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Ligands for murine NKG2D display heterogeneous binding behavior.
Leonidas N Carayannopoulos1, Olga V Naidenko, Jeremy Kinder
1Barnes-Jewish Hospital, Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
European Journal of Immunology
|February 22, 2002
Summary
Natural killer group 2D (NKG2D) receptor interactions vary. RAE-1B6 and H60 ligands bind murine NKG2D with high affinity, while RAE-1 delta shows lower affinity due to faster dissociation.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Natural killer group 2D (NKG2D) is a receptor on immune cells like natural killer (NK) cells.
- NKG2D signaling enhances immune responses, including cell proliferation, cytokine release, and target cell killing.
- Murine and human NKG2D receptors bind to specific class I-related molecules, known as ligands.
Purpose of the Study:
- To investigate the binding kinetics and affinities of murine NKG2D to its cognate ligands.
- To compare the binding characteristics of different RAE-1 variants (RAE-1B6, RAE-1 delta) and H60 ligand.
Main Methods:
- Surface plasmon resonance (SPR) was employed to quantitatively analyze the binding interactions.
- Kinetic parameters, including dissociation constant (K(D)) and dissociation rate (k(off)), were determined.
Main Results:
- RAE-1B6 and H60 ligands exhibited high-affinity binding to murine NKG2D (K(D) in the 20-30 nM range, t(1/2) approximately 10-20s).
- RAE-1 delta displayed significantly lower affinity (K(D) approximately 750 nM) with faster dissociation kinetics (t(1/2) approximately 3s).
- Despite low sequence identity (20%), H60 and RAE-1B6 showed similar binding kinetics, whereas RAE-1 variants with high sequence identity (90%) exhibited varied affinities.
Conclusions:
- Murine NKG2D exhibits differential binding affinities for its ligands, influenced by specific variants.
- RAE-1B6 serves as a high-affinity ligand for NKG2D in C57BL/6J mice, compensating for the absence of H60.
- Ligand structure and sequence identity do not solely dictate NKG2D binding affinity, highlighting complex molecular recognition mechanisms.