Solute carrier family 18 member B1 of the Major Facilitator Superfamily of transporters
Solute carrier family 18 member B1 (SLC18B1) is the fourth member of the SLC18 transporter family, which includes vesicular monoamine transporters and vesicular acetylcholine transporter. It is predominantly expressed in the hippocampus and is associated with vesicles in astrocytes. It actively transports spermine and spermidine by exchange of H(+), and has been suggested to be a vesicular polyamine transporter (VPAT). SLC18B1 belongs to the bacterial MdtG-like and eukaryotic solute carrier 18 (SLC18) family of the Major Facilitator Superfamily (MFS) of transporters. 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.",