Figure 2 - full size

 

Figure 2.
Fig. 2. Two monomers stabilized by tungsten clusters; the ligand-binding domains have been labeled R2 to R7 and R2* to R7*, respectively. The linkers between R4 and R5 and R4* and R5* meet at a crystallographic twofold axis. At a distance below, a cluster (center) sits on the twofold as well.

The above figure is reprinted by permission from the AAAs: Science (2002, 298, 2353-2358) copyright 2002.