Mitochondrial localization and oligomeric structure of HClpP, the human homologue of E. coli ClpP

J Mol Biol. 1999 Oct 1;292(4):819-25. doi: 10.1006/jmbi.1999.3121.


A bacterially expressed recombinant HClpP protein, the human homologue of Escherichia coli ClpP protease, was used to obtain specific polyclonal antibodies. Those antibodies identify a 26 kDa polypeptide in mitochondrial subcellular fractions of rat and human liver. Immunofluorescence and electron microscopic studies demonstrate that the mammalian homologue of ClpP is located in the mitochondrial matrix with a tendency to be found in association with the inner mitochondrial membrane. An HClpP recombinant protein with a truncated NH2terminus (missing the first 58 amino acid residues) shows a molecular mass of 26 kDa under denaturing conditions. This N-truncated HClpP recombinant protein shows a native molecular mass of 340 kDa that is identical with the native molecular mass of the partially purified protein from rat liver mitochondria. Electron microscopy shows that the N-truncated recombinant HClpP has a ring shape with seven identical morphological units in the periphery, exhibiting a 7-fold symmetry. The native molecular mass and the electron microscopic studies suggest that mitochondrial ClpP is composed of two heptameric rings with 7-fold symmetry, similar to E. coli ClpP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / analysis
  • Adenosine Triphosphatases / chemistry*
  • Adenosine Triphosphatases / metabolism*
  • Amino Acid Sequence
  • Animals
  • Antibodies
  • Cell Line
  • Chromatography, Gel
  • Endopeptidase Clp
  • Escherichia coli / chemistry
  • Escherichia coli / genetics
  • Fluorescent Antibody Technique
  • HeLa Cells
  • Humans
  • Intracellular Membranes / metabolism
  • Microscopy, Immunoelectron
  • Mitochondria, Liver / chemistry*
  • Mitochondria, Liver / metabolism
  • Mitochondria, Liver / ultrastructure
  • Molecular Sequence Data
  • Molecular Weight
  • Protein Binding
  • Protein Conformation
  • Rats
  • Recombinant Proteins / analysis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sequence Deletion
  • Serine Endopeptidases / analysis
  • Serine Endopeptidases / chemistry*
  • Serine Endopeptidases / metabolism*


  • Antibodies
  • Recombinant Proteins
  • Serine Endopeptidases
  • Endopeptidase Clp
  • Adenosine Triphosphatases