Purification and characterization of a novel GTP-binding protein with a Mr value of 24,000 from rat liver.
About 15% of the total GTP-binding proteins (G proteins) of rat liver homogenate was found in the microsomes-Golgi complex fraction. From this fraction, we purified to near homogeneity and characterized a G protein with a Mr value of 24,000 (24K G). 24K G specifically bound guanosine 5'-(3-Q-thio) triphosphate (GTP gamma S), GTP and GDP with a Kd value for GTP gamma S of about 30 nM. 24K G bound maximally about 0.7 mol of GTP gamma S/mol of protein. 24K G hydrolyzed GTP to liberate Pi with a turnover number of about 0.008 min-1. 24K G was not copurified with the beta gamma subunit of heterotrimeric G proteins. The partial amino acid sequences of 24K G revealed that this protein was a novel small G protein.
Ohmori
T
T
Department of Surgery, Kobe University School of Medicine, Japan.
Takeyama
Y
Y
Ueda
T
T
Hiroyoshi
M
M
Nakanishi
H
H
Ohyanagi
H
H
Saitoh
Y
Y
Takai
Y
Y
D000818:Animals; D002458:Cell Fractionation; D002845:Chromatography; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D017886:Durapatite; D019204:GTP-Binding Proteins / Q000302:isolation & purification* / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006150:Guanine Nucleotides / Q000378:metabolism*; D006882:Hydroxyapatites; D008099:Liver / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains
D006150:Guanine Nucleotides; D006882:Hydroxyapatites; D017886:Durapatite; D019204:GTP-Binding Proteins