Open AccessPurification of a factor capable of stimulating the guanine nucleotide exchange reaction of ras proteins and its effect on ras-related small molecular mass G proteins.
Author(s) -
Ying Huang,
HsiangFu Kung,
Tohru Kamata
Publication year - 1990
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.87.20.8008
Subject(s) - guanosine diphosphate , guanine nucleotide exchange factor , guanine , gtp' , molecular mass , g protein , gtp binding protein regulators , biochemistry , chemistry , nucleotide , fast protein liquid chromatography , gtpase activating protein , guanosine , hras , polyacrylamide gel electrophoresis , gel electrophoresis , adp ribosylation factor , gtpase , signal transduction , enzyme , gene , mutation , golgi apparatus , cell , kras
We have previously identified a membrane factor capable of stimulating guanine nucleotide exchange activity for ras p21 proteins. The ras guanine nucleotide exchange factor (rGEF) was purified from bovine brain to near homogeneity by successive chromatographies on DE52 DEAE-cellulose, Sepharose 6B, hydroxylapatite, and FPLC phenyl-Superose resins. SDS/polyacrylamide gel electrophoresis of the purified rGEF showed a single major protein with a molecular mass of 35 kDa. rGEF increased the exchange rate of GDP in normal [Gly12]p21 or oncogenic [Val12]p21 up to 30- to 40-fold under physiological concentrations of Mg2+. Since the factor was free from GDP/GTP binding activity and nonspecific GDP hydrolytic activity, we propose that rGEF may regulate GDP/GTP exchange reaction of ras proteins in response to external growth signals. Moreover, rGEF enhanced the dissociation of bound GDP from some of ras-like G proteins, R-ras, rap1-A, rab1-B, and rho proteins, raising the possibility that rGEF may affect the activities of these proteins.