The lac repressor is composed of .

Each of the subunits is composed of two clearly distinct domains.

Compare the distribution of amino acids with that of the residues (you can also look at .

Each subunit is composed of two

Looking at one of the , we can see what kind of structure it represents. This can be seen better if we view it in or mode.

OK, is better?

See of the tetramer

Figure 1-41