Processing and transport of the precursor of cathepsin C during its transfer into lysosomes

Arch Biochem Biophys. 1993 Oct;306(1):103-10. doi: 10.1006/abbi.1993.1486.


The biosynthesis and processing of a lysosomal cysteine proteinase, cathepsin C (dipeptidylaminopeptidase I), was investigated by pulse-chase experiments in cultured rat macrophages. Cathepsin C is first synthesized as procathepsin C with a molecular mass of 55 kDa. Procathepsin C is then cleaved and modified within 1 h into mature cathepsin C with two chains of 25 and 7.8 kDa. A combination of pulse-chase experiments and the subcellular fractionation analysis showed that procathepsin C and cathepsin C are located in low-buoyant-density organelles and lysosomes, respectively. The reactivity of endoglycosidase H and N-glycanase and analysis of phosphorylation indicated that both precursor and mature cathepsin C are phosphorylated and N-glycosylated to give a high-mannose-type. The addition of 300-kDa mannose 6-phosphate receptor antiserum to the chase medium caused extensive release of procathepsin C into the medium, whereas the addition of control serum did not. The membrane association of procathepsin C was tested by successive extraction of cells pulse labeled for 75 min with hypotonic buffer, alkaline solution, and Triton X-100. Procathepsin C was totally extracted by hypotonic solution, whereas procathepsin D was a membrane-associated form requiring Triton X-100 for its extraction. Gel-filtration chromatography analysis of the pulse-labeled products revealed that the precursor product exists as an oligomeric form. It is suggested that the oligomerization of cathepsin C occurs before its entry into lysosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies
  • Autoradiography
  • Biological Transport
  • Cathepsin C
  • Cathepsin D / biosynthesis
  • Cathepsin D / isolation & purification
  • Cells, Cultured
  • Centrifugation, Density Gradient
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / biosynthesis*
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / isolation & purification
  • Enzyme Precursors / isolation & purification
  • Enzyme Precursors / metabolism*
  • Kinetics
  • Lysosomes / metabolism*
  • Macrophages, Peritoneal / enzymology*
  • Methionine / metabolism
  • Molecular Sequence Data
  • Molecular Weight
  • Protein Processing, Post-Translational*
  • Rats
  • Rats, Wistar
  • Sulfur Radioisotopes


  • Antibodies
  • Enzyme Precursors
  • Sulfur Radioisotopes
  • Methionine
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
  • Cathepsin C
  • Cathepsin D