Gamma-Aminobutyric acid (GABA) is the major inhibitory
transmitter of the vertebrate retina. The gene SLC32A1 encodes the vesicular inhibitory amino acid transporter (VIAAT, also called vesicular GABA transporter VGAT) (Jellali A et al, 2002). VIAAT is a proton-coupled amino acid antiporter, uptaking the inhibitory neurotransmitters GABA and glycine into synaptic vesicles in exchange for protons. This process is driven by the H+-ATPase, providing the driving force for uptake of these neurotransmitters. The protein is expressed throughout the terminal ends of horizontal cells of the retina.