PepT1 and PepT2 are Modular Proteins with Functionally Distinct Domains
(A) Homology model of the human PepT1 transporter generated using the crystal structure of MmPepT1ECD (colored blue to red as in Figure 1B) and the recently determined bacterial homolog PepTSo representing the transmembrane portion of the transporter (shown in gray). The peptide-binding site is highlighted (magenta).
(B) Kinetic analysis of Gly-Sar uptake in human PepT1 and PepT2 using the TEVC method.
(C) Kinetic analysis of Gly-Sar uptake in the PepT2ΔECD, PepT2T1ECD, and PepT1D573A constructs.
(D) Ki values for the different constructs for lysyl-lysine and cefaclor are shown, indicating no effect of removing the ECD on peptide or drug uptake in PepT2.