The G protein β subunit is essential for multiple responses to chemoattractants in Dictyostelium

Lijun Wu, Romi Valkema, Peter J M Van Haastert, Peter N Devreotes

Research output: Contribution to journalArticle

Abstract

Increasing evidence suggests that the βγ-subunit dimers of heterotrimeric G proteins play a pivotal role in transducing extracellular signals. The recent construction of Gβ null mutants (gβ-) in Dictyostelium provides a unique opportunity to study the role of dimers in signaling processes mediated by chemoattractant receptors. We have shown previously that gβ- cells fail to aggregate; in this study, we report the detailed characterization of these cells. The gβ- cells display normal motility but do not move towards chemoattractants. The typical GTP-regulated high affinity chemoattractant-binding sites are lost in gβ- cells and membranes. The gβ- cells do not display chemoattractant-stimulated adenylyl cyclase or guanylyl cyclase activity. These results show that in vivo Gβ links chemoattractant receptors to effectors and is therefore essential in many chemoattractant-mediated processes. In addition, we find that Gβ is required for GTPγS stimulation of adenylyl cyclase activity, suggesting that the βγ-dimer activates the enzyme directly. Interestingly, the gβ- cells grow at the same rate as wild-type cells in axenic medium but grow more slowly on bacterial lawns and, therefore, may be defective in phagocytosis.

Original languageEnglish (US)
Pages (from-to)1667-1675
Number of pages9
JournalJournal of Cell Biology
Volume129
Issue number6
DOIs
Publication statusPublished - Jun 1995

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ASJC Scopus subject areas

  • Cell Biology

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