Coiled-coil protein-origami cages self-assemble in cells

Protein cages based on coiled coil units can self-assemble in bacteria and mammalian cells. A tetrahedron, rectangular pyramid and trigonal prism cages of 5 to 10 nm diameters were designed. The prism, composed of more than 700 amino acid residues, represents the largest single-chain designed protein. Potential applications include drug delivery, vaccines, enzyme encapsulation, smart biomaterials, biosensors and molecular machines.