Multiple small molecular weight GTP-binding proteins in bovine brain cytosol. Purification and characterization of a 24KDa protein.
We have separated multiple small Mr GTP-binding proteins (G-proteins) from bovine brain crude membranes, purified a novel 24KDa G protein (smg p25A) to near homogeneity and characterized it. In this paper, we have studied these small Mr G proteins in the cytosol fraction of bovine brain. [35S]GTP gamma S-binding activity is detected in the cytosol fraction but this activity is one-sixth to one-eighth of that of the crude membrane fraction. When G proteins in the cytosol fraction are purified by successive chromatographies on DEAE-cellulose, Ultrogel AcA-44, hydroxyapatite and Mono Q HR5/5 columns, multiple small Mr G proteins are separated. One of these G proteins shows a Mr of about 24KDa. Its physical, immunological and kinetic properties are indistinguishable from smg p25A. These results indicate that there are also multiple small Mr G proteins in the cytosol fraction of bovine brain, and suggest that one of the cytosol G proteins is the soluble form of smg p25A.
D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000032:analysis*; D008970:Molecular Weight
D019204:GTP-Binding Proteins