Nucleoside:H(+) symporter family of the Major Facilitator Superfamily of transporters
The prototypical members of the Nucleoside:H(+) symporter (NHS) family are Escherichia coli nucleoside permease NupG and xanthosine permease. Nucleoside:H(+) symporters are proton-driven transporters that facilitate the import of nucleosides across the cytoplasmic membrane. NupG is a broad-specificity transporter of purine and pyrimidine nucleosides. Xanthosine permease is involved in the uptake of xanthosine and other nucleosides such as inosine, adenosine, cytidine, uridine and thymidine. The NHS 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.",