Expression of human intestinal dipeptide transporter in Xenopus laevis oocytes.

The human colon adenocarcinoma cell line Caco-2 retains the H+/dipeptide cotransporter. To identify the structure of the human dipeptide transporter, we have examined the expression of the transporter in Xenopus laevis oocytes injected with Caco-2 poly(A)+RNA, by monitoring the uptake of bestatin, a dipeptide-like anticancer agent. The bestatin uptake in the poly(A)+RNA-injected oocytes was inhibited by excess glycyl-L-leucine, and showed pH dependence (optimal pH of 5.5-6.0). These observations suggest that the human intestinal dipeptide transporter can be expressed functionally in Xenopus oocytes.