Rabbit intestine contains a protein that inhibits the dissociation of GDP from and the subsequent binding of GTP to rhoB p20, a ras p21-like GTP-binding protein.
A novel regulatory protein for rhoB p20, a ras p21-like GTP-binding protein (G protein), was partially purified from the cytosol fraction of rabbit intestine. This protein, designated as rhoB p20 GDP dissociation inhibitor (GDI), inhibited the dissociation of GDP from rhoB p20. rhoB p20 GDI also inhibited the binding of guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) to the GDP-bound form of rhoB p20 but not of that to the guanine nucleotide-free form. GDI did not affect the GTPase activity of rhoB p20 and by itself showed no GTP gamma S-binding activity. GDI was inactive for other ras p21/ras p21-like G proteins including c-Ha-ras p21, smg p21 and smg p25A. The Mr value of GDI was estimated to be about 27,000 from the S value. These results indicate that rabbit intestine contains a novel regulatory protein that inhibits the dissociation of GDP from and thereby the subsequent binding of GTP to rhoB p20.
Ohga
N
N
Department of Biochemistry, Kobe University School of Medicine, Japan.
Kikuchi
A
A
Ueda
T
T
Yamamoto
J
J
Takai
Y
Y
D000818:Animals; D002499:Centrifugation, Density Gradient; D002852:Chromatography, Ion Exchange; D003600:Cytosol / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000302:isolation & purification* / Q000378:metabolism*; D020730:Guanine Nucleotide Dissociation Inhibitors; D006150:Guanine Nucleotides / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D011817:Rabbits; D013873:Thionucleotides / Q000378:metabolism; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020743:rhoB GTP-Binding Protein
D020730:Guanine Nucleotide Dissociation Inhibitors; D006150:Guanine Nucleotides; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D013873:Thionucleotides; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras); D020743:rhoB GTP-Binding Protein