Rac 'n Rho

Snails, swiss, and serum: The solution for Rac ‘n’ Rho

Looking back can be a sobering exercise for any scientist. It is true that some important lessons are there to be learned, but most of the time breakthroughs and new paradigms come from obscure and unpredictable beginnings. The Rho GTPase story is no exception to this "rule." Rho first surfaced in 1985 when the late Pascal Madaule, working as a postdoc with Richard Axel, identified a Ras homolo...

Rac and Rho

How were they discovered? The first Rho gene was discovered by mistake, in 1985, by a group trying to clone a homologue of the α subunit of human chorionic gonadotropin from the sea snail Aplysia. Using the Aplysia Rho sequence, three closely related mammalian genes were cloned, now called RhoA, RhoB and RhoC. Rac was first identified as a substrate for the C3 transferase that modifies Rho (alt...

Rac Downregulates Rho Activity

Using biochemical assays to determine the activation state of Rho-like GTPases, we show that the guanine nucleotide exchange factor Tiam1 functions as a specific activator of Rac but not Cdc42 or Rho in NIH3T3 fibroblasts. Activation of Rac by Tiam1 induces an epithelial-like morphology with functional cadherin-based adhesions and inhibits migration of fibroblasts. This epithelial phenotype is ...

Rho and Rac Take Center Stage

Many features of cell behavior are regulated by Rho family GTPases, but the most profound effects of these proteins are on the actin cytoskeleton and it was these that first drew attention to this family of signaling proteins. Focusing on Rho and Rac, we will discuss how their effectors regulate the actin cytoskeleton. We will describe how the activity of Rho proteins is regulated downstream fr...

Rac and Rho compete to cooperate