Purification of unique alpha subunits of GTP-binding regulatory proteins (G proteins) by affinity chromatography with immobilized beta gamma subunits.

摘要: Novel G protein alpha subunits were purified from rat brain by an affinity matrix containing immobilized beta gamma (Pang, I.-H., and Sternweis, P. C. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 7814-7818). They unique based on the following criteria. These migrated differently through polyacrylamide gels with apparent molecular mass of 42 kDa. did not behave similarly to other proteins conventional chromatographic techniques. Antisera raised against a common region known failed recognize these 42-kDa polypeptides. Finally, primary sequences tryptic fragments contain regions homologous to, yet from, subunits. Sequences are identical one or more members new family recently identified genetic techniques (Strathmann, M., Wilke, T. Simon, M. I. 7407-7409); most sequence identifies subunit labeled q. polypeptides substrates for ADP-ribosylation catalyzed pertussis toxin. bound GTP S only slow rates low stoichiometry. peptides specific indicate that they widely distributed at levels in different tissues but concentrated lung. This procedure provides means preparing native have potential role as modulators toxin-insensitive regulatory pathways.