Transport of amino acid aryl amides by the intestinal H+/peptide cotransport system, PEPT1.
Transport of amino acid aryl amides by the intestinal H+/peptide symporter (PEPT1) was studied in Caco-2 cells and in Xenopus laevis oocytes expressing human PEPT1. Several amino acid amides were able to inhibit the uptake of [14C]glycylsarcosine in Caco-2 cells. Ala-4-nitroanilide (Ki = 0.08 mM), Phe-4-nitroanilide (Ki = 0.09 mM) and Ala-4-phenylanilide (Ki = 0.03 mM) were accepted as substrates with equal or higher affinity than natural Ala-Xaa dipeptides. Ala-anilide (Ki = 2.9 mM), Ala-7-amido-4-methylcoumarin (Ki = 0.2 mM), Ala-4-chloroanilide (Ki = 0.3 mM) and Ala-4-methylanilide (Ki = 0.3 mM) were also recognized by PEPT1 as substrates. In contrast, alanine, Ala-amide, Phe-amide, Ala-methyl ester, Ala-4-nitrobenzyl ester and Ala-methylamide were not recognized (Ki > 20 mM). In X. laevis oocytes, transport of Ala-4-nitroanilide, Ala-7-amido-4-methylcoumarin, Ala-4-methylanilide and Ala-anilide was associated with transfer of positive charge and the currents were saturable with respect to substrate concentration (K0.5 values: 0.1, 0.2, 0.8 and 3.1 mM, respectively). The currents induced by Ala-4-methylanilide were saturable with respect to the substrate concentration and influenced by the membrane potential. The affinity of the transporter for Ala-4-methylanilide was also found to be influenced by the membrane potential. We conclude that the intestinal H+/peptide cotransport system PEPT1 accepts amino acid aryl amides as substrates.
Börner
V
V
Institute of Biochemistry, Department of Biochemistry/Biotechnology, Martin-Luther-University Halle-Wittenberg, Germany.
Fei
Y J
YJ
Hartrodt
B
B
Ganapathy
V
V
Leibach
F H
FH
Neubert
K
K
Brandsch
M
M
D000577:Amides / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D000074011:Peptide Transporter 1; D027981:Symporters; D014982:Xenopus laevis
D000577:Amides; D000596:Amino Acids; D002352:Carrier Proteins; D000074011:Peptide Transporter 1; C082186:SLC15A1 protein, human; D027981:Symporters