(Figure Presented) Tag it: Well-defined monomers, dimers, trimers, three-dimensional spherical shells, and two-dimensional ordered arrays of genetically engineered proteins were constructed by using functionalized gold nanoparticles. Nanoparticle size, functionality, and protein genetic motif contribute to the unique geometry, precise stoichiometry, given orientation, and high specificity of these nanoparticle-protein hybrid structures. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.