title: Met-enkephalyl-Arg6-Phe7 immunoreactivity in a human neuroblastoma cell line: effect of dibutyryl 3':5'-cyclic AMP and reserpine.
abstract: The carboxy terminal part of the proenkephalin A sequence is the 31 amino acid peptide B, which has as its final seven amino acids the sequence of the opioid peptide Met-enkephalyl-Arg6-Phe7. Using a radioimmunoassay which recognises both these peptides we have investigated the relative amounts of peptide B and Met-enkephalyl-Arg6-Phe7 in a human neuroblastoma cell line. We show that these cells contain peptide B-like immunoreactivity but not its heptapeptide fragment. This may be due to lack of proteolytic activity cleaving Met-enkephalyl-Arg6-Phe7 from its precursor, peptide B. On treatment with dibutyryl cyclic AMP the level of immunoreactivity approximately doubles, due to increased amounts of peptide B-like immunoreactivity. Treatment with reserpine, which increases conversion of peptide B to the heptapeptide in bovine chromaffin cells in culture does not stimulate the accumulation of Met-enkephalyl-Arg6-Phe7 in the human neuroblastoma cells. The results are discussed with respect to peptide processing.
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000527:Alprostadil / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology*; D002460:Cell Line; D000242:Cyclic AMP / Q000032:analysis; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000032:analysis / Q000276:immunology; D004745:Enkephalins / Q000032:analysis; D006801:Humans; D009447:Neuroblastoma / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis; D011498:Protein Precursors / Q000032:analysis; D012110:Reserpine / Q000494:pharmacology*
chemical_list: D004745:Enkephalins; D010446:Peptide Fragments; D011498:Protein Precursors; C029992:proenkephalin; D004744:Enkephalin, Methionine; D003994:Bucladesine; C027511:enkephalin-Met, Arg(6)-Phe(7)-; D012110:Reserpine; D000242:Cyclic AMP; D000527:Alprostadil; D015056:1-Methyl-3-isobutylxanthine