Spectral analysis of protein-protein interactions in Drosophila melanogaster

Within a case study on the protein-protein interaction network (PIN) of Drosophila melanogaster we investigate the relation between the network's spectral properties and its structural features. The frequencies of loops of any size within the network can be derived from the spectrum; also the prevalence of specific subgraphs as a result of the network's evolutionary history affects its spectrum. The discrete part of the spectral density shows fingerprints of the PIN's topological features including a preference for loop structures. Duplicate nodes are also characteristic for PINs and we discuss their representation in the PIN's spectrum as well as their biological implications.