Cathepsin L is capable of truncating cystatin C of 11 N-terminal amino acids

FEBS Lett. 1999 Jul 16;455(1-2):92-6. doi: 10.1016/s0014-5793(99)00824-8.


Cystatin C with the 11 N-terminal amino acids truncated shows a much lower affinity for cysteine proteinases than the intact inhibitor. Such truncation of cystatin C is recorded after action of glycyl endopeptidase and cathepsin L. Incubation of cystatin C with papain, cathepsin B or cathepsin H led to no changes in the cystatin C molecule. Isoelectric focusing of the cathepsin L and cystatin C mixture showed the formation of two new bands. One of them appeared whether E-64 or PMSF was added or not, evidently representing a cystatin C/cathepsin L complex. The other band is the truncated cystatin C molecule. N-terminal sequencing after separation by HPLC showed that cystatin C is cleaved by cathepsin L at the Gly11-Gly12 bond. The action of cathepsin L on cystatin C may be explained by the cleavage of the scissile bond in an inappropriate complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cathepsin L
  • Cathepsins / metabolism*
  • Chromatography, High Pressure Liquid
  • Cystatin C
  • Cystatins / chemistry
  • Cystatins / metabolism*
  • Cysteine Endopeptidases
  • Cysteine Proteinase Inhibitors / pharmacology
  • Electrophoresis, Polyacrylamide Gel
  • Endopeptidases*
  • Humans
  • Isoelectric Focusing
  • Protein Conformation
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism


  • CST3 protein, human
  • Cystatin C
  • Cystatins
  • Cysteine Proteinase Inhibitors
  • Recombinant Proteins
  • Cathepsins
  • Endopeptidases
  • Cysteine Endopeptidases
  • CTSL protein, human
  • Cathepsin L