The Interaction of the Lac Repressor Protein with DNA of the Lac Operon
The lac repressor is a tetrameric protein containing identical subunits of 37kD. It was originally isolated by binding it to the non-metabolizable inducer, IPTG (isopropylthiogalactoside). It binds specifically to the lac operon DNA, a process that is inhibited by IPTG. Each monomeric subunit has one binding site for IPTG. In this image, three of the four chains of the lac repressor are shown . Only two of these chains are shown interacting with the DNA. The double helical DNA is at the top of the picture.
You can rotate the molecule by left clicking on it and dragging the molecule for any view you like.
In the wire-frame structures, the individual chains are difficult to discern. Use the buttons below to highlight each chain. You can also use the chime menu for other manipulations. Right click on the molecule and follow the menu.
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DNA chain 1
Backbone |
DNA chain 2
Backbone |
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Repressor protein A
Backbone |
Repressor chain B
Backbone |
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Repressor chain C
Backbone |
Inhibitor/Activator
Backbone |
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© Richard Hunt, University of South Carolina School of Medicine