Sparsely Connected Hubs in Protein Networks

Abstract

Genomic and proteomic analyses, combined with accumulated knowledge of cell signaling pathways, are exposing characteristics of the regulatory networks that control physiology. In fact, there is now sufficient detail so that the properties of the networks themselves can be described and analyzed. Maslov and Sneppen examined the protein interaction network described by a systematic screen of yeast protein interactions by the two-hybrid method and also a network of yeast proteins whose regulatory interactions have been genetically defined. In both cases, a relatively small set of proteins are highly connected to other proteins, but these highly connected proteins are primarily connected to proteins with sparse connectivity, not to other proteins that are highly connected. This suppression of interaction of the highly connected nodes in the network has implications for specificity and cross talk in the signaling mechanisms. The authors note that, for reasons not yet clear, the organization of the protein networks is similar to that for interconnection of internet service providers. S. Maslov, K. Sneppen, Specificity and stability in topology of protein networks. Science 296, 910-913 (2002). [Abstract] [Full Text]