Figure 6.

A Model for the Interaction between Trypsin and the Mammalian Peptide Transporters

During protein digestion in the small intestine, trypsin transiently docks onto the conserved di-acidic motif on the trypsin-binding domain, localizing the protease to the main site of peptide import on the brush border membrane. Localization would create an increase in the local concentration of arginine- and lysine-containing peptides (shown here as blue circles), which would be expected to increase the efficiency of their uptake into the cell.