title: Lipid modifications of G protein subunits. Myristoylation of Go alpha increases its affinity for beta gamma.
abstract: Myristoylated recombinant proteins can be synthesized in Escherichia coli by concurrent expression of the enzyme myristoyl-CoA:protein N-myristoyl-transferase with its protein substrates (Duronio, R.J., Jackson-Machelski, E., Heuckeroth, R.O., Olins, P. O., Devine, C.S., Yonemoto, W., Slice, L. W., Taylor, S. S., and Gordon, J. I. (1990) Proc. Natl. Acad. Sci. U. S.A. 87, 1506-1510). Expression of the G protein subunit Go alpha in this system results in the synthesis of two forms of the protein; these were separated on a column of heptylamine-Sepharose. Purification of the more abundant form of Go alpha yielded a product that has a blocked amino terminus. Chemical analysis of the fatty acids released by acid hydrolysis of the protein revealed myristic acid. The second form of the protein was not myristoylated. Myristoylated and nonmyristoylated recombinant Go alpha were compared with brain Go alpha (which is myristoylated) for their ability to interact with G protein beta gamma subunits. The nonmyristoylated recombinant protein clearly had a reduced affinity for beta gamma, while the myristoylated recombinant protein was indistinguishable from native Go alpha in its subunit interactions. Thus, myristoylation increases the affinity of alpha subunits for beta gamma. We propose that the function of myristoylation of G protein alpha subunits is, at least in part, to facilitate formation of the heterotrimer and the localization of alpha to the plasma membrane.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235.
authors.forename: M E
authors.initials: ME
authors.lastname: Linder
authors.forename: I H
authors.initials: IH
authors.lastname: Pang
authors.forename: R J
authors.initials: RJ
authors.lastname: Duronio
authors.forename: J I
authors.initials: JI
authors.lastname: Gordon
authors.forename: P C
authors.initials: PC
authors.lastname: Sternweis
authors.forename: A G
authors.initials: AG
authors.lastname: Gilman
mesh_terms: D000215:Acylation; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D004926:Escherichia coli; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D046911:Macromolecular Substances; D008970:Molecular Weight; D009226:Myristates / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000276:immunology
chemical_list: D046911:Macromolecular Substances; D009226:Myristates; D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D019204:GTP-Binding Proteins