Solute carrier family 17 member 5 (also called sialin) of the Major Facilitator Superfamily of transporters
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. It 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). SLC17A5 belongs to the Solute carrier 17 (SLC17) family of the Major Facilitator Superfamily (MFS) of membrane transport proteins. MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
Jiyao W et al.(2023). "The conserved domain database in 2023.",