Fig. 4.
Cystine-bound cystinosin shows transient capacitive currents. (A) Cystinosin-ΔGYDQL-EGFP oocytes held at -40 mV were stepped to various potentials (Vstep) at pHout 7.5, with or without cystine. Subtracted (cystine-dependent) traces are shown. In B, time integrals of the current peaks observed after the first (ΔQON) and second (ΔQOFF) steps are plotted as a function of Vstep (means ± s.e.m. of 5 oocytes with similar expression level). Curves were fitted with a Boltzmann distribution function. In C, the steady-state current elicited at pHout 5.0 by 1 mM cystine is plotted against the amplitude of the Boltzmann function (Qmax) for 8 individual oocytes.