Redox regulation of a src family protein tyrosine kinase p56lck in T cells.
Protein tyrosine phosphorylation was examined after T cells were exposed to oxidative stress in vitro to investigate the possible involvement of redox regulation in T-cell signaling. Oxidative reagents such as hydrogen peroxide (H2O2) and diamide, which oxidize the free sulfhydryl groups in the cells, markedly induced tyrosine phosphorylation of multiple cellular proteins, especially a 55-kDa protein, of cultured peripheral blood T lymphocytes (PBL blasts). The 55-kDa molecule phosphorylated by diamide turned out to be a src family protein tyrosine kinase, p56lck. The immune complex kinase assay showed that the kinase activity of p56lck of diamide-treated PBL blasts was enhanced. The tryptic peptide mapping of p56lck demonstrated that diamide induced the phosphorylation both at Tyr-394 (autophosphorylation site) and at Tyr-505 (negative regulatory site). Taken together, the tyrosine phosphorylation and presumably kinase activity of p56lck were swiftly enhanced by oxidative stress, indicating that T cells have a redox-sensitive signaling mechanism, which is partly mediated by the lymphocyte-specific protein tyrosine kinase p56lck.
Nakamura
K
K
Department of Biological Responses, Kyoto University, Japan.
Hori
T
T
Sato
N
N
Sugie
K
K
Kawakami
T
T
Yodoi
J
J
D002478:Cells, Cultured; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010084:Oxidation-Reduction; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology*; D014443:Tyrosine / Q000378:metabolism
D013438:Sulfhydryl Compounds; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)