EAAT5

EAAT5 is a retina-enriched excitatory amino acid transporter that binds glutamate and couples transporter activity to a glutamate-gated Cl^- conductance^[1]. Mechanistically, EAAT5 links synaptic glutamate handling with inhibitory anion current, so glutamate released from photoreceptors and rod bipolar cells can activate local feedback within retinal circuits^[2]. In mouse retina, EAAT5 localizes close to glutamatergic release sites, and EAAT5^-/^- retinae show reduced flicker resolution in multielectrode-array recordings, supporting its role in temporal visual information processing^[3]. Compared with related isoforms, EAAT5 differs from high-capacity EAAT1/EAAT2 transporters because high chloride conductance is associated with less effective glutamate removal, whereas EAAT1 and EAAT2 remain major glutamate transporters in retina^[2][3]. At rod bipolar terminals, EAAT2 and EAAT5 coexist near release sites, but EAAT5 predominantly regulates temporal resolution at rod bipolar-to-AII amacrine synapses^[4]. Heterologous EAAT5 studies describe low-capacity transport and slow anion-channel gating, highlighting a distinction between EAAT5 channel-like behavior and classical glutamate uptake^[5]. For experimental applications, TBOA-based pharmacology, EAAT5 knockout retinae, and rapid glutamate uncaging in mouse rods provide practical systems to test EAAT5-dependent glutamate transport, chloride conductance, and synaptic timing^[3][6].