Differential Isoprenylation of Carboxy-Terminal Mutants of an Inhibitory G-Protein α-Subunit: Neither Farnesylation nor Geranylgeranylation Is Sufficient for Membrane Attachment

James E. Butrynski, Peter S. Backlund, Allen M. Spiegel, Teresa L.Z. Jones

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

To determine the effect of protein isoprenylation with farnesyl vs geranylgeranyl groups on membrane association in vivo, COS cells were transfected with cDNAs encoding the wild-type G-protein αil (WT) subunit, the soluble nonmyristoylated G-protein αil glycine to alanine mutant (GA), a double mutant in which the carboxy-terminal residues CGLF of GA were mutated to CVLS (GA-CVLS), and a double mutant in which the carboxy terminus of GA was mutated to CALL (GA-CALL). As opposed to the WT and GA proteins, the GA-CVLS and GA-CALL proteins were not pertussis toxin substrates nor were they recognized by antibodies that recognize the nonmutated αi1 carboxy terminus. Only the GA-CVLS and GA-CALL proteins incorporated [3H]mevalonate in the form of a farnesyl and a geranylgeranyl moiety, respectively. Subcellular localization, as assessed by immunoblotting and immunoprecipitation, revealed that the WT protein localizes almost exclusively to the membrane fraction, whereas the GA, GA-CVLS, and GA-CALL proteins localize predominantly to the soluble fraction. The soluble GA-CVLS and GA-CALL proteins were not carboxyl methylated, but the small amount localized to the membrane was partially carboxyl methylated. These results indicate that neither farnesylation nor geranylgeranylation is sufficient alone to lead to membrane association.

Original languageEnglish (US)
Pages (from-to)8030-8035
Number of pages6
JournalBiochemistry
Volume31
Issue number34
DOIs
StatePublished - Feb 1 1992
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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