Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.25.1 (proteasome)
28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pen a 1, the major shrimp allergen from the brown shrimp Penaeus aztecus was purified by preparative SDS-PAGE. Peptides were generated from Pen a 1 by CNBr cleavage and endoproteinase (Lys-C, Glu-C, trypsin, alkaline protease, Arg-C, chymotrypsin) digestion. The molecular weights of the resulting CNBr cleavage and enzymatic digestion products, separated by peptide SDS-PAGE, ranged from 1.5 to 20 kD. Following SDS-PAGE and semidry blotting, the analysis of monoclonal antibody (mAb) and subjects' IgE reactivities demonstrated that with the exception of alkaline protease, all cleavage procedures yielded IgE-binding peptides. However, since not all peptides of every digest bind IgE, it appears that IgE-binding epitopes are restricted to certain parts of the Pen a 1 molecule. mAbs bound to CNBr, Lys-C, trypsin, Glu-C and Arg-C peptides. Since mAbs reacted to several peptides from the same digest, Pen a 1 may have several similar epitopes. The comparison of IgE and mAb reactivities demonstrated similar but not identical binding patterns.
...
PMID:Antigenic analysis (IgE and monoclonal antibodies) of the major shrimp allergen Pen a 1 (Tropomyosin) from Penaeus aztecus. 754 76

We have identified and purified an endogenous inhibitor of multicatalytic proteinase (MCP) from human erythrocyte membranes. The inhibitor showed a molecular mass of 90 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The inhibitor protein was purified from the erythrocyte membranes using Heparinagarose and hydroxylapatite chromatography and the size exclusion on a Biogel A 1.5 m column in the presence of high salt. The 90-kDa protein inhibited all three peptidase activities of MCP; trypsin-like, chymotrypsin-like and peptidyl glutamyl peptide hydrolyzing (PGPH). However, it failed to cause any significant inhibition of caseinolytic activity of MCP, suggesting that the regulation of proteinase and peptidase activities is distinct. The inhibition of the chymotrypsin-like activity was noncompetitive. The results suggest that the 90-kDa inhibitor protein may be an important regulator of membrane-bound MCP.
...
PMID:Identification and purification of a 90-kDa membrane-bound endogenous inhibitor of multicatalytic proteinase from human erythrocytes. 757 69

Six basic proteins of 26 to 38 kDa with isoelectric points (pI) > or = 8.5 were abundant in proteins separated by two-dimensional SDS-PAGE from adult rat peritoneal mast cells (MC). One was identified previously as rat mast cell proteinase (RMCP) 1, a chymase of 26 to 28 kDa, pI > 9.0. Microsequence analyses showed that two polypeptides of about 29 and 30 kDa had NH2 terminal amino acid sequences homologous to mouse MC proteinase 5 (MCP-5), whereas the amino terminals of the 33, 35, and 36 kDa proteins were homologous to MC carboxypeptidase A (MC-CPA). Rabbit Abs produced against synthetic peptides of the identified NH2 terminal sequences were used in immunoblot studies. At least three proteins reacted with Abs to MC-CPA, whereas Abs to MCP-5 detected three adjacent polypeptides, rather than just the two identified by using microsequence analysis. Removal of oligosaccharide side chains using peptide:N-glycosidase F reduced the heterogeneity of each set of three polypeptides (MCP-5 and MC-CPA) to a band of each protein of a lower M(r). The serine proteinase inhibitor [3H]diisopropylfluorophosphate ([3H]DFP) bound to a proteinase of 30 to 35 kDa, which is probably MC tryptase (pI < or = 6.0). Immunoblot analysis of proteins from intestinal mucosal mast cells showed RMCP-2, but not RMCP-1, MCP-5, or MC-CPA. This is the first report of MCP-5 in the rat and of clearly distinguishable glycosylated forms of MC CPA. These proteinases appear to be restricted in their distribution to selected MC populations, but little is known about their functions.
...
PMID:Proteinases of rat mast cells. Peritoneal but not intestinal mucosal mast cells express mast cell proteinase 5 and carboxypeptidase A. 759 1

Polyacrylamide gel electrophoresis and high performance liquid chromatography of multicatalytic proteinase complexes (MPC) isolated from bovine pituitary, lung, and liver showed marked differences in the pattern of subunits. The concentrations of LMP7 in the lung and liver were 10 and 5 times, respectively, greater than those in the pituitary, whereas the chymotrypsin-like activity and the amount of a subunit (BO2), necessary for its expression, were markedly decreased in the lung and moderately decreased in the liver. Lower trypsin-like, small neutral amino acid preferring, and peptidyl-glutamyl-peptide hydrolyzing activities were also found in the lung and liver. The activity of the branched chain amino acid preferring component (BrAAP), predominantly latent in the pituitary, was highly activated in the lung and liver, as evidenced by a greatly decreased Km and a 20-fold increase of the specificity constant Vmax/Km, indicating facilitated substrate access to its active site and increased affinity toward substrates with branched chain amino acids in the P1 position. It is suggested that overexpression of LMP7 in the lung is related to increased exposure of the airways to foreign antigens. The possible association between amounts of LMP7 and the activation of the BrAAP component needs further examination.
...
PMID:Differences in catalytic activities and subunit pattern of multicatalytic proteinase complexes (proteasomes) isolated from bovine pituitary, lung, and liver. Changes in LMP7 and the component necessary for expression of the chymotrypsin-like activity. 767 55

The multicatalytic proteinase complex (MPC), also called the proteasome, is a ubiquitous particle (19S) that is required for life. It is found in the cytoplasm and nucleus of all eukaryotic cells where it degrades selected cytosolic and nuclear proteins. It forms the proteolytic core of the 26S complex that represents the final step in the ubiquitin-dependent pathway of proteolysis. The MPC expresses at least five distinct proteolytic activities. Three activities preferring cleavages on the carboxyl side of neutral amino acids were described: an activity cleaving after branched chain residues, termed branched chain amino acid preferring, that is a major factor in the degradation of proteins, an activity preferring cleavages after bulky hydrophobic residues designated chymotrypsin-like, and an activity cleaving between small neutral amino acids. Activities cleaving after basic (trypsin-like) and acidic residues (peptidylglutamyl peptide-hydrolyzing) have also been described. The expression of multiple proteolytic activities with diverse specificities may provide a functional advantage that allows efficient hydrolysis of target proteins.
...
PMID:Catalytic components of the bovine pituitary multicatalytic proteinase complex (proteasome). 769 27

We have isolated and characterized a cDNA encoding the mouse proteasome subunit MC3 and identified four proteasome subtypes which differ in their peptide-hydrolyzing and polypeptide-cleavage properties. Immunoblotting data show that the 25-kD MC3 subunit is a constitutive proteasome subunit which exists in several isoforms. In addition, by immunoprecipitation of proteasomes with AbMC3, a subset of enzyme complexes could be recognized which differ in their relative subunit composition from the bulk of proteasomes. Using DEAE-column chromatography we identified three different proteasome subtypes in sol-80 mouse liver extracts and, by Trition X-100 extraction, a distinct membrane-bound subtype. The four proteasome subtypes are shown to differ in their trypsin- and chymotrypsin-like hydrolyzing activities as well as in their ability to cleave a 25mer polypeptide substrate derived from the MCMV IE pp89. Our data indicate that the enzymatic properties observed for the total proteasome population may be the summary of cleavage properties of different types of proteasome complexes.
...
PMID:Characterization of mouse proteasome subunit MC3 and identification of proteasome subtypes with different cleavage characteristics. Proteasome subunits, proteasome subpopulations. 769 31

The proteasome plays a central role in ubiquitin-dependent and -independent proteolysis in eukaryotic cells. The hawkmoth proteasome was purified from larval body wall and characterized with respect to substrate specificity, sensitivity to protease inhibitors, and cross-reactivity with monoclonal antibodies (mAbs) raised against human placenta proteasome. Leupeptin selectively inhibited the trypsin-like activity (T-L) and N-ethylmaleimide inhibited both T-L and chymotrypsin-like activities, whereas 0.02% sodium dodecyl sulfate stimulated the peptidylglutamyl peptide hydrolase, branched-chain amino acid preferring, and caseinolytic activities 20-, 18-, and 3.8-fold, respectively. All four peptidase activities were inhibited by 3,4-dichloroisocoumarin. One-dimensional immunoblot analysis showed that the level and subunit composition of the proteasome varied between tissues. The relative levels of proteasome were high in intersegmental muscle and ovary, lower in Malpighian tubule, male accessory gland, and ventral nerve cord, and lowest in flight muscle and fat body. The tissues differed in the relative amount of a 41-kDa doublet; a 22-kDa subunit was present only in the male accessory gland. Two-dimensional polyacrylamide gel electrophoresis showed that the hawkmoth proteasome contained at least 26 subunits, compared with 28 subunits in lobster. Immunological analysis using four subunit-specific mAbs identified the putative homologs of the human zeta, C2, C3, and C8 alpha-type subunits in the hawkmoth and lobster enzymes. Two of the four mAbs reacted with three or more of the hawkmoth subunits and three of the mAbs reacted with two or more of the lobster subunits. In addition, two other mAbs that recognize epitopes shared by a number of alpha-type subunits indicated that at least 15 (lobster) or 16 (hawkmoth) subunits were alpha-type. These results suggest that much of the subunit complexity of the arthropod proteasomes is a consequence of extensive post-translational modifications.
...
PMID:The multicatalytic proteinase (proteasome) of the hawkmoth, Manduca sexta: catalytic properties and immunological comparison with the lobster enzyme complex. 772 56

Lactacystin is a Streptomyces metabolite that inhibits cell cycle progression and induces neurite outgrowth in a murine neuroblastoma cell line. Tritium-labeled lactacystin was used to identify the 20S proteasome as its specific cellular target. Three distinct peptidase activities of this enzyme complex (trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolyzing activities) were inhibited by lactacystin, the first two irreversibly and all at different rates. None of five other proteases were inhibited, and the ability of lactacystin analogs to inhibit cell cycle progression and induce neurite outgrowth correlated with their ability to inhibit the proteasome. Lactacystin appears to modify covalently the highly conserved amino-terminal threonine of the mammalian proteasome subunit X (also called MB1), a close homolog of the LMP7 proteasome subunit encoded by the major histocompatibility complex. This threonine residue may therefore have a catalytic role, and subunit X/MB1 may be a core component of an amino-terminal-threonine protease activity of the proteasome.
...
PMID:Inhibition of proteasome activities and subunit-specific amino-terminal threonine modification by lactacystin. 773 82

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.
...
PMID:Identification of a 10 S trypsin-like protease that cross-reacts with anti-proteasome antibody in sea urchin egg jelly. 777 82

Two high molecular mass proteinases, multicatalytic proteinase (MCP) and a new high molecular mass proteinase (HMP) with only chymotrypsin-like activity (Khan et al. (1994) J. Biol. Chem. 269, 10016-10021) from human erythrocyte membranes, have been compared. For this purpose, MCP was purified from human erythrocyte membranes in the active form towards synthetic peptide substrates; it also hydrolysed the protein substrates [14]methyl casein and [14C]oxidised insulin beta chain at 37 degrees C. MCP from plasma membranes exhibited hollow cylindrical structures also typical of cytosolic forms. Radiolabelled diisopropyl fluorophosphate, [3H]DFP, a serine proteinase inhibitor, labelled a band of Mr 23 000 in membrane MCP. By contrast, no labelling was obtained with HMP. Chymotrypsin-like activity of HMP was also found to be insensitive to DFP. On the other hand, DFP inhibited chymotrypsin-like and peptidylglutamyl peptide hydrolysing activities of membrane MCP, with no effect on its trypsin-like activity. The inhibition of MCP by DFP was concentration-dependent. These studies showed that MCP and HMP represent two distinct kinds of proteinases with chymotrypsin-like activities and can be distinguished by the serine proteinase inhibitor DFP.
...
PMID:Membrane-bound high molecular mass proteinases from human erythrocytes. 781 93


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---