Rnd Proteins: A New Family of Rho-Related Proteins That Interfere with the Assembly of Filamentous Actin Structures and Cell Adhesion
Rho family proteins control actin organization. The Rnd proteins form a distinct branch of the Rho family: Rnd1 is expressed mostly in brain and liver, Rnd2 is highly expressed in testis and Rnd3 shows a ubiquitous, very low expression. In brain, Rnd1 is found in specialized neurons, mainly in the cortex, hippocampus and substantia nigra. Rnd1 exchanges GTP rapidly, has a low affinity for GDP, and lacks intrinsic GTPase activity, suggesting that in the cell it is constitutively in the GTP-bound form. Expression of Rnd1 in Swiss 3T3 fibroblasts inhibits the formation of actin stress fibers and induces a loss of focal adhesions and cell/cell contacts, leading to cell rounding (hence Rnd for “round”). In Swiss 3T3 fibroblasts and MDCK cells, Rnd1 localizes to adherens junctions. Thus, Rnd proteins are involved in rearrangements of the actin cytoskeleton and changes in cell adhesion that might play essential roles in cell migration and tumor invasion.
KeywordsCodon Retina Serine Proline Glutamine
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