A distance matrix is a set of genetic distances between all possible pairs of proteins under consideration, and is used to construct a phylogenetic tree by the distance matrix method. Pazos and Valencia (2001) have developed a method to predict protein-protein interaction by evaluating the similarity of the distance matrices, under the assumption that the phylogenetic trees of interacting proteins resemble each other through co-evolution. It is known, however, that the prediction includes many false positives. We postulated that the cause of the false positives is the background similarity of the phylogenetic relationship of the source organisms. We have developed a method to exclude such information from the distance matrices with a projection operator. The number of false positives was drastically reduced from the prediction by evaluating the similarity between the residuals after the projection operation.
2007 by THE BIOPHYSICAL SOCIETY OF JAPAN