The 'ABC' of GABA receptors

In the conventional view, GABA acts at either ionotropic GABA(A) or metabot ropic GABA(B) receptors. Recently, novel ionotropic GABA receptors that are composed of rho-subunits have been identified in the vertebrate retina. Th ese bicuculline- and baclofen-insensitive GABA receptors are frequently cal led GABA(C), following an early suggestion by Graham Johnston and colleague s. An IUPHAR committee has recommended that the term GABA(C) be avoided and subclassifies the retinal receptors as GABA(A0r). However, new evidence re garding the pharmacology, structure, function, genetics and cellular locali zation of ionotropic GABA receptors strengthens the case for the existence of two major classes of these receptors, GABA(A) and GABA(C).