The assembly of GABAA-R as heteropentamers produces complex heterogeneity in their structure, which is the major determinant of their pharmacological profile (Barnard et al., 1998; Olsen & Sieghart, 2008). The various receptor subtypes differ in abundance in cells throughout the nervous system and thus in functions related to the circuits involved. Available techniques do not allow us to unequivocally establish the subunit composition and arrangement of GABAA receptors in vivo, but this review summarizes our attempts to establish criteria for designating a proposed receptor heterooligomeric subtype as a native receptor, and our current opinion of which subtypes meet these criteria (Olsen & Sieghart, 2008).
