FIGURE 4.
cr-u-PAR promotes biotinylated-PAI-114–1B·tcu-PA complex internalization. 293 wt u-PAR (white bars) and cr-u-PAR (black bars) cells were incubated with 10 nm biotinylated-PAI-114–1B·tcu-PA complex at 4 °C, and internalization was initiated at 37 °C and terminated as described earlier. Cells were acid-washed to remove non-internalized cell-surface-bound biotinlyated-PAI-I14–1B·tcu-PA complex. Time points represent the duration of the 37 °C incubation plus the acid wash. Internalized biotinylated complex was detected as described with streptavidin-HRP, and the amount of complex internalized by wt u-PAR cells at 3 min was set as baseline. As a control, RAP (500 nm) was incubated with tcu-PA·PAI-1 with continuous addition of RAP following incubation for 30 min at 37 °C. Data represent the mean ± S.E. of minimum three independent replicates.