Unified modeling of the mammalian and fish proton-dependent oligopeptide transporter PepT1

• DOI: 10.4161/chan.5.1.13505
• Publication Date: 2010-12-07T19:51:42Z
• Authors: Maria Daniela Renna; Rachele Sangaletti; Elena Bossi; Francesca Cherubino; Gabor Kottra; Antonio Peres
• Keywords: Oligopeptide

Electrophysiological and biophysical analyses were used to compare the partial complete transport cycles of intestinal oligopeptide transporter PepT1 among three species (seabass, zebrafish rabbit). On whole, presteady-state currents fish transporters similar each other. Rabbit differed from by having slower-decaying currents, charge vs. potential (Q/V) time constant (τ/V) curves shifted more positive potentials. All isoforms similarly affected external pH, showing acidity-induced slowing transients shifts in Q/V τ/V curves. Analysis pH-dependence unidirectional rates intramembrane movement suggested that protonation protein limits speed this process both directions. The cycle was studied using neutral dipeptide Gly-Gln. Michaelis-Menten analysis confirmed that, all species, acidity significantly increases apparent affinity for substrate but does not strongly impact maximal current. Simulations a kinetic model incorporating new findings showed good agreement with experimental data respect currents.