title: A novel serine proteinase (HuTSP) isolated from a cloned human CD8+ cytolytic T cell line is expressed and secreted by activated CD4+ and CD8+ lymphocytes.
abstract: A novel proteinase, termed human T cell-associated serine proteinase (HuTSP), has been highly purified from a human CD8+ T lymphocyte clone. By using a panel of chromogenic model peptide substrates the enzyme was found to specifically recognize L-arginine and to cleave Tos-Gly-Pro-Arg-nitroanilide with high efficiency at a pH optimum of 10.5-11. Exposure to class-specific proteinase inhibitors revealed that HuTSP is a serine endopeptidase. The enzyme has a mol. mass of approximately 50 kDa (non-reduced) and of approximately 25-30 kDa (reduced) when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggesting HuTSP to be a disulfide-linked dimer. The enzyme is shown to be inducible by lectin in both CD4+ and CD8+ lymphocytes. Moreover, HuTSP was detected in a number of independent CD4+ and CD8+ T cell clones and was found to be released from effector cells upon ligand binding to the CD3-T cell receptor complex.
mesh_terms: D002999:Clone Cells / Q000201:enzymology; D004790:Enzyme Induction; D053804:Granzymes; D006801:Humans; D008213:Lymphocyte Activation; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D013602:T-Lymphocytes, Cytotoxic / Q000201:enzymology* / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000201:enzymology* / Q000378:metabolism
chemical_list: D053804:Granzymes; D012697:Serine Endopeptidases; C509212:GZMA protein, human