RhoGDI-3 is a new GDP dissociation inhibitor (GDI). Identification of a non-cytosolic GDI protein interacting with the small GTP-binding proteins RhoB and RhoG.
RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. We have reported that the transient expression of the endogenous RhoB protein is regulated during the cell cycle, contrasting with the permanent RhoA protein expression (). Using the yeast two-hybrid system to characterize proteins interacting with RhoB, we identified a new mouse Rho GDP dissociation inhibitor, referenced as RhoGDI-3. The NH2-terminal alpha helix of RhoGDI-3 is strongly amphipatic and differs thus from that found in previously described bovine, human, and yeast RhoGDI proteins and mouse and human D4/Ly-GDIs. Contrary to the cytosolic localization of all known GDI proteins, acting on Rab or Rho, RhoGDI-3 is associated to a Triton X-100-insoluble membranous or cytoskeletal subcellular fraction. In the two-hybrid system, RhoGDI-3 interacts specifically with GDP- and GTP-bound forms of post-translationally processed RhoB and RhoG proteins, both of which show a growth-regulated expression in mammalian cells. No interaction is found with RhoA, RhoC, or Rac1 proteins. We show that GDI-3 is able to inhibit GDP/GTP exchange of RhoB and to release GDP-bound but not GTP-bound RhoB from cell membranes.
Zalcman
G
G
Unité INSERM 248, Section de Recherche, Institut Curie, 26 rue d'Ulm, 75231 Paris Cedex 05, France.
Closson
V
V
Camonis
J
J
Honoré
N
N
Rousseau-Merck
M F
MF
Tavitian
A
A
Olofsson
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D002885:Chromosomes, Human, Pair 16; D003001:Cloning, Molecular; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020730:Guanine Nucleotide Dissociation Inhibitors; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment; D014018:Tissue Distribution; D014157:Transcription Factors / Q000378:metabolism*; D020741:rho GTP-Binding Proteins; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062950:rho Guanine Nucleotide Dissociation Inhibitor gamma; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020743:rhoB GTP-Binding Protein
C569638:ARHGDIA protein, human; C569643:ARHGDIG protein, human; C569650:Arhgdig protein, mouse; D020730:Guanine Nucleotide Dissociation Inhibitors; D008565:Membrane Proteins; D012333:RNA, Messenger; C489577:Rhog protein, mouse; D014157:Transcription Factors; D062948:rho Guanine Nucleotide Dissociation Inhibitor alpha; D062950:rho Guanine Nucleotide Dissociation Inhibitor gamma; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D006153:Guanosine Diphosphate; C075397:RHOG protein, human; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D020743:rhoB GTP-Binding Protein