This transporter is found in the outer membranes of Gram-negative bacteria. It is a 12 stranded β-barrel protein. It has 2 binding sites for nucleosides inside the channel.

Hydrophobic residues are colored magenta, and polar residues are colored white.

Ye, J., Van Den Berg, B.
Crystal Structure of the Bacterial Nucleoside Transporter Tsx.
Embo J. 23 pp. 3187 (2004)
(PubMed)

1tlw (PDB)