Figure 8.

HRP uptake and accumulation. Control and JAS-treated cells were incubated with HRP added to the apical (A) or basolateral (B) chamber over a time course (0, 5, 15, 30, 60, and 120 min) for continuous labeling or added to the basolateral chamber in a pulse–chase regime for 10 min followed by chase incubations of 20, 50, and 110 min (C). HRP uptake values were determined by measuring the HRP activity present in the cell lysate of each filter-grown monolayer and were normalized to the protein concentration of each sample. JAS pretreatment increased the uptake of HRP from the basolateral cell surface at all time points (B) compared with uptake in control cells but had no effect on the apical uptake of HRP (A). Pulse–chase labeling (C) shows an initial increased uptake in JAS-treated cells, followed by a loss of HRP (recycling) during the first 60 min and then sustained accumulation at a higher level than control cells. Points in A and B represent the average of two values (i.e., two filters). In graph C, each data point is the mean and SEM of four samples.