The BioGRID | PUBLICATION VIEW

	Arch. Biochem. Biophys. Sep (1989); 273(2):367-74
Interaction of lysosomal cysteine proteinases with alpha 2-macroglobulin: conclusive evidence for the endopeptidase activities of cathepsins B and H.
Mason RW
Department of Biochemistry, Strangeways Research Laboratory, Worts Causeway, Cambridge, United Kingdom.
Abstract: The lysosomal cysteine proteinases, cathepsins B, H, and L, were all shown to bind to alpha 2-macroglobulin. The bound enzymes remained active against low-molecular-weight synthetic substrates and bound the active-site-directed inhibitor, benzyloxycarbonyl-125I-Tyr-Ala-diazomethane. Binding of the radiolabeled inhibitor to high-molecular-weight protein on sodium dodecyl sulfate polyacrylamide gels indicated that a proportion of the enzymes was covalently bound to alpha 2-macroglobulin. Cleavage fragments of alpha 2-macroglobulin of Mr 92,000 and 86,000 were seen for cathepsins B, H, and L, indicating cleavage in the bait region. Binding and cleavage were observed for both single-chain and two-chain forms of cathepsin B from human, ox, and pig livers, showing that all active forms of cathepsins B, H, and L are endopeptidases.
[PUBMED: 2476070]