An Arabidopsis mutant defective in the plastid general protein import apparatus

Science. 1998 Oct 2;282(5386):100-3. doi: 10.1126/science.282.5386.100.


Elaborate mechanisms have evolved for the translocation of nucleus-encoded proteins across the plastid envelope membrane. Although putative components of the import apparatus have been identified biochemically, their role in import remains to be proven in vivo. An Arabidopsis mutant lacking a new component of the import machinery [translocon at the outer envelope membrane of chloroplasts (Toc33), a 33-kilodalton protein] has been isolated. The functional similarity of Toc33 to another translocon component (Toc34) implies that multiple different translocon complexes are present in plastids. Processes that are mediated by Toc33 operate during the early stages of plastid and leaf development. The data demonstrate the in vivo role of a translocon component in plastid protein import.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / chemistry
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins*
  • Biological Transport
  • Chlorophyll / metabolism
  • Chloroplasts / metabolism*
  • Chloroplasts / ultrastructure
  • Gene Expression Regulation, Plant
  • Intracellular Membranes / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Plant Leaves / metabolism
  • Plant Proteins / metabolism*
  • Plants, Genetically Modified
  • Sequence Alignment


  • Arabidopsis Proteins
  • Membrane Proteins
  • Plant Proteins
  • TOC34 protein, Arabidopsis
  • Toc33 protein, Arabidopsis
  • Toc34 protein, plant
  • Chlorophyll