Membrane topology of the human dipeptide transporter hPEPT1, determined by epitope insertions

Intestinal transporters are important in nutrient uptake and in mediating drug absorption. The human intestinal transporter hPEPT1 is a mediator in the absorption of dipeptides and tripeptides. The presence of 12 putative TMDs is suggested by the hydropathy plot of hPEPT1, although the hydropathy profile does not establish the amount and location of TMDs with certainty. The topology of hPEPT1 has been tested through insertion of epitope tags into intra or extracellular loops, to determine accessibilty tl anti-epitope antibodies.