PMID: 2120237Oct 25, 1990Paper

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

The Journal of Biological Chemistry
I H Pang, P C Sternweis

Abstract

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

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