Novel G proteins, Rag C and Rag D, interact with GTP-binding proteins, Rag A and Rag B.

Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Rag A/Gtr1p are G proteins and are known to be involved in the RCC1-Ran pathway. We employed the two-hybrid method using Rag A as the bait to identify proteins binding to Rag A, and we isolated two novel human G proteins, Rag C and Rag D. Rag C demonstrates homology with Rag D (81.1% identity) and with Gtr2p of Saccharomyces cerevisiae (46.1% identity), and it belongs to the Rag A subfamily of the Ras family. Rag C and Rag D contain conserved GTP-binding motifs (PM-1, -2, and -3) in their N-terminal regions. Recombinant glutathione S-transferase fusion protein of Rag C efficiently bound to both [(3)H]GTP and [(3)H]GDP. Rag A was associated with both Rag C and Rag D in their C-terminal regions where a potential leucine zipper motif and a coiled-coil structure were found. Rag C and D were associated with both the GDP and GTP forms of Rag A. Both Rag C and Rag D changed their subcellular localization, depending on the nucleotide-bound state of Rag A. In a similar way, the disruption of S. cerevisiae GTR1 resulted in a change in the localization of Gtr2p.
Mesh Terms:
Amino Acid Motifs, Amino Acid Sequence, Binding Sites, Cell Line, Cell Nucleus, Dimerization, Dose-Response Relationship, Drug, Fungal Proteins, GTP-Binding Proteins, Glutathione Transferase, Guanosine Diphosphate, Guanosine Triphosphate, Hela Cells, Humans, Immunoblotting, Leucine, Microscopy, Fluorescence, Models, Genetic, Molecular Sequence Data, Monomeric GTP-Binding Proteins, Nucleotides, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Recombinant Fusion Proteins, Recombinant Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, Time Factors, Transfection, Two-Hybrid System Techniques, beta-Galactosidase
J. Biol. Chem. Mar. 09, 2001; 276(10);7246-57 [PUBMED:11073942]
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