Solute carrier family 17 member 5 (SLC17A5) is also called sialin, H(+)/nitrate cotransporter, H(+)/sialic acid cotransporter (AST), membrane glycoprotein HP59, or vesicular H(+)/aspartate-glutamate cotransporter, transports glucuronic acid and free sialic acid out of the lysosome after its cleavage from sialoglycoconjugates, which is required for normal CNS myelination. It also mediates the membrane potential-dependent uptake of aspartate and glutamate into synaptic vesicles and synaptic-like microvesicles [, , , , , , , , ]. In the plasma membrane, it functions as a nitrate transporter []. Recessive mutations in the SLC17A5 gene cause the allelic disorders, Infantile sialic acid storage disease (ISSD) and Salla disease (a predominantly neurological disorder) [, , , ]. MFS proteins are thought to function through a single substrate binding site,alternating-access mechanism involving a rocker-switch type of movement.
