Quantifying the effects of molecular orientation and length on two-dimensional receptor-ligand binding kinetics

J Biol Chem. 2004 Oct 22;279(43):44915-23. doi: 10.1074/jbc.M407039200. Epub 2004 Aug 6.


Surface presentation of adhesion receptors influences cell adhesion, although the mechanisms underlying these effects are not well understood. We used a micropipette adhesion frequency assay to quantify how the molecular orientation and length of adhesion receptors on the cell membrane affected two-dimensional kinetic rates of interactions with surface ligands. Interactions of P-selectin, E-selectin, and CD16A with their respective ligands or antibody were used to demonstrate such effects. Randomizing the orientation of the adhesion receptor or lowering its ligand- and antibody-binding domain above the cell membrane lowered two-dimensional affinities of the molecular interactions by reducing the forward rates but not the reverse rates. In contrast, the soluble antibody bound with similar three-dimensional affinities to cell-bound P-selectin constructs regardless of their orientation and length. These results demonstrate that the orientation and length of an adhesion receptor influences its rate of encountering and binding a surface ligand but does not subsequently affect the stability of binding.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / chemistry
  • CHO Cells
  • Cell Adhesion
  • Cell Line, Tumor
  • Cricetinae
  • Dose-Response Relationship, Drug
  • E-Selectin / chemistry
  • Erythrocytes / metabolism
  • HL-60 Cells
  • Humans
  • Kinetics
  • Ligands
  • Models, Biological
  • Models, Chemical
  • P-Selectin / chemistry
  • Protein Binding
  • Protein Structure, Tertiary
  • Receptors, IgG / chemistry*
  • Receptors, IgG / metabolism
  • Time Factors


  • Antibodies, Monoclonal
  • E-Selectin
  • Ligands
  • P-Selectin
  • Receptors, IgG