Peptide transporter isoforms are discriminated by the fluorophore‐conjugated dipeptides β‐Ala‐ and d‐Ala‐Lys‐N‐7‐amino‐4‐methylcoumarin‐3‐acetic acid

Physiological Reports

Gabor Kottra¹  Britta Spanier¹  Tiziano Verri² 

[1] ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany;Laboratory of General Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy

关键词: Caenorhabditis elegans;    di‐ and tripeptide;    PEPT1;    PEPT2;    substrate specificity;    transporter;   

DOI  :  10.1002/phy2.165

来源: Wiley

【 摘 要 】

Abstract

Peptide transporters of the SLC15 family are classified by structure and function into PEPT1 (low-affinity/high-capacity) and PEPT2 (high-affinity/low-capacity) isoforms. Despite the differences in kinetics, both transporter isoforms are reckoned to transport essentially all possible di- and tripeptides. We here report that the fluorophore-conjugated dipeptide derivatives β-Ala-Lys-N-7-amino-4-methylcoumarin-3-acetic acid (β-AK-AMCA) and d-Ala-Lys-N-7-amino-4-methylcoumarin-3-acetic acid (d-AK-AMCA) are transported by distinct PEPT isoforms in a species-specific manner. Transport of the fluorophore peptides was studied (1) in vitro after heterologous expression in Xenopus oocytes of PEPT1 and PEPT2 isoforms from different vertebrate species and of PEPT1 and PEPT2 transporters from Caenorhabditis elegans by using electrophysiological and fluorescence methods and (2) in vivo in C. elegans by using fluorescence methods. Our results indicate that both substrates are transported by the vertebrate “renal-type” and the C. elegans “intestinal-type” peptide transporter only. A systematic analysis among species finds four predicted amino acid residues along the sequence that may account for the substrate uptake differences observed between the vertebrate PEPT1/nematode PEPT2 and the vertebrate PEPT2/nematode PEPT1 subtype. This selectivity on basis of isoforms and species may be helpful in better defining the structure–function determinants of the proteins of the SLC15 family.

【 授权许可】

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© 2013 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

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