EAAT5

EAAT5, also known as SLC1A7, is a member of the excitatory amino acid transporter family. It is a glutamate transporter with distinctive properties compared to other EAATs and is encoded by the SLC1A7 gene. In humans, EAAT5 is primarily expressed in the retina, with additional expression reported in certain brain regions, though its retinal role is the most studied.

In the retina, EAAT5 is localized to neurons involved in synaptic transmission, including presynaptic terminals in photoreceptors and related retinal neurons. Its activity contributes to the clearance of extracellular glutamate, helping to terminate synaptic signals and prevent excitotoxicity. A hallmark of EAAT5 is its prominent glutamate-activated anion conductance, which can influence membrane potential and synaptic signaling independent of the classic transporter function. Thus, EAAT5 participates in both glutamate clearance and in shaping the temporal dynamics of glutamatergic signaling in retinal circuits.

Biochemically, EAAT5 is a sodium- and proton-coupled transporter that uses the transmembrane gradients of Na+, H+, and K+ to drive glutamate uptake. It forms homotrimers in the membrane and possesses eight transmembrane segments, like other EAAT family members. In addition to transport, the transporter mediates a sizeable anion conductance when activated by glutamate, a feature particularly relevant to retina physiology.

Clinical relevance for EAAT5 is an area of ongoing research. While direct disease associations are not as well established as for some other EAATs, EAAT5 is considered important for retinal glutamate regulation and may contribute to retinal signaling abnormalities if its function is disrupted. Research continues to clarify its exact roles in vision and potential implications for retinal disorders.