Evolution of the G protein alpha subunit multigene family.

T. M. Wilkie, S. Yokoyama

Research output: Contribution to journalReview articlepeer-review

39 Scopus citations


G protein-mediated signal transduction systems have been identified in a diverse group of eukaryotic organisms, including yeast, plants, Dictyostelium and animals. G protein signaling components have been identified in many of these organisms, from the seven transmembrane domain receptors to distinct alpha, beta and gamma subunits of the heterotrimeric G protein and the intracellular effectors which they regulate. Their broad distribution and sequence conservation implies that genes encoding the components of G protein signaling evolved with early eukaryotes. Their subsequent proliferation among eukaryotic organisms provides an opportunity to study the coevolution of these interacting multigene families. We have focused our interests on G protein alpha subunits, which bind and hydrolyze GTP and interact with receptors and effectors. Gene structure and nucleotide sequence comparisons provided a comprehensive picture of G alpha evolution. Sequence comparisons identified three major groups of G alpha genes, termed the GPA, the G alpha-I and G alpha-II Groups. G alpha genes within the three Groups have evolved at different rates. The GPA Group is primarily composed of G alpha genes from fungi, plants, and slime mold. Within the G alpha-I and G alpha-II Groups, four classes of genes have been identified based upon sequence comparisons and functional similarities; Gi, Gq, G12, and GS. Members of all four classes are expressed in invertebrates and vertebrates but not in other eukaryotes, suggesting that this quartet evolved with metazoan progenitors.

Original languageEnglish (US)
Pages (from-to)249-270
Number of pages22
JournalSociety of General Physiologists series
StatePublished - 1994

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)


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