Abstract
In the analysis of Protein-Protein Interaction (PPI) network, one intriguing problem is the reason for centrality-lethality rule. To discover the relationship between topological properties and functional features of proteins in PPI network, we classified hub proteins into two types: essential hub and nonessential hub and combined proteins' topological structure and evolutionary rate information together. We found that essential hub proteins tend to be intra-modular hubs and they had higher evolutionary conservation, nonessential hub proteins tend to be inter-modular hubs and they had lower evolutionary conservation.