Structural variability of BM-40/SPARC/osteonectin glycosylation: implications for collagen affinity

Glycobiology. 2004 Jul;14(7):609-19. doi: 10.1093/glycob/cwh063. Epub 2004 Mar 24.

Abstract

We performed a detailed investigation of N-glycan structures on BM-40 purified from different sources including human bone, human platelets, mouse Engelbreth-Holm-Swarm (EHS) tumor, and human BM-40 recombinantly expressed in 293 and osteosarcoma cells. These preparations were digested with endoglycosidases and N-glycans were further characterized by sequential exoglycosidase digestion and high-performance liquid chromatography (HPLC) analyses. Bone BM-40 carries high-mannose structures as well as biantennary complex type N-glycans, whereas the protein from platelets and 293 cells has exclusively bi- and triantennary complex type structures. BM-40 derived from the EHS tumor carries biantennary complex type and additional hybrid structures. Using the osteosarcoma-derived MHH-ES1 cell line we successfully expressed a recombinant BM-40 that bears at least in part the bone-specific high-mannose N-glycosylation in addition to complex type and hybrid structures. Using chromatography on Concanavalin-A Sepharose, we further purified a fraction enriched in high-mannose structures. This array of differentially glycosylated BM-40 proteins was assayed by surface plasmon resonance measurements to investigate the binding to collagen I. BM-40 carrying high-mannose structures binds collagen I with higher affinity, suggesting that differentially glycosylated forms may have different functional roles in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood Platelets / chemistry
  • Bone and Bones / chemistry
  • Carbohydrate Sequence
  • Chromatography, High Pressure Liquid
  • Collagen / chemistry*
  • Collagen / metabolism
  • Glycoside Hydrolases / chemistry*
  • Glycosylation
  • Humans
  • Mannose / chemistry
  • Mice
  • Osteonectin / chemistry*
  • Osteonectin / isolation & purification*
  • Osteonectin / metabolism
  • Polysaccharides / chemistry*
  • Protein Binding
  • Sarcoma, Experimental / chemistry
  • Surface Plasmon Resonance

Substances

  • Osteonectin
  • Polysaccharides
  • Collagen
  • Glycoside Hydrolases
  • Mannose