Homology network of PLP-dependent enzymes. Nodes represent Hidden Markov models (HMMs) of PLP-dependent families. Edges represent homology connections (E < 10-5) between families established by HMM-HMM comparisons . Black edges connect protein families with the most significant similarities (E < 10-50). The network is visualized with the "Degree sorted circle layout" of Cytoscape . Colors were mapped into nodes using the structural group of the protein family as a node property.