FIGURE 1.
Modification of EAAT2-mediated glutamate transport by C-terminal truncations. A, predicted transmembrane topology of EAATs based on (36) and sequence alignment of TM8 with subsequent C terminus. A unique caspase-3 cleavage motif in EAAT2 is represented by the sequence DTID; the asterisk points at the cleavage location. B, mean values of glutamate transport current amplitudes at −185 mV for tsA201 cells expressing WT or truncated EAAT2 in the presence of external NaCl (gray bars) or Na-gluconate (open bars) (n as indicated). The inset gives representative current recordings for WT EAAT2 in the absence or in the presence of 0.5 mm l-glutamate. C, confocal images and corresponding profile intensities of WT and truncated EAAT2 (scale bar = 5 μm). Insets show the predicted topology of WT and C-terminally truncated EAAT2 with schematic localization of the N-terminally linked mYFP fusion protein. D, current responses of cells expressing WT and E500X EAAT2 to application of 2, 142 mm K+, or 0.5 mm TBOA at 0 mV. The internal solution contained 115 mm Na-l-glutamate. Dotted lines represent 0 pA. E, K+-dependence of reverse glutamate transport. Mean values of current responses at 0 mV for WT (▾) or E500X (■).