INTERACTION OF THE SMALL PROTEOGLYCAN DECORIN WITH FIBRONECTIN - INVOLVEMENT OF THE SEQUENCE NKISK OF THE CORE PROTEIN

Decorin, an interstitial small proteoglycan, was shown to interact with fibronectin via its core protein. In a solid-phase assay, both high-affinity (K(D) values between 10 and 20 nm) and low-affinity (K(D) values between 110 and 130 nM) binding sites were found. The central position of decorin core protein is made up of several repeats containing NKISK in positions 85-89 and similar sequences in other repeats. The pentapeptide inhibited, albeit not completely, the high-affinity interaction between decorin and fibronectin in a specific charge-independent manner. Half-maximal inhibition occurred at a peptide concentration of 10-mu-M. Core-protein-derived peptides that had been produced by endoproteinase Lys-C digestion were not inhibitory, but endoproteinase Arg-C-generated peptides served as inhibitors of binding. These results suggest that NKISK as a component of repetitive sequences of decorin is involved in the interaction between the proteoglycan and fibronectin.