The ‘ABC’ of GABA receptors

In the conventional view, GABA acts at either ionotropic GABAA or metabotropic GABAB receptors. Recently, novel ionotropic GABA receptors that are composed of ρ-subunits have been identified in the vertebrate retina. These bicuculline- and baclofen-insensitive GABA receptors are frequently called GABAC, following an early suggestion by Graham Johnston and colleagues. An IUPHAR committee has recommended that the term GABAC be avoided and subclassifies the retinal receptors as GABAA0r. 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, GABAA and GABAC.