α, β, γ) G protein.