Primary structure and properties of the Na⁺/glucose symporter (SglS) of Vibrio parahaemolyticus

Previously, we cloned and sequenced a DNA fragment from Vibrio parahaemolyticus and found four open rending frames (ORFs). Here, we clearly demonstrate that one of the ORFs, ORF1, is the gene (sglS) encoding a Na⁺/glucose symporter (SglS). We characterize the Na⁺/glucose symporter produced in Escherichia mutant (JM1100) cells which lack original glucose transport activity and galactose transport activity. We also show that phlorizin, a potent inhibitor of the SGLT1 Na⁺/glucose symporter of animal cells, inhibited glucose transport, but not galactose transport, via the SglS system.