BINDING OF THE CYSTEINE PROTEINASES PAPAIN AND CATHEPSIN B-LIKE TO COATED LAMININ - USE OF SYNTHETIC PEPTIDES FROM LAMININ AND FROM THE LAMININ-BINDING REGION OF THE BETA(1) INTEGRIN SUBUNIT TO CHARACTERIZE THE BINDING-SITE

Cysteine proteinases of the papain superfamily, i.e., papain and cathe psin B-like proteinase, were found to be able to bind to laminin-coate d wells, When papain and cathepsin B-like proteinase were used, satura ble binding curves were found, The characterization of the binding sit e was carried out using synthetic peptides which corresponded to the m ost relevant functional sites of laminin and an octapeptide from the l aminin binding region of the beta(1) integrin subunit. In binding expe riments, the decapeptide RNIAEIIKDI and the pentapeptide YIGSR were ab le to displace papain and cathepsin B-like proteinase from coated lami nin. Nevertheless, the integrin beta(1) peptide DLYYLIMDL was the most powerful in the same experimental system. From these results, the C-t erminal region of this cross-shaped protein, i.e., the end of the long arm, and the region including the YIGSR sequence of the short arm of the beta chain would be the cysteine proteinase binding site. This bin ding site is probably the result of the network organization of lamini n which brings two regions, separated on a single laminin molecule, in to proximity. In previous work, digestion of basement membranes has be en found to be associated with the binding of cysteine proteinases to these supramolecular structures [N. Guinec, V. Dalet-Fumeron, and M. P agano (1992) FEBS Lett. 308, 305-308]. The present report demonstrates that laminin is the cysteine proteinase binding protein of basement m embranes. This property of laminin could be associated with tumor inva sion and other tissue remodeling processes linked to proteolysis of ba sement membranes and extracellular matrices. (C) 1998 Academic Press.