(A) Environmental and membrane family matrix construction. (B) Pairwise correlations. Types of correlations that can be performed: (1) between either environmental features (Env-Env) or membrane protein families (Fam-Fam); (2) between an environmental feature and a membrane protein family (Env-Fam); or (3) between two sites (Site-Site) defined either through their membrane protein families (SS-FAM) or their environmental features (SS-Env) (see Fig. 2 for larger resulting heatmap and labels). (C) Membrane protein families and environmental features network (PEN) construction. Quantification of relationships between environmental features and membrane protein families by construction of Env-Fam networks from structural correlation coefficient plots.