Fibromodulin and lumican bind to the same region on collagen type I fibrils

Fibromodulin and lumican are closely related members of the extracellular m atric leucine-rich repeat glycoprotein/ proteoglycan family. Similar to dec orin, soother member of this protein family, they bind to fibrillar collage ns and function in the assembly of the collagen network in connective tissu es. We have studied the binding of recombinant fibromodulin, lumican and de corin, expressed in mammalian cells, to collagen type I, Using a collagen f ibril formation/sedimentation assay ne shea that fibromodulin inhibits the binding of lumican. and vice versa, Fibromodulin and lumican do not affect the binding of decorin to collagen, nor does decorin inhibit the binding of fibromodulin or lumican, Binding competition experiments and Scatchard plo t analysis indicate that fibromodulin binds to collagen type I with higher affinity than lumican. (C) 2000 Federation of European Biochemical Societie s.