Recombinant soluble human Fcgamma receptor I with picomolar affinity for immunoglobulin G

Biochem Biophys Res Commun. 2005 Dec 30;338(4):1811-7. doi: 10.1016/j.bbrc.2005.10.162. Epub 2005 Nov 2.


The ectodomain of human FcgammaRI (rsCD64) was expressed in HEK 293T cells and purified by immobilized-metal affinity chromatography. Binding activity to human IgG was verified by ELISA and the isotype-specificity determined by a surface plasmon resonance inhibition assay was found to be the same as for native CD64. The active concentration of the rsCD64 preparation was derived using a solution competition assay and was used for the subsequent kinetic analysis. Binding curves were well described by a simple monovalent interaction model confirming the known stoichiometry of the interaction. Mass-transport limitation was prevented by using sufficiently low surface capacities. For binding to the recombinant mouse/human chimeric antibody cPIPP (IgG1/kappa) a high association rate of k(ass)=1.7 x 10(6) (M s)(-1) and a low dissociation rate of k(diss)=1.8 x 10(-4) s(-1) were observed. The derived dissociation equilibrium constant of K(D)=110 pM was significantly lower than that reported for binding to native FcgammaRI.

MeSH terms

  • Animals
  • Antigen-Antibody Reactions
  • Cell Line
  • Chimera / immunology
  • Chromatography, Affinity
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Immunoglobulin G / immunology*
  • Immunoglobulin G / metabolism*
  • Kinetics
  • Mice
  • Receptors, IgG / immunology*
  • Receptors, IgG / metabolism*
  • Recombinant Proteins / immunology
  • Recombinant Proteins / metabolism
  • Surface Plasmon Resonance


  • Immunoglobulin G
  • Receptors, IgG
  • Recombinant Proteins