Purification and characterization from rat liver cytosol of a GDP dissociation inhibitor (GDI) for liver 24K G, a ras p21-like GTP-binding protein, with properties similar to those of smg p25A GDI

Biochemistry. 1991 Jan 29;30(4):909-17. doi: 10.1021/bi00218a005.


A regulatory protein for a liver GTP-binding protein (G protein) with a molecular weight value of 24,000 (24K G), which we have recently purified, was purified to near-homogeneity from rat liver cytosol and characterized. This regulatory protein, designated here as GDP dissociation inhibitor for 24K G (24K G GDI), inhibited the dissociation of GDP from and the subsequent binding of GTP to 24K G. 24K G GDI was inactive for other ras p21/ras p21-like small G proteins including c-Ha-ras p21, rhoB p20, smg p21B, and smg p25A. 24K G was, however, recognized by bovine brain smg p25A GDI which regulated the GDP/GTP exchange reaction of smg p25A. By analyses of sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), immunoblotting with anti-smg p25A GDI antibody, two-dimensional PAGE, and C4 column chromatography, 24K G GDI showed physical properties very similar to those of smg p25A GDI. The peptide map and the partial amino acid sequences of 24K G GDI were not identical with those of smg p25A GDI. Among the 83 residues, 2 amino acids were different between rat liver 24K G GDI and bovine brain smg p25A GDI. These results indicate that there is a specific regulatory protein for 24K G, 24K G GDI, in rat liver cytosol and that 24K G GDI has close similarity to smg p25A GDI.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Anion Exchange Resins
  • Brain Chemistry
  • Cattle
  • Centrifugation, Density Gradient
  • Chromatography
  • Cytosol / metabolism
  • Electrophoresis, Gel, Two-Dimensional
  • Electrophoresis, Polyacrylamide Gel
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / isolation & purification*
  • GTP-Binding Proteins / metabolism*
  • Guanine Nucleotide Dissociation Inhibitors*
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • Guanosine Diphosphate / metabolism
  • Liver / metabolism*
  • Male
  • Molecular Sequence Data
  • Molecular Weight
  • Peptide Mapping
  • Proto-Oncogene Proteins p21(ras) / chemistry
  • Rats
  • Rats, Inbred Strains
  • Resins, Synthetic
  • rab3 GTP-Binding Proteins
  • rap GTP-Binding Proteins
  • rho-Specific Guanine Nucleotide Dissociation Inhibitors


  • Anion Exchange Resins
  • Guanine Nucleotide Dissociation Inhibitors
  • Resins, Synthetic
  • rho-Specific Guanine Nucleotide Dissociation Inhibitors
  • Guanosine Diphosphate
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Mono Q
  • GTP-Binding Proteins
  • Proto-Oncogene Proteins p21(ras)
  • rab3 GTP-Binding Proteins
  • rap GTP-Binding Proteins