Ras homology family 4 (Rho4) of small guanosine triphosphatases (GTPases)-like
Rho4 is a GTPase that controls septum degradation by regulating secretion of Eng1 or Agn1 during cytokinesis. Rho4 also plays a role in cell morphogenesis. Rho4 regulates septation and cell morphology by controlling the actin cytoskeleton and cytoplasmic microtubules. The localization of Rho4 is modulated by Rdi1, which may function as a GDI, and by Rga9, which is believed to function as a GAP. In S. pombe, both Rho4 deletion and Rho4 overexpression result in a defective cell wall, suggesting a role for Rho4 in maintaining cell wall integrity. 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.