Identification of the U-937 membrane-associated proteinase interacting with the V3 loop of HIV-1 gp120 as cathepsin G.
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.
Avril
L E
LE
Laboratoire d'Enzymologie, Centre National de la Recherche Scientifique URA 1334, University François Rabelais, Faculty of Medicine, Tours, France.
Di Martino-Ferrer
M
M
Pignede
G
G
Séman
M
M
Gauthier
F
F
D000595:Amino Acid Sequence; D001483:Base Sequence; D056649:Cathepsin G; D002403:Cathepsins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology*; D003429:Cross Reactions; D018076:DNA, Complementary / Q000235:genetics; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007962:Leukocytes / Q000201:enzymology; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010446:Peptide Fragments / Q000378:metabolism*; D017421:Sequence Analysis; D012697:Serine Endopeptidases; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D015699:HIV Envelope Protein gp120; D015345:Oligonucleotide Probes; D010446:Peptide Fragments; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G