Biglycan is a 200-350 kD proteoglycan consisting of a 45 kD core protein and two chrondroitin/dermatan sulfate glycosaminoglycan chains. Biglycan binds to TGF-?. It also binds to collagen type I in low ionic strength (less than 3 mM phosphate) buffer. At higher ionic strengths, Biglycan does not bind to collagen type I. It enhances the inhibition effect of TGF-? on osteoclast proliferation at a concentration of 4-20 mg/ml. It also prevents the attachment of CHO cells to fibronectin, with a 50% inhibition at 17-21 mg/ml.