Figure 4.
Putative biologically relevant oligomeric state. The proteins associate as a tetramer (dimer of dimers) shown in cartoon (A) and space-filling (B) representations and colored by chain in all three structures even when crystallized in different space groups. The UNL is shown as red spheres. Arginine 163 from a neighboring protomer that interact with the UNL is shown in ball and stick representation.