High level expression of transfected G protein αi3 subunit is required for plasma membrane targeting and adenylyl cyclase inhibition in NIH 3T3 fibroblasts

Sylvie Hermouet, Philippe de Mazancourt, Allen M. Spiegel, Marilyn Gist Farquhar, Bridget S. Wilson

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

The α subunits of pertussis toxin-sensitive G proteins Gi1, Gi2 and Gi3 have been shown to inhibit adenylyl cyclase in transfected cells. However, Gi3 has recently been associated with protein transport and localized to the Golgi apparatus in a number of cell lines, rather than to the plasma membrane. We studied NIH 3T3 clones stably expressing different levels of a constitutively activated mutant of the α subunit of Gi3i3-Q204L). Transfected αi3 subunits were localized to the Golgi apparatus in all NIH 3T3 clones. In clones expressing αi3-Q204L at high levels, αi3 subunits were also localized to the plasma membrane. Those clones which demonstrated expression of αi3 at the plasma membrane showed a 40% to 60% inhibition of forskolin-induced cAMP accumulation. Transfected NIH 3T3 clones in which plasma membrane αi3 was undetectable, did not show inhibition of forskolin-induced cAMP accumulation. These data suggest that, unless high expression is achieved in transfected cells, αi3 is targeted predominantly to the Golgi, not to the plasma membrane, and does not control adenylyl cyclase activity in NIH 3T3 fibroblasts.

Original languageEnglish (US)
Pages (from-to)223-228
Number of pages6
JournalFEBS Letters
Volume312
Issue number2-3
DOIs
StatePublished - Nov 9 1992
Externally publishedYes

Keywords

  • Adenylyl cyclase
  • Fibroblasts
  • Golgi
  • Gα (G proteins)

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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