Vanadium Transport and Binding Proteins

Vanadate transport in the erythrocyte was shown to occur via facilitated diffusion in erythrocyte membranes and was inhibited by 4,4 -diisothiocyanostilbene-2,2 -disulfonic acid (DIDS), a specific inhibitor of the band 3 anion transport protein [23], Vanadium is also believed to enter cells as the vanadyl ion, presumably through cationic facilitated diffusion systems. The divalent metal transporter 1 protein (called DMT1, and also known as Nramp2), which carries iron into cells in the gastrointestinal system and out of endosomes in the transferrin cycle [24], has been proposed to also transport the vanadyl cation. In animal systems, specific transport protein systems facilitate the transport of vanadium across membranes into the cell and between cellular compartments, whereas the transport of vanadium through fluids in the organism occurs via binding to proteins that may not be specific to vanadium. 

FIGURE 10.1 Ascidian vanadocyte. Modified from Reference 26. 

The binding of the insulin-enhancing compound bis(maltolato)oxovanadium (IV) (BMOV) to transferrin and albumin has been studied using EPR and compared to the binding of V0S04 with these proteins [28,29], Both proteins could be impor- 

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