Selenocysteine is transported by EAATs 1–3.

<p><b>A)</b> Representative recordings (upper panel) and averaged normalized transport currents (lower panel) measured at −60 mV as a function of the L-selenocysteine concentration in EAAT3 expressing oocytes (n = 6). Data are presented as the mean and Std. dev. of the mean and fit with the Hill equation to estimate the Km for transport. <b>B)</b> Comparison of the maximal transport currents at −60 mV for L-selenocysteine and L-cysteine by EAAT1 (n>3), EAAT2 (n>5) or EAAT3 (n>10) normalized to the maximal currents induced by L-glutamate measured in the same oocyte. <b>C)</b> Comparison of averaged current-voltage relationships recorded from oocytes expressing EAAT3 for both 1 mM glutamate (red symbols, n = 4) and 1 mM selenocysteine (blue symbols, n = 4). Black symbols indicate the averaged current voltage relationship of the same cells in the absence of substrate (n = 4) and the solid line represents the average of water injected oocytes in the presence of 1 mM glutamate (n = 5).