Fig. 7.

Effect of ubiquitin mutant Ub-K48R on PMA-regulated OAT1 surface expression. (A) OAT1-expressing cells were transfected with Ub-K48R (or vector as control), followed by treatment with or without PMA (1 μM) for 30 minutes. The treated cells underwent cell-surface biotinylation. Biotinylated proteins were isolated with streptavidin beads and analyzed by immunoblotting with an anti-myc antibody. (B) densitometry plot of results from (A) as well as from other experiments. Surface OAT1 in PMA-treated cells was expressed as the percentage of surface OAT1 in control cells. The values are mean ± S.E. (n = 3).