Mechanism of protein import across the chloroplast envelope

Biochem Soc Trans. 2000;28(4):485-91.


The development and maintenance of chloroplasts relies on the contribution of protein subunits from both plastid and nuclear genomes. Most chloroplast proteins are encoded by nuclear genes and are post-translationally imported into the organelle across the double membrane of the chloroplast envelope. Protein import into the chloroplast consists of two essential elements: the specific recognition of the targeting signals (transit sequences) of cytoplasmic preproteins by receptors at the outer envelope membrane and the subsequent translocation of preproteins simultaneously across the double membrane of the envelope. These processes are mediated via the co-ordinate action of protein translocon complexes in the outer (Toc apparatus) and inner (Tic apparatus) envelope membranes.

Publication types

  • Review

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis Proteins*
  • Biological Transport
  • Cell Membrane / metabolism
  • Cell Nucleus / metabolism
  • Chloroplasts / metabolism*
  • Cytoplasm / metabolism
  • GTP Phosphohydrolases / chemistry
  • GTP Phosphohydrolases / genetics
  • Gene Deletion
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Models, Biological
  • Molecular Sequence Data
  • Plant Physiological Phenomena*
  • Plant Proteins*
  • Protein Precursors / chemistry
  • Protein Precursors / genetics
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid


  • Arabidopsis Proteins
  • Membrane Proteins
  • OEP75 protein precursor, plant
  • Plant Proteins
  • Protein Precursors
  • TOC159 protein, Arabidopsis
  • TOC34 protein, Arabidopsis
  • TOC75 protein, Arabidopsis
  • Toc34 protein, plant
  • GTP Phosphohydrolases