Association of the macrophage activating factor (MAF) precursor activity with polymorphism in vitamin D-binding protein

Anticancer Res. 2004 Sep-Oct;24(5C):3361-6.


Background: Serum vitamin D-binding protein (Gc protein or DBP) is a highly expressed polymorphic protein, which is a precursor of the inflammation-primed macrophage activating factor, GcMAF, by a cascade of carbohydrate processing reactions. In order to elucidate the relationship between Gc polymorphism and GcMAF precursor activity, we estimated the phagocytic ability of three homotypes of Gc protein, Gc1F-1F, Gc1S-1S and Gc2-2, through processing of their carbohydrate moiety.

Materials and methods: We performed Gc typing of human serum samples by isoelectric focusing (IEF). Gc protein from human serum was purified by affinity chromatography with 25-hydroxyvitamin D3-sepharose. A phagocytosis assay of Gc proteins, modified using beta-glycosidase and sialidase, was carried out.

Results: The Gc1F-1F phenotype was revealed to possess Galbeta1-4GalNAc linkage by the analysis of GcMAF precursor activity using beta1-4 linkage-specific galactosidase from jack bean. The GcMAF precursor activity of the Gc1F-1F phenotype was highest among three Gc homotypes.

Conclusion: The Gc polymorphism and carbohydrate diversity of Gc protein are significant for its pleiotropic effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Carbohydrate Metabolism
  • Carbohydrates / chemistry
  • Chromatography, Affinity
  • Female
  • Humans
  • Isoelectric Focusing
  • Lymphokines / metabolism*
  • Mice
  • Middle Aged
  • Models, Molecular
  • Phagocytosis
  • Phenotype
  • Polymorphism, Genetic
  • Protein Conformation
  • Protein Precursors / metabolism*
  • Vitamin D-Binding Protein / blood*
  • Vitamin D-Binding Protein / classification
  • Vitamin D-Binding Protein / genetics*
  • Vitamin D-Binding Protein / isolation & purification
  • beta-Galactosidase / metabolism


  • Carbohydrates
  • Lymphokines
  • Protein Precursors
  • Vitamin D-Binding Protein
  • macrophage aggregation factor
  • beta-Galactosidase