Salmonella enterica Na+/melibiose symporter MelB and similar transporters of the Major Facilitator Superfamily
This family is composed of Salmonella enterica Na+/melibiose symporter MelB, Major Facilitator Superfamily domain-containing proteins, MFSD2 and MFSD12, and other sugar transporters. MelB catalyzes the electrogenic symport of galactosides with Na+, Li+ or H+. The MFSD2 subfamily is composed of two vertebrate members, MFSD2A and MFSD2B. MFSD2A is more commonly called sodium-dependent lysophosphatidylcholine symporter 1 (NLS1). It is an LPC symporter that plays an essential role for blood-brain barrier formation and function. Inactivating mutations in MFSD2A cause a lethal microcephaly syndrome. MFSD2B is a potential risk or protect factor in the prognosis of lung adenocarcinoma. MelB-like family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which 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.",