4qnd is a 1 chain structure with sequence from Vibrio sp. N418. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
SWEET_VIBSN The homodimer mediates transmembrane sugar transport down a concentration gradient. Transport is probably effected by rocking-type movements, where a cargo-binding cavity opens first on one and then on the other side of the membrane.[UniProtKB:B0SR19]