Figure 4.

Investigating the reductive nature of intracellular compartments during folate-FR trafficking using FRET. The folate-FRET reporter #1 changes fluorescence from red to green upon disulfide reduction. After a 0.5-h incubation with 100 nM of reporter #1 and a subsequent wash step to remove unbound conjugates, KB cells were imaged with confocal microscopy (a) immediately or after (b) 2, (c) 6, or (d) 12 h of further incubation in culture medium by excitation at 488 nm. Scale bar = 10 μm.122 Copyright © 2006 National Academy of Sciences of the USA