Direct Interaction of the Rho GDP Dissociation Inhibitor with Ezrin/Radixin/Moesin Initiates the Activation of the Rho Small G Protein

• DOI: 10.1074/jbc.272.37.23371
• Publication Date: 2002-07-26T15:13:47Z
• Authors: Kazuo Takahashi; Takuya Sasaki; Akiko Mammoto; Kenji Takaishi; Takaaki Kameyama; Sachiko Tsukita; Shoichiro Tsukita; Yoshimi Takai
• Keywords: rho GTP-Binding Proteins; 0301 basic medicine; Recombinant Fusion Proteins; rab3 GTP-Binding Proteins; Microfilament Proteins; Membrane Proteins; Proteins; Blood Proteins; Phosphoproteins; Actins; Peptide Fragments; Cytoskeletal Proteins; 03 medical and health sciences; Hyaluronan Receptors; GTP-Binding Proteins; rho-Specific Guanine Nucleotide Dissociation Inhibitors; Cytoskeleton; Guanine Nucleotide Dissociation Inhibitors; Protein Binding

The Rho GDP dissociation inhibitor (GDI) forms a complex with the GDP-bound form of the Rho family small G proteins and inhibits their activation. The GDP-bound form complexed with Rho GDI is not activated by the GDP/GTP exchange factor for the Rho family members, suggesting the presence of another factor necessary for this activation. We have reported that the Rho subfamily members regulate the ezrin/radixin/moesin (ERM)-CD44 system, implicated in reorganization of actin filaments. Here we report that Rho GDI directly interacts with ERM, initiating the activation of the Rho subfamily members by reducing the Rho GDI activity. These results suggest that ERM as well as Rho GDI and the Rho GDP/GTP exchange factor are involved in the activation of the Rho subfamily members, which then regulate reorganization of actin filaments through the ERM system.