Rnd1/Rho6 is a member of the novel Rho subfamily Rnd, together with Rnd2/Rho7 and Rnd3/RhoE/Rho8. Rnd1/Rho6 binds GTP but does not hydrolyze it to GDP, indicating that it is constitutively active. In rat, Rnd1/Rho6 is highly expressed in the cerebral cortex and hippocampus during synapse formation, and plays a role in spine formation. Rnd1/Rho6 is also expressed in the liver and in endothelial cells, and is upregulated in uterine myometrial cells during pregnancy. Like Rnd3/RhoE/Rho8, Rnd1/Rho6 is believed to function as an antagonist to RhoA. Most Rho proteins contain a lipid modification site at the C-terminus, with a typical sequence motif CaaX, where a = an aliphatic amino acid and X = any amino acid. Lipid binding is essential for membrane attachment, a key feature of most Rho proteins. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.