Inferred domain interactions of G-protein subunits. (a) Domain structures of interacting G-γ and G-β proteins in human, mouse and yeast. Protein names are in black to the left of each protein's domain structure schematic. Domains of proteins are colored boxes connected by a gray line. Pfam-A domain names and Pfam-B accession numbers are the same color as the domains they label. Domain structures are schematic and are not to scale. (b) Of the possible domain interactions, only that of G-gamma [Pfam:PF00631] and a Pfam-B domain [Pfam:PB002804] is inferred with high confidence (E = 12). (c) A published structure of complexed G-protein γ and β subunits [PDB:1GP2]  confirms our prediction that the G-gamma and PB002804 domains can interact.