Xenopsin-related peptide(s) are formed from xenopsin precursor by leukocyte protease(s) and cathepsin D.
Lysates of isolated rat polymorphonuclear leukocytes and macrophages were found to generate xenopsin-related peptides when incubated with a liver extract used as a source of precursor. The lysosomal enzyme, cathepsin D, was also shown to display this property and to share with the lysate a similar pH dependence (optimum, approximately pH 3.5) and sensitivity to the acid protease inhibitor, pepstatin A (ID50: lysate, 10 nM; cathepsin D, 30 nM). When subjected to HPLC on mu-Bondapak C-18, the xenopsin-related peptides generated by the lysate eluted near to those formed by cathepsin D and when tested in a radioreceptor assay for neurotensin, they displayed similar cross-reactivities (peak 2, approximately 50%; peak 1, approximately 100%). These results indicate that cathepsin D from lysed granulocytes can process precursor protein(s) to form radioreceptor-active xenopsin-related peptides.
Carraway
R E
RE
Physiology Department, University of Massachusetts Medical School, Worcester 01655.
Mitra
S P
SP
Muraki
K
K
D000595:Amino Acid Sequence; D000818:Animals; D002402:Cathepsin D / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D006098:Granulocytes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007962:Leukocytes / Q000201:enzymology*; D008099:Liver / Q000737:chemistry; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000096:biosynthesis*; D010455:Peptides; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D029867:Xenopus Proteins
D009842:Oligopeptides; D010455:Peptides; D011498:Protein Precursors; D029867:Xenopus Proteins; C016832:xenopsin; D010450:Endopeptidases; D002402:Cathepsin D