Molecular cloning and characterization of maize Toc34, a regulatory component of the protein import machinery of chloroplast

Biochim Biophys Acta. 2000 Apr 25;1491(1-3):309-14. doi: 10.1016/s0167-4781(00)00043-9.


Several components of the chloroplast protein import machinery have been identified mostly in the C3 dicot plant pea. We describe here two homologous cDNA sequences of Toc34, a regulatory component of the import machinery, from maize, a C4 monocot plant. The deduced amino acid sequences of two maize Toc34 proteins, named ZmToc34-1 and ZmToc34-2, show 95% identity to each other and about 60% to those of previously identified Toc34 proteins. The GTP-binding motif and the presumed carboxyl terminal membrane anchor are also conserved in the ZmToc34 proteins. The maize Toc34, like that of pea, is tightly associated with the outer envelope membrane of chloroplast and exposed to the cytosol.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Chloroplasts / metabolism*
  • Cloning, Molecular
  • DNA, Complementary / chemistry
  • DNA, Complementary / genetics
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics*
  • Molecular Sequence Data
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription, Genetic
  • Zea mays / genetics*


  • DNA, Complementary
  • Membrane Proteins
  • Plant Proteins
  • Toc34 protein, plant