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Identification of the histidine residues involved in substrate recognition by a rat H + /peptide cotransporter, PEPT1
Author(s) -
Terada Tomohiro,
Saito Hideyuki,
Mukai Mayumi,
Inui Ken-ichi
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00952-0
Subject(s) - histidine , chemistry , biochemistry , cotransporter , peptide , microbiology and biotechnology , biology , amino acid , sodium , organic chemistry
The LLC‐PK 1 cells stably transfected with a rat PEPT1 cDNA transported ceftibuten (anion) and cephradine (zwitterion), both oral β‐lactam antibiotics, in a H + ‐gradient‐dependent manner. Diethylpyrocarbonate, a histidine residue modifier, abolished ceftibuten uptake. This inhibition was prevented in the presence of glycylsarcosine or cephradine. When expressed in Xenopus oocytes, replacement of either histidine 57 or histidine 121 of the rat PEPT1 with glutamine by site‐directed mutagenesis eliminated ceftibuten and [ 14 C]glycylsarcosine transport activities. Immunostaining of oocyte sections indicated that insertion of the mutant transporters in the plasma membranes was not impaired. These findings suggest that both histidine 57 and histidine 121, which are conserved in the rat, rabbit and human PEPT1, are involved in substrate recognition of this molecule.