Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1

<p>The characteristics of transport by the epithelial, proton-coupled oligopeptide transporter, PepT1, have been investigated in PepT1 expressing <em>Xenopus laevis</em> oocytes using electrophysiological techniques.</p> <p>Membrane depolarisations and inward currents...

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Main Authors: Beattie, L, Lorraine A. Beattie
Other Authors: Boyd, C
Format: Thesis
Language:English
Published: 2001
Subjects:
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author Beattie, L
Lorraine A. Beattie
author2 Boyd, C
author_facet Boyd, C
Beattie, L
Lorraine A. Beattie
author_sort Beattie, L
collection OXFORD
description <p>The characteristics of transport by the epithelial, proton-coupled oligopeptide transporter, PepT1, have been investigated in PepT1 expressing <em>Xenopus laevis</em> oocytes using electrophysiological techniques.</p> <p>Membrane depolarisations and inward currents have been measured in response to various dipeptide substrates, including structurally modified and charged peptides. The latter part of this study has focussed on the role of phorbol esters on the regulation of PepT1-mediated peptide transport.</p> <p>I have shown that transport of neutral peptides is dependent on both pH and membrane potential. In addition, the carboxyl terminus plays an important role in substrate recognition and binding, as when blocked, the affinity of the substrate is reduced 10-fold. The importance of position of charge within a dipeptide on substrate binding has also been investigated using dipeptides where the charged amino acid residue is present at either the amino or carboxyl terminus. The results showed that the apparent order of affinity reversed upon extracellular acidification, thus charged residues within the peptide play an important role in substrate binding.</p> <p>The acute regulation of the oligopeptide transporter has been examined by studying the effects of phorbol esters on the transport of a neutral peptide, Gly-Gln. The active ester, PMA, was shown to decrease both the K<sub>a</sub> and the I<sub>max</sub>. Immunocytochemical studies have confirmed the electrophysiological findings.</p>
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spelling oxford-uuid:2213d293-14cd-483b-88ab-7395e5c39b0c2024-12-01T18:08:39ZElectrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1Thesishttp://purl.org/coar/resource_type/c_db06uuid:2213d293-14cd-483b-88ab-7395e5c39b0cPhysiological transportXenopus laevisNeuropeptidesOligopeptidesEnglishPolonsky Theses Digitisation Project2001Beattie, LLorraine A. BeattieBoyd, CBoyd, R<p>The characteristics of transport by the epithelial, proton-coupled oligopeptide transporter, PepT1, have been investigated in PepT1 expressing <em>Xenopus laevis</em> oocytes using electrophysiological techniques.</p> <p>Membrane depolarisations and inward currents have been measured in response to various dipeptide substrates, including structurally modified and charged peptides. The latter part of this study has focussed on the role of phorbol esters on the regulation of PepT1-mediated peptide transport.</p> <p>I have shown that transport of neutral peptides is dependent on both pH and membrane potential. In addition, the carboxyl terminus plays an important role in substrate recognition and binding, as when blocked, the affinity of the substrate is reduced 10-fold. The importance of position of charge within a dipeptide on substrate binding has also been investigated using dipeptides where the charged amino acid residue is present at either the amino or carboxyl terminus. The results showed that the apparent order of affinity reversed upon extracellular acidification, thus charged residues within the peptide play an important role in substrate binding.</p> <p>The acute regulation of the oligopeptide transporter has been examined by studying the effects of phorbol esters on the transport of a neutral peptide, Gly-Gln. The active ester, PMA, was shown to decrease both the K<sub>a</sub> and the I<sub>max</sub>. Immunocytochemical studies have confirmed the electrophysiological findings.</p>
spellingShingle Physiological transport
Xenopus laevis
Neuropeptides
Oligopeptides
Beattie, L
Lorraine A. Beattie
Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1
title Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1
title_full Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1
title_fullStr Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1
title_full_unstemmed Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1
title_short Electrophysiological analysis of the epithelial H+/oligopeptide transporter, PepT1
title_sort electrophysiological analysis of the epithelial h oligopeptide transporter pept1
topic Physiological transport
Xenopus laevis
Neuropeptides
Oligopeptides
work_keys_str_mv AT beattiel electrophysiologicalanalysisoftheepithelialholigopeptidetransporterpept1
AT lorraineabeattie electrophysiologicalanalysisoftheepithelialholigopeptidetransporterpept1