The 'ABC' of GABA receptors

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