Unraveling Protein Networks with Power Graph Analysis
Figure 10
Power Graph Analysis of the Human Protein Tyrosine Phosphatase Homology Network.
(A) The original homology network has 279 nodes and 4849 edges. The power graph has 209 power edges - with the addition of 95 non-singleton power nodes. Each node represents a human protein tyrosine phosphatase, with an edge between two proteins corresponding to highly significant alignments with E-values of at most 10−46. The network is obtained by an all against all BLASTP scan using the NCBI BLASTP tool [90]. Greyed power nodes correspond to totally connected sets of proteins, for example, all receptor type protein tyrosine phosphatases have an alignment E-value of at least 10−46. Black power edges represent many edges of low E-values (lower than 10−46), light-gray power edges abstract fewer edges and correspond to less significant sequence similarities. (B) Multiple sequence alignment for type G against type 22 and type G against type 20. The similarity observed in the power graph between type G and type 22 is explained by the homology between a region of type 22 non-receptors and the second copy of the tyrosine phosphatase domain of type G receptors. Negative control: type G and type 20 - which are not linked - do not share this similar region.