Molecular characterization of an Arabidopsis thaliana cDNA encoding a small GTP-binding protein, Rha1

Plant J. 1991 Sep;1(2):167-74.


We have isolated a cDNA encoding a small GTP-binding protein from an Arabidopsis thaliana cDNA library using an oligonucleotide probe derived from the most conserved domain of the ras superfamily. The cDNA encodes a 21.8 kDa protein, designated Rha1, which shows high homology to members of the ras superfamily in the regions involved in GTP binding, GTPase activity, and membrane attachment. The amino acid sequence is 60% identical to the sequence of the mammalian Rab5 protein, a small GTP-binding protein which is believed to be involved in endocytosis. Several regions, including the putative effector domain are completely conserved. This high percentage of amino acid identity suggests that the Rha1 protein is the functional plant counterpart of the Rab5 protein. When expressed in E. coli, the Rha1 protein was shown to bind GTP. The rha1 gene is most highly expressed in root and callus tissue, weakly expressed in stems and inflorescences and virtually not expressed in leaves and seed pods. Genomic Southern analysis revealed that rha 1 is part of a small multigene family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Arabidopsis / genetics*
  • Arabidopsis Proteins*
  • Base Sequence
  • Cloning, Molecular
  • Culture Techniques
  • DNA
  • Dogs
  • Escherichia coli
  • GTP-Binding Proteins / genetics*
  • Humans
  • Molecular Sequence Data
  • Multigene Family
  • Plant Proteins / genetics*
  • Sequence Homology, Amino Acid
  • rab GTP-Binding Proteins*
  • rab5 GTP-Binding Proteins


  • Arabidopsis Proteins
  • Plant Proteins
  • Rha1 protein, Arabidopsis
  • DNA
  • GTP-Binding Proteins
  • rab GTP-Binding Proteins
  • rab5 GTP-Binding Proteins

Associated data

  • GENBANK/X59152