Cathepsin G binds to human lymphocytes.
Cathepsin G is a serine protease located in the azurophil granules of neutrophils. We have shown previously that cathepsin G stimulates human lymphocytes. In this study, we demonstrate that cathepsin G exhibits specific, saturable and reversible binding to lymphocytes: B cells, CD4+ T cells, CD8+ T cells, and natural killer (NK) cells. Phenylmethylsulfonyl fluoride (PMSF) -inhibited cathepsin G also bound to lymphocytes, although both the number of binding sites and the affinity were less than those of native cathepsin G. The binding of cathepsin G to lymphocytes showed cooperativity, but that of PMSF-inhibited cathepsin G did not. PMSF-inhibited cathepsin G was able to partially displace bound cathepsin G. These results suggest that molecules on the lymphocyte surface that bind cathepsin G recognize not only the active site of cathepsin G but also other sites of this molecule, but the active site has an important function in this binding because stimulation of lymphocytes requires the binding of proteolytically active cathepsin G.
Yamazaki
T
T
Department of Nutrition and Biochemistry, The Institute of Public Health, Tokyo, Japan.
Aoki
Y
Y
D001402:B-Lymphocytes / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D056649:Cathepsin G; D002403:Cathepsins / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005459:Fluorides / Q000494:pharmacology; D006801:Humans; D007457:Iodine Radioisotopes / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012697:Serine Endopeptidases; D013450:Sulfones / Q000494:pharmacology; D013696:Temperature
D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D013450:Sulfones; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D005459:Fluorides