GABA is the major inhibitory neurotransmitter in the CNS. GABAC receptors (rho1-3) belong to the Cys-loop family of ligand-gated ion channels and can form homo-pentameric receptors. The agonist and/or competitive antagonist binding site is formed by residues located on five discontinuous regions of the N-terminal region referred to as loops A-E at the interface of two rho subunits. There is strong evidence suggesting all members of the Cys-loop family share similar 3D structure. There is also a lot of interest in developing homology models of GABA receptors using acetylcholine-binding protein (AChBP) crystal structure. Herein, we explore the conformation of how GABA binds to GABAC receptors using S- and R-enantiomers of 3-fluoro-GABA (S- and R-3F-GABA) expressed in Xenopus oocytes using two-electrode voltage clamp methods. Furthermore, we also explored the role of tyrosine 102 (Y102) located on loop D on rho1 receptors. The substitution of Y102 with serine (Y102S) produces constitutively active receptors and the antagonist 3-APMPA was shown to be an inverse agonist. Y102 was also mutated to serine, cysteine and alanine (Y102S, Y102C and Y102A), expressed in Xenopus oocytes to explore the effect of the receptor conformational changes on the activity of a range of structurally diverse GABA antagonists.