Protease trafficking in two primitive eukaryotes is mediated by a prodomain protein motif

J Biol Chem. 1999 Jun 4;274(23):16249-56. doi: 10.1074/jbc.274.23.16249.


Trypanosome protozoa, an early lineage of eukaryotic cells, have proteases homologous to mammalian lysosomal cathepsins, but the precursor proteins lack mannose 6-phosphate. Utilizing green fluorescent protein as a reporter, we demonstrate that the carbohydrate-free prodomain of a trypanosome cathepsin L is necessary and sufficient for directing green fluorescent protein to the lysosome/endosome compartment. A proper prodomain/catalytic domain processing site sequence is also required to free the mature protease for delivery to the lysosome/endosome compartment. A nine-amino acid prodomain loop motif, implicated in prodomain-receptor interactions in mammalian cells, is conserved in the protozoa. Site-directed mutagenesis now confirms the importance of this loop to protease trafficking and suggests that a protein motif targeting signal for lysosomal proteases arose early in eukaryotic cell evolution.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Biological Transport
  • Cell Compartmentation
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism*
  • Enzyme Precursors / genetics
  • Enzyme Precursors / metabolism*
  • Green Fluorescent Proteins
  • Leishmania mexicana / enzymology*
  • Luminescent Proteins
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • Sequence Alignment
  • Structure-Activity Relationship
  • Trypanosoma cruzi / enzymology*


  • Enzyme Precursors
  • Luminescent Proteins
  • Protozoan Proteins
  • Green Fluorescent Proteins
  • Cysteine Endopeptidases
  • cruzain, Trypanosoma cruzi