Characterization and purification of T lymphocyte aminopeptidase B: a putative marker of T cell activation.
We have previously described that human T lymphocytes express membrane-associated peptidase activities (Mari et al., EMBO J., 1992, 11:3875). We show in this report that intact Jurkat T cells readily cleaved H-Arg-paranitroanilide, an aminopeptidase B (AP-B) substrate. The identification of the hydrolyzing activity as AP-B was confirmed by its sensitivity to both arphamenine B and bestatin in the nanomolar range. Significant AP-B activity was released in the supernatant upon incubation of intact T lymphocytes at 37 degrees C. However, AP-B activity was found mainly in the cytosolic fraction of Jurkat T cells. Cytosolic T cell AP-B was purified to homogeneity and exhibited a molecular mass of 72 kDa. Purified AP-B cleaved N-terminal basic amino acid-containing peptides such as thymopentin (H-Arg-Lys-Asp-Val-Tyr-OH), indicating that it might play a role in the regulation of the concentration of important soluble mediators of T cell activation. A rabbit polyclonal antibody was shown to recognize AP-B as assessed by both immunoprecipitation and Western blot experiments. Finally, we found that AP-B was up-regulated during activation of normal and leukemic T lymphocytes.
Belhacene
N
N
INSERM U 364, Faculté de Médecine, Nice, France.
Mari
B
B
Rossi
B
B
Auberger
P
P
D000626:Aminopeptidases / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D015415:Biomarkers; D015153:Blotting, Western; D006801:Humans; D008213:Lymphocyte Activation; D011233:Precipitin Tests; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology; D015854:Up-Regulation
D015415:Biomarkers; D000626:Aminopeptidases; C019721:aminopeptidase B