CHARACTERIZATION OF 4 G-0-TYPE PROTEINS PURIFIED FROM BOVINE BRAIN MEMBRANES

Recently we reported there were at least four types of GO or GO-like proteins in bovine brain membranes based on their elution profiles from Mono Q columns and their immunological reactivities; one of the proteins was purified as an α-monomeric form, and the others as αβγ-trimers. The four proteins, of which α-subunits were confirmed to be a family of GO-type by an immunoblot analysis, were thus referred toas αO1, GO2, GO3 and GO4, respectively, in order of their elutions from the column. Immunostained peptide mappings arising from proteolytic digestions of the four α-subunits, together with their fragmentation patterns containing radiolabeled ADP-ribose that had been incorporated by pertussis toxin-catalyzed ADP-ribosylation, suggested that the four GO-α were classified into either of two groups such as α1 and GO2-α or GO3-α and GO4-α. The kinetic parameters of their GTPase activities, however, revealed that there were different properties between αO1 and GO2-α or GO3-α and GO4-α. Thus, the four GO-type proteins appeared to be different entities from one another. © 1990.