Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system, causing a hyperpolarization of the membrane through the opening of a Cl- channel associated with the GABAA receptor (GABAA-R) subtype. GABAA-Rs are important therapeutic targets for a range of sedative, anxiolytic, and hypnotic agents and are implicated in several diseases including epilepsy, anxiety, depression, and substance abuse. The GABAA-R is a multimeric subunit complex. To date six (s, four (s and four (s, plus alternative splicing variants of some of these subunits, have been identified (Olsen and Tobin, 1990, Whiting et al., 1999, Ogris et al., 2004). Injection in oocytes or mammalian cell lines of cRNA coding for (- and (-subunits results in the expression of functional GABAA-Rs sensitive to GABA. However, co-expression of a (-subunit is required for benzodiazepine modulation. The various effects of the benzodiazepines in brain may also be mediated via different (-subunits of the receptor (McKernan et al., 2000, Mehta and Ticku, 1998, Ogris et al., 2004, Pöltl et al., 2003). Lastly, phosphorylation of (-subunits of the receptor has been shown to modulate GABAA-R function (Brandon et al., 2003). Anti-GABAA Receptor, (2-Subunit Western blot of 10 (g of rat hippocampal lysate showing immunolabeling of the ~46k (2-subunit of the GABAA-R.