THE CHANNELS IN FERRITIN
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Introduction
The role of the channels in both the iron-formation and
iron-removal processes is dependent on the structural differences
between the 2 channels. In this link, the residues that comprise
the channels and the structural differences between these
residues are examined.
The intersections of the subunits form two (2) types of
channels:
- The 4-fold channel, which is lined with leucine residues,
is hydrophobic ("water-hating," lined with
nonpolar side chains);
- The 3-fold channel, which is lined with glutamate and
aspartate residues, is hydrophilic
("water-loving," lined with polar side chains).
4-FOLD CHANNEL
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Channel Figure 1:
This is a molecular model of the 4-fold channel with
the four (4) intersecting subunits represented as ribbons
and the side chains lining the channel represented as CPK
models. (In this picture, the ribbons have the same color
code as the subunits in Figure 1 in the main section of
this tutorial.) The carbon atoms in the side chains
lining the channel are shown in green and represented as
CPK models. Hydrogens are omitted from the picture for
visual clarity.
Notice that there are no polar groups containing
oxygen lining this channel. This results in the channel
having a hydrophobic nature.
Note: The carbon atoms are green, the nitrogen
atoms are blue, and the oxygen atoms are red in this CPK
represntation.
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3-FOLD CHANNEL
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Channel Figure 2:
This is a molecular model of the 3-fold channel with
the three (3) intersecting subunits represented as
ribbons. (In this picture, the ribbons have the same
color code as the subunits in Figure 1 in the main
section of this tutorial.) The amino-acid residues lining
the channel are shown as CPK models.
Notice the polarity of the carboxylate side chains on
the residues lining the 3-fold channel; the polar nature
of these side chains results in this channel being
hydrophilic.
Note: The carbon atoms are green, the nitrogen
atoms are blue, and the oxygen atoms are red in this CPK
representation.
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View the three (3) residues involved by clicking here.
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Structural-Overview Section of Tutorial
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the Overview Section of Tutorial
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the Iron-removal Section of Tutorial