Fig. 5.

The properties of the threefold ion channel in ferritin. Electrostatic surface representation of a trimer of L-ferritin subunits where three monomers (gray schematic) come in contact generating a threefold channel responsible for iron entry. The external (Left) and the internal (Right) views of the pore circled with black lines show the negatively charged environment, due to the presence of conserved Asp131, Glu134, and Thr135 side chain residues. In HoLf, in position 135, there is a Ser, which is highly similar to Thr.