Evolution of the Ras Superfamily of GTPases

Abstract

The Ras superfamily of small GTPases illustrates a large functional diversification in the context of a preserved structural framework and a prototypic GTP-binding site. The Ras superfamily of small GTP-binding proteins is essential to regulate the cellular organization and signaling in cells. Members of this superfamily contain a structurally and mechanistically preserved GTP-binding core, with considerable functional and sequence divergence. In this chapter we review the evolutionary structure of the superfamily at the organism and sequence level, presenting a representative tree that reflects the history of the Ras superfamily including crucial evolutionary time points and detailed trees for the Rho, Ras, Rab, Arf, and Ran families. Based on this information we discuss some of the complex relationships between the evolution of proteins and the acquisition of distinctive cellular functions.