Evolutionary constraints on hub and non-hub proteins in human protein interaction network: Insight from protein connectivity and intrinsic disorder

It has been claimed that proteins with more interacting partners (hubs) are structurally more disordered and have a slow evolutionary rate. Here, in this paper we analyzed the evolutionary rate and structural disorderness of human hub and non-hub proteins present/absent in protein complexes. We observed that both non-hub and hub proteins present in protein complexes, are characterized by high structural disorderness. There exists no significant difference in average evolutionary rate of complex-forming hub and non-hub proteins while we have found a significant difference in the average evolutionary rate between hub and non-hub proteins which are not present in protein complexes. We concluded that higher disorderness in complex forming non-hub proteins facilitates higher number of interactions with a large number of protein subunits. High interaction among protein subunits of complex forming non-hub proteins imposes a selective constraint on their evolutionary rate.