title: Functional expression of the oligopeptide transporter PepT1 from the sea bass (Dicentrarchus labrax).
abstract: Complementary RNA, derived from the intestine of the sea bass Dicentrarchus labrax and putatively coding for a pH-dependent oligopeptide transporter PepT1 (SLC15 family), was injected in Xenopus oocytes that were subsequently tested with electrophysiological techniques. Transport-associated currents were observed when various di- or tripeptides were applied at concentrations ranging between 0.1 and 10 mM. No currents were generated by histidine nor by other single amino acids. Sea bass PepT1 also exhibited presteady-state currents in the absence of substrates. Acidic pH slowed down the relaxation time constant of these currents and shifted both Q/V and tau/V relationships toward more positive voltages. Michaelis-Menten analysis of the transport currents showed an increase in apparent substrate affinity at acidic pH, which was very similar to that exhibited by the related transporter from zebrafish (Danio rerio), but in contrast, did not demonstrate a significant effect of pH on the maximal transport current.
authors.affiliation: Department of Biotechnology and Molecular Sciences (DBSM), University of Insubria, Via J.H. Dunant, 3-21100, Varese, Italy.
authors.forename: Rachele
authors.initials: R
authors.lastname: Sangaletti
authors.forename: Genciana
authors.initials: G
authors.lastname: Terova
authors.forename: Antonio
authors.initials: A
authors.lastname: Peres
authors.forename: Elena
authors.initials: E
authors.lastname: Bossi
authors.forename: Samuela
authors.initials: S
authors.lastname: Corà
authors.forename: Marco
authors.initials: M
authors.lastname: Saroglia
mesh_terms: D000818:Animals; D001492:Bass / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D009865:Oocytes; D018408:Patch-Clamp Techniques; D000074011:Peptide Transporter 1; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis; D029961:Zebrafish Proteins
chemical_list: D000074011:Peptide Transporter 1; D027981:Symporters; D029961:Zebrafish Proteins; C000613207:slc15a1b protein, zebrafish