FIGURE 5.

Substitution analysis of Tyr-705 and effect of DTT on glycine transport. Transiently transfected COS7 cells expressing wild-type GlyT2 or mutants with the indicated amino acids at position 705, were subjected to biotinylation as described in Fig. 4 to determine plasma membrane expression (A) or treated with vehicle or 12 mm DTT (B) or 2.5 mm DTT (D) or the specified concentrations of the indicated reducing agents (C) and then assayed for [³H]glycine transport. In B, * indicates significantly different from wild-type GlyT2, p < 0.05 in Student's t test. In C and D, ** indicates p < 0.01, and * indicates p < 0.05 by analysis of variance. Lanes T, total proteins; lanes NB, nonbiotinylated proteins; lanes B, biotinylated proteins.