Transport and recognition of aminopeptidase-resistant cellobiose-coupled tyrosylglycylglycine by intestinal Na+/glucose cotransporter (SGLT1):: Recognition of sugar conjugates by SGLT1 is much less restricted than transport

Transport and recognition of aminopeptidase-resistant cellobiose-coupled tyrosylglycylglycine (CcpTGG) by intestinal Na+/glucose cotransporter (SGLT1) was examined in rat small intestine. Inhibitory effect of phloridzin (SGLT1 inhibitor) on the CcpTGG transport was extremely low: Concentration dependence of the CcpTGG transport was observed, but the primary component of transport was passive diffusion. However, CcpTGG significantly inhibited SGLT1-mediated transport, indicating its recognition by SGLT1. Other glucose-conjugates also inhibited SGLT1-mediated transport. These results indicate that recognition of sugar conjugates by SGLT1 is much less restricted than transport, and that it should be relatively easier to design SGLT1 inhibitors than SGLT1-transportable sugar conjugates.