General Chemistry Labs

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:

  1. The 4-fold channel, which is lined with leucine residues, is hydrophobic ("water-hating," lined with nonpolar side chains);
  2. The 3-fold channel, which is lined with glutamate and aspartate residues, is hydrophilic ("water-loving," lined with polar side chains).

4-FOLD CHANNEL

4 Fold Net

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.


3-FOLD CHANNEL

3 Fold Net

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.


Residues that Comprise the Two Channels

View the three (3) residues involved by clicking here.


Return to Structural-Overview Section of Tutorial

Return to Questions on the Overview Section of Tutorial

Return to Questions on the Iron-removal Section of Tutorial