Isolation of a novel G-protein gamma-subunit from Arabidopsis thaliana and its interaction with Gbeta

Biochim Biophys Acta. 2001 Aug 30;1520(2):147-53. doi: 10.1016/s0167-4781(01)00262-7.


There is increasing evidence that heterotrimeric G-proteins (G-proteins) are involved in many plant processes including phytohormone response, pathogen defence and stomatal control. In animal systems, each of the three G-protein subunits belong to large multigene families; however, few subunits have been isolated from plants. Here we report the cloning of a second plant G-protein gamma-subunit (AGG2) from Arabidopsis thaliana. The predicted AGG2 protein sequence shows 48% identity to the first identified Arabidopsis Ggamma-subunit, AGG1. Furthermore, AGG2 contains all of the conserved characteristics of gamma-subunits including a small size (100 amino acids, 11.1 kDa), C-terminal CAAX box and a N-terminal alpha-helix region capable of forming a coiled-coil interaction with the beta-subunit. A strong interaction between AGG2 and both the tobacco (TGB1) and Arabidopsis (AGB1) beta-subunits was observed in vivo using the yeast two-hybrid system. The strong association between AGG2 and AGB1 was confirmed in vitro. Southern and Northern analyses showed that AGG2 is a single copy gene in Arabidopsis producing two transcripts that are present in all tissues tested. The isolation of a second gamma-subunit from A. thaliana indicates that plant G-proteins, like their mammalian counterparts, may form different heterotrimer combinations that presumably regulate multiple signal transduction pathways.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / chemistry*
  • Arabidopsis / genetics
  • Arabidopsis Proteins / chemistry*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / isolation & purification
  • Cloning, Molecular
  • DNA, Complementary / biosynthesis
  • DNA, Complementary / chemistry
  • GTP-Binding Protein gamma Subunits / chemistry*
  • GTP-Binding Protein gamma Subunits / genetics
  • GTP-Binding Protein gamma Subunits / isolation & purification
  • Gene Expression Regulation, Plant
  • Molecular Sequence Data
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Sequence Alignment


  • AGG2 protein, Arabidopsis
  • Arabidopsis Proteins
  • DNA, Complementary
  • GTP-Binding Protein gamma Subunits
  • Protein Isoforms

Associated data

  • GENBANK/AF347077
  • GENBANK/AF347078