title: A secreted peptidase involved in T cell beta-endorphin metabolism.
abstract: Beta-endorphin metabolism by CD4+ and CD8+ T cells, and the thymoma cell line, EL4, was investigated. In all three cell types, extracellular beta-endorphin was metabolized exclusively by a secreted, metal-dependent, thiol peptidase. The enzyme activity is expressed constitutively in EL4 cells and following activation of CD4+ and CD8+ T cells with anti-CD3 antibody. The enzyme is not one of the proteinases associated with cytolytic T cells and does not appear to be identical with any previously described beta-endorphin metabolizing enzyme. The enzyme cleaves beta-endorphin at approximately equal rates at either of two sites to yield beta-endorphin(1-17) (which is gamma-endorphin), beta-endorphin(1-18), beta-endorphin(18-31) and beta-endorphin(19-31). Evidence in the literature indicates that these N- and C-terminal peptides which contain, respectively, the opioid and non-opioid receptor binding domains of beta-endorphin, are biologically active. Thus, it is likely that this new T cell peptidase has important immunoregulatory activity.
authors.affiliation: Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, TX 75235-9038, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: Miller
authors.forename: D
authors.initials: D
authors.lastname: Thiele
authors.forename: L B
authors.initials: LB
authors.lastname: Hersh
authors.forename: G L
authors.initials: GL
authors.lastname: Cottam
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D002162:Camelus; D002478:Cells, Cultured; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013945:Thymoma; D014407:Tumor Cells, Cultured; D001615:beta-Endorphin / Q000378:metabolism*
chemical_list: D013438:Sulfhydryl Compounds; D001615:beta-Endorphin; D010450:Endopeptidases