Ras-interacting domain of RGL blocks Ras-dependent signal transduction in Xenopus oocytes.
RalGDS family members (ralGDS and RGL) interact with the GTP-bound form of Ras through its effector loop. The C-terminal region (amino acids 602-768) of RGL is responsible for binding to Ras. In this paper we characterized a Ras-interacting domain of RGL using deletion mutants of RGL(602-768). RGL(602-768), RGL(632-768), and RGL (602-734) bound to the GTP-bound form of Ras and inhibited the GAP activity of NF-1. RGL(646-768) showed a low binding activity to Ras and inhibited GAP activity of NF-1 weakly. None of RGL(659-768), RGL(685-768), RGL(602-709), and RGL(602-686) bound to Ras or inhibited GAP activity of NF-1. These results indicate that amino acids 632-734 of RGL constitute a nearly minimal domain that contains the binding element for Ras. RGL(632-734) inhibited v-Ras- but not progesterone-induced Xenopus oocyte maturation. Furthermore, RGL(632-734) inhibited v-Ras- but not v-Raf- dependent extracellular signal-regulated kinase activation in Xenopus oocytes. These results clearly demonstrate that the Ras-interacting domain of RGL is important for Ras-dependent signal transduction in vivo.
Koyama
S
S
Department of Biochemistry, Hiroshima University School of Medicine, Japan.
Chen
Y W
YW
Ikeda
M
M
Muslin
A J
AJ
Williams
L T
LT
Kikuchi
A
A
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D006160:Guanosine Triphosphate / Q000378:metabolism; D025542:Neurofibromin 1; D009865:Oocytes / Q000502:physiology; D010446:Peptide Fragments; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D017384:Sequence Deletion; D015398:Signal Transduction / Q000502:physiology*; D014981:Xenopus; D020703:ras GTPase-Activating Proteins; D018631:ras Proteins / Q000378:metabolism / Q000502:physiology*
D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D025542:Neurofibromin 1; D010446:Peptide Fragments; D011506:Proteins; D011993:Recombinant Fusion Proteins; D020703:ras GTPase-Activating Proteins; D006160:Guanosine Triphosphate; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D018631:ras Proteins