Galpha subunit Gpa2 recruits kelch repeat subunits that inhibit receptor-G protein coupling during cAMP-induced dimorphic transitions in Saccharomyces cerevisiae.

Published

Journal Article

All eukaryotic cells sense extracellular stimuli and activate intracellular signaling cascades via G protein-coupled receptors (GPCR) and associated heterotrimeric G proteins. The Saccharomyces cerevisiae GPCR Gpr1 and associated Galpha subunit Gpa2 sense extracellular carbon sources (including glucose) to govern filamentous growth. In contrast to conventional Galpha subunits, Gpa2 forms an atypical G protein complex with the kelch repeat Gbeta mimic proteins Gpb1 and Gpb2. Gpb1/2 negatively regulate cAMP signaling by inhibiting Gpa2 and an as yet unidentified target. Here we show that Gpa2 requires lipid modifications of its N-terminus for membrane localization but association with the Gpr1 receptor or Gpb1/2 subunits is dispensable for membrane targeting. Instead, Gpa2 promotes membrane localization of its associated Gbeta mimic subunit Gpb2. We also show that the Gpa2 N-terminus binds both to Gpb2 and to the C-terminal tail of the Gpr1 receptor and that Gpb1/2 binding interferes with Gpr1 receptor coupling to Gpa2. Our studies invoke novel mechanisms involving GPCR-G protein modules that may be conserved in multicellular eukaryotes.

Full Text

Duke Authors

Cited Authors

  • Harashima, T; Heitman, J

Published Date

  • October 2005

Published In

Volume / Issue

  • 16 / 10

Start / End Page

  • 4557 - 4571

PubMed ID

  • 16030250

Pubmed Central ID

  • 16030250

International Standard Serial Number (ISSN)

  • 1059-1524

Digital Object Identifier (DOI)

  • 10.1091/mbc.e05-05-0403

Language

  • eng

Conference Location

  • United States