Myristoylation of an inhibitory GTP-binding protein α subunit is essential for its membrane attachment

T. L.Z. Jones, W. F. Simonds, J. J. Merendino, M. R. Brann, A. M. Spiegel

Research output: Contribution to journalArticle

162 Scopus citations

Abstract

We transfected COS cells with cDNAs for the α subunit of stimulatory and inhibitory GTP-binding proteins, α(s) and α(i1), respectively, and immunoprecipitated the metabolically labeled products with specific peptide antibodies. Cells were separated into particulate and soluble fractions before immunoprecipitation; [35S]methionine-labeled α(s) and α(i) were both found primarily in the particulate fraction. [3H]Myristate was incorporated into endogenous and transfected α(i) but could not be detected in α(s) even when it was overexpressed. We converted the second residue, glycine, of α(i1) into alanine by site-directed mutagenesis. Upon transfection of the mutant α(i1) into COS cells, the [35S]methionine-labeled product was localized primarily to the soluble fraction, and, also unlike normal α(i1) , the mutant failed to incorporate [3H]myristate. The unmyristoylated mutant α(i1) could still interact with the β-γ complex, since purified βγ subunits promoted pertussis toxin-catalyzed ADP-ribosylation of both the normal and mutant α(i1) subunits. These results indicate that myristoylation is critical for membrane attachment of α(i) but not α(s) subunits.

Original languageEnglish (US)
Pages (from-to)568-572
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number2
DOIs
StatePublished - 1990
Externally publishedYes

Keywords

  • immunoprecipitation
  • signal transduction
  • site-directed mutagenesis
  • β-γ subunits

ASJC Scopus subject areas

  • General

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