"Large protein complexes can be designed and created using smaller protein building blocks that self-assemble. David Baker at the University of Washington, Seattle, and his team report a method for producing such proteins. The authors simulate the docking of protein building blocks in desired architectures and then design amino-acid sequences for these blocks that result in low-energy interfaces between the blocks, driving self-assembly. The researchers incorporate the genes that encode the designed blocks into the bacterium Escherichia coli, which produces the proteins that then spontaneously self-assemble into the target architectures. The team created two cage-like proteins: one consisting of 24 building blocks in a 13-nanometre-wide complex with octahedral symmetry (pictured) and another comprising 12 subunits with an 11-nanometre-wide tetrahedral symmetry."