Identification of targeting proteinase for rat alpha 1-macroglobulin in vivo. Mast-cell tryptase is a major component of the alpha 1-macroglobulin-proteinase complex endocytosed into rat liver lysosomes.
The alpha 1-macroglobulin-proteinase complex endocytosed into rat liver lysosomes was purified by a series of column chromatographic steps on concanavalin A-Sepharose, Sephacryl S-300, DEAE-cellulose and TSK gel DEAE-5PW columns. The complex contained no detectable alpha 2-macroglobulin. Studies on the substrate specificity indicated that the complex had tryptase-like activities towards various synthetic substrates, but no elastase, chymotrypsin, cathepsin-B and cathepsin-L activities. The proteinase activity was completely inhibited by di-isopropyl fluorophosphate, leupeptin and antipain, indicating that the proteinase bound to alpha 1-macroglobulin is a serine proteinase. Two protein bands (62 and 59 kDa) of the complex were labelled with [3H]diisopropyl fluorophosphate and both bands cross-reacted with anti-(mast-cell tryptase)antibody. These results suggest that mast-cell tryptase is a major targeting proteinase for alpha 1-macroglobulin in vivo. The main alpha-macroglobulin-proteinase complex in the adjuvant-treated rats was also the alpha 1-macroglobulin-tryptase complex, even though the plasma level of alpha 2-macroglobulin was elevated.
Tsuji
A
A
Department of Biological Science and Technology, Faculty of Engineering, University of Tokushima, Japan.
Akamatsu
T
T
Nagamune
H
H
Matsuda
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D053818:Chymases; D004705:Endocytosis; D006863:Hydrogen-Ion Concentration; D007976:Leupeptins / Q000494:pharmacology; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology*; D008297:Male; D008407:Mast Cells / Q000201:enzymology*; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012697:Serine Endopeptidases / Q000378:metabolism*; D013379:Substrate Specificity; D053802:Tryptases; D000511:alpha-Macroglobulins / Q000378:metabolism*
D007976:Leupeptins; D011480:Protease Inhibitors; D000511:alpha-Macroglobulins; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; C509223:Tpsab1 protein, rat; C509221:Tpsb2 protein, rat; D053802:Tryptases; C032854:leupeptin