title: Identification of a 10 S trypsin-like protease that cross-reacts with anti-proteasome antibody in sea urchin egg jelly.
abstract: We have identified 27- and 26-kDa polypeptides in sea urchin egg jelly, both of which cross-reacted with the antibody against 20 S proteasome (multicatalytic proteinase) isolated from sea urchin sperm. Separation of egg jelly fraction by gel filtration or sucrose density gradient centrifugation revealed that these polypeptides comigrated as a complex with a molecular size much smaller than that of proteasome: the apparent molecular mass and the sedimentation coefficient were 200 kDa and 10 S, respectively. This protease significantly hydrolyzed the fluorogenic synthetic substrates for trypsin-like protease but little hydrolyzed those for chymotrypsin-like protease. Trypsin-like activity of sperm proteasome was activated up to more than threefold by a low concentration of sodium dodecyl sulfate (SDS), whereas the egg jelly 10 S protease was inhibited by SDS. Two-dimensional immunoblot and peptide mapping revealed that the 26-kDa polypeptide is a degradative product of 27-kDa polypeptide and that the 10 S protease is composed of a proteasome-related single 27-kDa polypeptide and its modified forms. These results indicate the presence of a 10 S novel assembly of a proteasome subunit only with trypsin-like activity.
authors.affiliation: Misaki Marine Biological Station, School of Science, University of Tokyo, Kanagawa, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Inaba
authors.forename: M
authors.initials: M
authors.lastname: Morisawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D003429:Cross Reactions; D003546:Cysteine Endopeptidases / Q000276:immunology*; D010450:Endopeptidases / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification*; D005260:Female; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000276:immunology*; D009842:Oligopeptides / Q000737:chemistry; D010063:Ovum / Q000201:enzymology; D010449:Peptide Mapping; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D012617:Sea Urchins / Q000201:enzymology*; D013094:Spermatozoa / Q000201:enzymology; D013379:Substrate Specificity; D014357:Trypsin / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification*
chemical_list: D000906:Antibodies; D009097:Multienzyme Complexes; D009842:Oligopeptides; D011480:Protease Inhibitors; D010450:Endopeptidases; D014357:Trypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex