Rnd3/RhoE/Rho8 subfamily. Rnd3/RhoE/Rho8 is a member of the novel Rho subfamily Rnd, together with Rnd1/Rho6 and Rnd2/Rho7. Rnd3/RhoE is known to bind the serine-threonine kinase ROCK I. Unphosphorylated Rnd3/RhoE associates primarily with membranes, but ROCK I-phosphorylated Rnd3/RhoE localizes in the cytosol. Phosphorylation of Rnd3/RhoE correlates with its activity in disrupting RhoA-induced stress fibers and inhibiting Ras-induced fibroblast transformation. In cells that lack stress fibers, such as macrophages and monocytes, Rnd3/RhoE induces a redistribution of actin, causing morphological changes in the cell. In addition, Rnd3/RhoE has been shown to inhibit cell cycle progression in G1 phase at a point upstream of the pRb family pocket protein checkpoint. Rnd3/RhoE has also been shown to inhibit Ras- and Raf-induced fibroblast transformation. In mammary epithelial tumor cells, Rnd3/RhoE regulates the assembly of the apical junction complex and tight junction formation. Rnd3/RhoE is underexpressed in prostate cancer cells both in vitro and in vivo; re-expression of Rnd3/RhoE suppresses cell cycle progression and increases apoptosis, suggesting it may play a role in tumor suppression. 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",