Isoprenylation of an inhibitory G protein α subunit occurs only upon mutagenesis of the carboxyl terminus

Teresa L.Z. Jones, Allen M. Spiegel

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


We transfected COS cells with expression vectors for the wild-type G protein αi1 subunit (pWT) and for mutated αi1 subunits, including the nonmyristylated glycine 2 to alanine mutant (pGA) and mutants in which the carboxyl termini of pWT and pGA were changed from CGLF to CVLS (pCVLS and pGA-CVLS, respectively). Immunoblot analysis of transfected COS cells with an antibody to residues 159-168 of the an protein indicated that all four proteins were expressed. Unlike the WT and GA proteins, both CVLS mutant proteins failed to react with an antibody specific for the carboxyl terminus and failed to undergo pertussis toxin-catalyzed ADP-ribosylation. Analysis of COS cell lysates after [3H]mevalonic acid labeling indicated that specific incorporation of radioactivity occurred only in the αi1 subunits with the CVLS mutation. Immunoprecipitation of COS cell fractions after labeling with [35S]methionine indicated that both WT and CVLS mutant proteins were localized predominantly in the particulate fraction, whereas GA and GA-CVLS mutant proteins were found primarily in the soluble fraction. These results directly demonstrate that the carboxyl-terminal sequence, CGLF, is incapable of leading to isoprenylation but that alteration of two residues (glycine to valine, phenylalanine to serine) is sufficient to promote isoprenylation.

Original languageEnglish (US)
Pages (from-to)19389-19392
Number of pages4
JournalJournal of Biological Chemistry
Issue number32
StatePublished - Nov 15 1990
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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