FIGURE 1.

ZnMP export by FLVCR is carrier protein-dependent. NRK/FLVCR cells were loaded with 5 μm ZnMP for 30 min (upper panel) and then washed and cultured for 90 min in the absence or presence of either bovine serum albumin (middle panels) or hemopexin (lower panels) at the indicated concentrations. The retained intracellular ZnMP was visualized by fluorescence microscopy. Export was comparable with 1.515 μm hemopexin and 151.5 μm albumin. No export occurred when a heme-binding protein was absent (0 μm albumin). NRK/Neo cells failed to export ZnMP (data not shown). Scale bar = 200 μm.