Cleavage of Pro-X and Glu-X Bonds Catalyzed by the Branched Chain Amino Acid Preferring Activity of the Bovine Pituitary Multicatalytic Proteinase Complex (20S Proteasome)

1996 ◽  
Vol 334 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Christopher Cardozo ◽  
Wei-Er Chen ◽  
Sherwin Wilk
Keyword(s):  
Amino Acid ◽  
20S Proteasome ◽  
Multicatalytic Proteinase ◽  
Branched Chain Amino Acid ◽  
Branched Chain ◽  
Multicatalytic Proteinase Complex

scholarly journals Branched-chain-amino-acid-preferring peptidase activity of the lobster multicatalytic proteinase (proteasome) and the degradation of myofibrillar proteins

1995 ◽  
Vol 306 (1) ◽  
pp. 285-291 ◽  
Author(s):  
D L Mykles ◽  
M F Haire
Keyword(s):  
Amino Acid ◽  
Myofibrillar Proteins ◽  
Significant Finding ◽  
Peptidase Activity ◽  
Multicatalytic Proteinase ◽  
Branched Chain Amino Acid ◽  
Endogenous Protein ◽  
Proteolytic Activities ◽  
Branched Chain

The multicatalytic proteinase (MCP or proteasome) is a large proteolytic complex that contains at least five catalytic components: the trypsin-like, chymotrypsin-like, peptidylglutamyl-peptide hydrolase (PGPH), branched-chain-amino-acid-preferring (BrAAP) and small-neutral-amino-acid-preferring activities. We have shown that brief heating of the lobster muscle proteasome activates a proteolytic activity that degrades casein and myofibrillar proteins and is distinct from the trypsin-like, chymotrypsin-like and PGPH components. Here we identify the BrAAP activity as a catalytic component involved in the initial degradation of myofibrillar proteins in vitro. This conclusion is based on the following. (1) The BrAAP component was activated by heat-treatment, whereas the other four peptidase activities were not. (2) The BrAAP and proteolytic activities showed similar sensitivities to cations and protease inhibitors: both were inhibited by 3,4-dichloroisocoumarin, chymostatin, N-ethylmaleimide and Mg2+, but were not affected by leupeptin, phenylmethanesulphonyl fluoride or Li+. (3) The BrAAP activity was inhibited most strongly by casein substrates and troponin; conversely, the troponin-degrading activity was inhibited by the BrAAP substrate. Another significant finding was that incubation of the heat-activated MCP in the presence of chymostatin resulted in the limited cleavage of troponin-T2 (45 kDa) to two fragments of 41 and 42 kDa; this cleavage was completely suppressed by leupeptin. These results suggest that under certain conditions the trypsin-like component can cleave endogenous protein.

Proteasome from cytokine-treated human cells shows stimulated BrAAP activity and depressed PGPH activity

2000 ◽  
Vol 78 (2) ◽  
pp. 115-118 ◽  
Author(s):  
Judith E Nelson ◽  
Claudia Altschuller-Felberg ◽  
Anna Loukissa ◽  
Christopher Cardozo
Keyword(s):  
Interferon Gamma ◽  
Umbilical Vein ◽  
Necrosis Factor Alpha ◽  
Multicatalytic Proteinase ◽  
Branched Chain Amino Acid ◽  
Factor Alpha ◽  
Branched Chain ◽  
Umbilical Vein Endothelial Cells ◽  
Multicatalytic Proteinase Complex ◽  
Necrosis Factor

The branched chain amino acid-preferring (BrAAP) activity of multicatalytic proteinase complex isolated from human umbilical vein endothelial cells and treated with interferon-gamma was increased more than 2-fold, which was associated with a marked increase in LMP7 expression and decreased peptidylglutamyl peptide-hydrolyzing activity. Increases in BrAAP activity in supernatants from cells treated with interferon-gamma, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, or lipopolysaccharide paralleled the increases in LMP7 expression. These findings are consistent with the conclusion that the increased BrAAP activity of LMP-containing multicatalytic proteinase complex results from incorporation of LMP7 or other LMP subunits.

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