A reevaluation of the role of the heterotrimeric G protein in coupling light responses in Arabidopsis

Plant Physiol. 2003 Apr;131(4):1623-7. doi: 10.1104/pp.102.017624.


Previous studies implicated the involvement of a heterotrimeric G protein in red (R) and far-red (FR) light signal transduction, but these studies utilized pharmacological or gain-of-function approaches and, therefore, are indirect tests. Here, we reexamine the role of the single canonical heterotrimeric G protein in R and FR control of hypocotyl growth using a loss-of-function approach. Single- and double-null mutants for the GPA1, AGB1 genes encoding the alpha and beta subunit of the heterotrimeric G protein, respectively, have wild-type sensitivity to R and FR. Ectopic overexpression of wild type and a constitutive active form of the alpha subunit and of the wild-type beta subunit had no effect that can be unequivocally attributed to altered R and FR responsiveness. These results preclude a direct role for the heterotrimeric G complex in R and FR transduction in Arabidopsis leading to growth control in the hypocotyl.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis / radiation effects*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • GTP-Binding Protein alpha Subunits*
  • GTP-Binding Protein beta Subunits*
  • Gene Expression Regulation, Plant
  • Heterotrimeric GTP-Binding Proteins / genetics
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • Infrared Rays
  • Light*
  • Mutation
  • Phenotype
  • Signal Transduction*


  • AGB1 protein, Arabidopsis
  • Arabidopsis Proteins
  • GPA1 protein, Arabidopsis
  • GTP-Binding Protein alpha Subunits
  • GTP-Binding Protein beta Subunits
  • Heterotrimeric GTP-Binding Proteins