title: Characterization of GFR, a novel guanine nucleotide exchange factor for Rap1.
abstract: Three groups of Rap1-specific guanine nucleotide exchange factors including C3G, CalDAG-GEFI, and Epac/cAMP-GEFI/II have been identified to date. In the present study, we report a new Rap1 guanine nucleotide exchange factor which we have named GFR (guanine nucleotide exchange factor for Rap1). GFR shows close sequence similarity to EPAC/cAMP-GEFI/II although GFR lacks a cAMP binding domain and contains a nuclear localization signal. We demonstrated that GFR can activate Rap1 but not H-Ras in 293T cells and that the cdc25 domain of GFR is required for the activation of Rap1. Northern blot analysis suggested that GFR mRNA is strongly expressed in the brain. In transfected HeLa cells, GFR has been found to be localized in the nuclei.
authors.affiliation: Department of Internal Medicine (3), Jikei University, School of Medicine, Tokyo, Japan. ichiba@jikei.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Ichiba
authors.forename: Y
authors.initials: Y
authors.lastname: Hoshi
authors.forename: Y
authors.initials: Y
authors.lastname: Eto
authors.forename: N
authors.initials: N
authors.lastname: Tajima
authors.forename: Y
authors.initials: Y
authors.lastname: Kuraishi
mesh_terms: D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014162:Transfection; D020668:rap GTP-Binding Proteins; D020663:ras Guanine Nucleotide Exchange Factors; D020666:ras-GRF1
chemical_list: D018797:Cell Cycle Proteins; D020662:Guanine Nucleotide Exchange Factors; D006150:Guanine Nucleotides; D011506:Proteins; C116122:RAPGEF3 protein, human; D012333:RNA, Messenger; D020663:ras Guanine Nucleotide Exchange Factors; D020666:ras-GRF1; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins