Identification of the U-937 membrane-associated proteinase interacting with the V3 loop of HIV-1 gp120 as cathepsin G

FEBS Lett. 1994 May 23;345(1):81-6. doi: 10.1016/0014-5793(94)00410-2.


We have purified a serine proteinase from the membrane of U-937 cells that was inhibited in a tight-binding manner by recombinant gp120 and by peptides mimicking the V3 loop of gp120 [(1993) FEBS Lett. 317, 167-172]. This proteinase has now been characterized, both structurally and functionally. It has a dual trypsin- and chymotrypsin-like specificity, and N-terminal sequence analysis of the first 32 residues indicates complete identity with leukocyte cathepsin G. Cathepsin G-like material was located at the surface of U-937 cells using a monoclonal antibody directed against leukocyte cathepsin G, and polyclonal anti-cathepsin G antibodies precipitated the purified proteinase. However, the U-937 enzyme differs slightly from commercial leukocyte cathepsin G in its apparent M(r) because of different glycosylation. No other protein structurally related to cathepsin G was found upon screening a U-937 cDNA library using several oligonucleotide probes constructed from the membrane proteinase N-terminal amino acid sequence. The possible interaction of a cathepsin G-like proteinase at the surface of U-937 cells with the V3 loop of HIV-1 gp120 is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cathepsin G
  • Cathepsins / immunology
  • Cathepsins / isolation & purification*
  • Cathepsins / metabolism*
  • Cell Membrane / enzymology*
  • Cross Reactions
  • DNA, Complementary / genetics
  • HIV Envelope Protein gp120 / metabolism*
  • Humans
  • Immunoblotting
  • Leukocytes / enzymology
  • Molecular Sequence Data
  • Oligonucleotide Probes
  • Peptide Fragments / metabolism*
  • Sequence Analysis
  • Serine Endopeptidases
  • Substrate Specificity
  • Tumor Cells, Cultured


  • DNA, Complementary
  • HIV Envelope Protein gp120
  • Oligonucleotide Probes
  • Peptide Fragments
  • Cathepsins
  • Serine Endopeptidases
  • CTSG protein, human
  • Cathepsin G