Figure 1.

Comparison of the interactions of L^d versus D^b heavy chains with β₂m. The Cα trace of L^d/β₂m (Left, green) and D^b/β₂m (Right, blue) are shown. The heavy chain residues that interact with β₂m are highlighted: yellow, vdw; red, H-bonds; pink, both. Domains α1 and α2 of L^d are related by a 175° rotation followed by a 0.39-Å translation compared with a 177° rotation followed by a 0.12-Å translation for D^b and a 176° rotation followed by a 0.09-Å translation in K^b. Furthermore, the α3 domain of L^d and β₂m are related by a 142° rotation and a 13-Å translation, whereas in D^b these domains are related by a 141° rotation and 14-Å translation and in K^b a rotation of 139° and a translation of 14 Å. The decreased number of bonds of L^d versus D^b with β₂m result from differences in the orientation of the domains.