Figure 1
From: Detection of gene orthology from gene co-expression and protein interaction networks
Graph-based ortholog representation A schematic of the graph representation of the BLAST orthologs based on protein-protein interaction networks and gene coexpression networks. The networks are represented as two labeled graphs (G1 and G2) with corresponding relationships among their nodes (similarly colored nodes are sequence homologous according to a BLAST search). Nodes from G1 (e.g., v3) are compared to their sequence-homologous counterparts in G2 (e.g., v'2 and v'6) based on the topology of their neighborhood and sequence homology of the neighbors. In the figure, v'2 has the same number of neighbors of v3 and one of the neighbors of v'2 (i.e., v'3) is sequence-homologous to v4. Thus, v'2 is scored higher (more likely to be an ortholog to v3) compared to v'6. Protein-protein interaction networks are represented as unweighted graphs, while gene coexpression networks incorporate weights (as calculated by correlations) into their edges.