Overview of Small GTPase Signaling Proteins in Plants

Abstract

The Rho family of small GTPases is the monomeric GTP-binding protein that regulates several cellular processes, including vesicle trafficking, cell morphogenesis, mitotic spindle assembly, and gene expression in both metazoa and plants. Rho GTPase superfamily is conserved in all eukaryotic organisms. On the other hand, no clear homolog of the animal Rho GTPase protein has been identified in plants. During the course of time, plants have evolved a novel Rho subfamily, ROP (Rho in plants). The plant-specific ROP GTPases are highly similar to the animal RACs at the protein level due to which they are also referred to as RACs. ROP proteins appear to originate and undergo rapid diversification prior to the emergence of vascular plants. The ROP proteins are believed to be expanded by gene duplications and their large numbers suggest that they probably evolve to offset the deficit of Ras proteins. The ROP family of monomeric GTPases has emerged as a versatile key regulator in plant signal transduction processes.