Isolation and characterization of glycine-rich gelatin-binding protein, a plasma glycoprotein which interacts with gelatin, arginine, heparin, and hyaluronic acid.

A gelatin-binding protein was isolated from porcine blood plasma by affinity chromatography in sequence on columns of Sepharose 4B coupled with gelatin, arginine, and heparin and by gel filtration through Sephadex G-200. The protein was bound strongly to the arginine column and thus could be separated from fibronectin. It reacted with concanavalin A and contained about 5% carbohydrate consisting of neutral sugars (2.6% by weight), hexosamine (1.5%), and sialic acid (0.55%). The glycoprotein also showed an interaction with hyaluronic acid, but not with unsubstituted Sepharose 4B. It consisted of 8 to 10 disulfide-linked subunits of about 47,000 daltons and contained more glycine and less proline than fibronectin. Thus we tentatively named this glycoprotein glycine-rich gelatin-binding protein (GGP). GGP did not react with antifibronectin antiserum. These results indicate that GGP is a glycoprotein which is distinct from fibronectin. However, there remains a possibility that GGP may be derived in vivo from fibronectin.