Construction and analysis of human phosphorylation network

Phosphorylation controls the dynamic behavior and decision processes of eukaryotic cells. So far, thousands of phosphorylation sites have been discovered by proteome-wide mapping and other biochemical studies. In this study, we constructed a human phosphorylation network by using an integrated dataset of experimentally and computationally identified protein kinase-substrate information based on Phospho. ELM database. We performed topological analysis and component analysis for this network. Topological analysis showed distinct properties of this network such as scale-free, small-world, nonrandom and non-uniform. The component analysis identified that the protein kinase DNA-PK has the most substrates. We also found that its 718 substrates were significantly related to different cancers such as breast cancer, etc., by function annotation using DAVID bioinformatics resources. These results suggest that study on human phosphorylation network may contribute to better understanding of the function of protein kinases and their implication in diseases.