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Characterization of GFR, a novel guanine nucleotide exchange factor for Rap1
Author(s) -
Ichiba Tamotsu,
Hoshi Yasutaka,
Eto Yoshikatsu,
Tajima Naoko,
Kuraishi Yasunobu
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01012-1
Subject(s) - rap1 , guanine nucleotide exchange factor , guanine , gtp' , transfection , nucleotide , microbiology and biotechnology , chemistry , signal transduction , gene , biology , biochemistry , enzyme
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 ( uanine nucleotide exchange actor for ap1). 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.