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Peptide mimics as substrates for the intestinal peptide transporter.

Authors
  • Temple, C S
  • Stewart, A K
  • Meredith, D
  • Lister, N A
  • Morgan, K M
  • Collier, I D
  • Vaughan-Jones, R D
  • Boyd, C A
  • Bailey, P D
  • Bronk, J R
Type
Published Article
Journal
The Journal of biological chemistry
Publication Date
Jan 02, 1998
Volume
273
Issue
1
Pages
20–22
Identifiers
PMID: 9417040
Source
Medline
License
Unknown

Abstract

4-Aminophenylacetic acid (4-APAA), a peptide mimic lacking a peptide bond, has been shown to interact with a proton-coupled oligopeptide transporter using a number of different experimental approaches. In addition to inhibiting transport of labeled peptides, these studies show that 4-APAA is itself translocated. 4-APAA transport across the rat intact intestine was stimulated 18-fold by luminal acidification (to pH 6.8) as determined by high performance liquid chromatography (HPLC); in enterocytes isolated from mouse small intestine the intracellular pH was reduced on application of 4-APAA, as shown fluorimetrically with the pH indicator carboxy-SNARF; 4-APAA trans-stimulated radiolabeled peptide transport in brush-border membrane vesicles isolated from rat renal cortex; and in Xenopus oocytes expressing PepT1, 4-APAA produced trans-stimulation of radiolabeled peptide efflux, and as determined by HPLC, was a substrate for translocation by this transporter. These results with 4-APAA show for the first time that the presence of a peptide bond is not a requirement for rapid translocation through the proton-linked oligopeptide transporter (PepT1). Further investigation will be needed to determine the minimal structural requirements for a molecule to be a substrate for this transporter.

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