In this work, we show that this model can be used to fit experimental data on the PIN of yeast Saccharomyces cerevisae at two different time instances simultaneously. Our study shows that the evolution of PIN given by model is consistent with growing experimental data over time, and that the scale-free property of protein interaction network is robust against random deletion of interactions. | Communications in Physics, Vol. 22, No. 1 (2012), pp. 7-14 EVOLUTION OF PROTEIN-PROTEIN INTERACTION NETWORKS IN DUPLICATION-DIVERGENCE MODEL BUI PHUONG THUY Nam Dinh University of Technology Education TRINH XUAN HOANG Institute of Physics, VAST Abstract. Protein interacts with one another resulting in complex functions in living organisms. Like many other real-world networks, the networks of protein-protein interactions possess a certain degree of ordering, such as the scale-free property. The latter means that the probability P to find a protein that interacts with k other proteins follows a power law, P (k) ∼ k−γ . Protein interaction networks (PINs) have been studied by using a stochastic model, the duplication-divergence model, which is based on mechanisms of gene duplication and divergence during evolution. In this work, we show that this model can be used to fit experimental data on the PIN of yeast Saccharomyces cerevisae at two different time instances simultaneously. Our study shows that the evolution of PIN given by model is consistent with growing experimental data over time, and that the scale-free property of protein interaction network is robust against random deletion of interactions. I. INTRODUCTION Proteins are molecules that play crucial roles in almost every biological processes [1]. Their functions include catalysis, transport of ions, cell signaling, and activity in the immune system. Many diseases are found because of a disorder in processing of proteins or a lack of activity by a certain protein. For example, type I diabetes is known to be related to the inability of the pancreas to produce enough insulin to properly control blood sugar levels, whereas type II diabetes is due to a lack of proper function of insulins – or insulin resistance. The functionality of a protein pertains to its three-dimensional structure. Protein structures can be measured experimentally by NMR or X-ray crystallography, and to some extents, at least, can be .
