Identification of Rgl3 as a potential binding partner for Rap-family small G-proteins and profilin II.
A cDNA encoding a RalGDS-related protein, Rgl3, was isolated by yeast two-hybrid screening using a small G-protein, Rap1, as a bait. Rgl3 mRNA is commonly detectable in several visceral organs (e.g. kidney, heart, liver, and lung) in the mouse and human. The Rgl3 protein mainly localizes in the cytoplasm when expressed in fibroblasts. Yeast two-hybrid assay indicated that Rgl3 could interact with Rap1, Rap2, H-Ras, N-Ras, and R-Ras but failed to interact efficiently with Ral and Rho. Interestingly, Rgl3 was found to affect cell morphology in two assay systems in culture. First, Rgl3 suppressed cell-spreading induced by Rap1, R-Ras, or C3G-CAAX (a membrane-targeted Rap/R-Ras activator) in HEK-293 cells. Second, Rgl3 enhanced the focus-formation induced by oncogenic H-Ras and N-Ras mutants in NIH3T3 cells. Moreover, we identified profilin II as a potential binding partner for Rgl3 by yeast two-hybrid screening. This interaction requires the characteristic proline cluster in the Rgl3 amino-terminal domain. Profilin II and Rgl3 co-operated in enhancing the N-Ras-induced focus-formation. These findings raise the possibility that Rgl3 mediates interaction between Ras/Rap-family proteins and profilin II, an important activator of actin polymerization.
Xu
Jiegou
J
Department of Molecular Oncology, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501 Japan.
Shi
Shuliang
S
Matsumoto
Naoya
N
Noda
Makoto
M
Kitayama
Hitoshi
H
D000595:Amino Acid Sequence; D000818:Animals; D002461:Cell Line, Transformed; D002465:Cell Movement; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D051304:Profilins / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D020726:ral Guanine Nucleotide Exchange Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D051304:Profilins; D012333:RNA, Messenger; C521670:Rgl3 protein, human; C413753:Rgl3 protein, mouse; D020726:ral Guanine Nucleotide Exchange Factor; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins