Fig. 6: Regulated metal release from the transport site into the cytoplasm.
From: Molecular insights into substrate translocation in an elevator-type metal transporter
A At normal or low zinc concentration, the metal released from the M1 site preferentially moves through Path 1 via the M3 site, where the histidine residue(s) in the IL2 participates in metal chelation, and is then slowly released into the cytoplasm. The question mark indicates that it is uncertain whether H151 is involved in binding Zn2+ during the release process, as it is not suggested by MTD simulation. B At high intracellular zinc concentration, the M3 site is occupied by a zinc ion from the cytoplasm, which blocks Path 1. Metal can be released into the cytoplasm only through Path 2 at a slower rate. In either scenario, the IL2 negatively regulates the transport activity.
