Two studies are highlighted where three-dimensional modeling of
protein networks within and between species provides insights into the
biophysics and evolution of biological systems. First, a structural
analysis of the yeast protein-protein interaction network reveals that
protein evolution is constrained by the biophysics of protein folding,
the mutational robustness of the native structure, and the biophysics
and function of protein-protein interactions. Second, a structural
analysis of human-virus protein-protein interaction networks reveals
distinct principles governing antagonism versus cooperation in
host-pathogen and within-host interactions.