EXPRESSION CLONING OF GABA(B) RECEPTORS UNCOVERS SIMILARITY TO METABOTROPIC GLUTAMATE RECEPTORS

GABA (gamma-amino-butyric acid), the principal inhibitory neurotransmi tter in the brain, signals through ionotropic (GABA(A)/ GABA(C)) and m etabotropic (GABA(B)) receptor systems. Here we report the cloning of GABA(B) receptors. Photoaffinity labelling experiments suggest that th e cloned receptors correspond to two highly conserved GABA(B) receptor forms present in the vertebrate nervous system. The cloned receptors negatively couple to adenylyl cyclase and show sequence similarity to the metabotropic receptors for the excitatory neurotransmitter L-gluta mate.