Tapash Chandra Ghosh, Sandip Chakraborty, Bratati Kahali
Bioinformatics Centre, Bose Institute, P 1/12, C.I.T. Scheme VII M, Kolkata 700 054, India.


Evolutionary rates of proteins in a protein-protein interaction network are primarily governed by the protein connectivity and/or expression level as illustrated till date. A recent study portrays the importance of the features of the interacting partners, namely, the coefficient of functionality and clustering coefficient in controlling the protein evolutionary rates in a protein-protein interaction network. By multivariate regression analysis we found that the three parameters: probability of complex formation, expression level and degree of a protein independently guide the evolutionary rates of proteins in the protein-protein interaction network. The first principal component accounts for 43% of the total variation and it is mainly contributed by complex forming property of a protein and the expression level of gene. We also found that for complex forming proteins in the network, those which have partners sharing the same functional class evolve faster than those having partners belonging to different functional classes (P = 1.1×10-2 ). The former group also has lower connectivity and expression level. The proteins in the dense parts of the network evolve faster than their sparse parts counterparts (P = 7.8×10-5 ). Taking into account the complex forming ability, we found that all the complex forming proteins considered in this study evolve slowly than the non complex forming proteins (P = 1.47×10-28 ) irrespective of their localization in the network or the affiliation of their partners to same/different functional classes. Biological implications of these results will be discussed. Read More …

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