Preferential attachment in the protein network evolution

TL;DR

This paper demonstrates that the evolution of the yeast protein interaction network follows a preferential attachment process, where older proteins tend to acquire more interactions, explaining its scale-free topology.

Contribution

It provides empirical evidence that preferential attachment explains the evolution of protein networks, validating the model's applicability to biological systems.

Findings

Older proteins have more interactions.

Protein interaction gains are proportional to existing connectivity.

Supports preferential attachment as a key evolutionary mechanism.

Abstract

The Saccharomyces cerevisiae protein-protein interaction map, as well as many natural and man-made networks, shares the scale-free topology. The preferential attachment model was suggested as a generic network evolution model that yields this universal topology. However, it is not clear that the model assumptions hold for the protein interaction network. Using a cross genome comparison we show that (a) the older a protein, the better connected it is, and (b) The number of interactions a protein gains during its evolution is proportional to its connectivity. Therefore, preferential attachment governs the protein network evolution. The evolutionary mechanism leading to such preference and some implications are discussed.