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An ELISA Based Binding and Competition Method to Rapidly Determine Ligand-receptor Interactions
Published on: March 14, 2016
Receptor binding kinetics of human IL-3 variants with altered proliferative activity
B K Klein1, J J Shieh, E Grabbe
1Pharmacia Discovery Research, Mail Zone AA4G, 700 Chesterfield Parkway North, St. Louis, MO 63198-0001, USA. barbara.k.klein@Pharmacia.com
Biochemical and Biophysical Research Communications
|November 9, 2001
Summary
Interleukin-3 (IL-3) binding to its receptor (IL-3Ralpha) is crucial for cell proliferation. Amino acid substitutions and truncations significantly alter IL-3 binding kinetics, impacting cell signaling pathways like STAT5 phosphorylation.
Area of Science:
- Biochemistry
- Molecular Biology
- Immunology
Background:
- Interleukin-3 (IL-3) is a cytokine essential for hematopoietic cell proliferation.
- IL-3 exerts its function by binding to the alpha subunit of the IL-3 receptor (IL-3Ralpha).
- Previous studies identified IL-3 variants with altered cell proliferation capacity due to amino acid substitutions.
Purpose of the Study:
- To investigate the binding kinetics of native IL-3 and its variants to IL-3Ralpha.
- To determine the impact of specific amino acid substitutions and truncations on IL-3/IL-3Ralpha interactions.
- To correlate binding characteristics with intracellular signaling events.
Main Methods:
- Surface plasmon resonance (SPR) was employed to measure binding kinetics (association and dissociation rates).
- Site-directed mutagenesis was used to create IL-3 variants with specific amino acid substitutions.
- STAT5 phosphorylation was assessed via intracellular signaling studies.
Main Results:
- Variants E43N and F113Y showed >100-fold slower association rates, indicating residues 43 and 113 are critical for binding.
- Variants G42A, G42D, Q45V, D46S, K116V, and K116W exhibited faster association (up to 15-fold) and slower dissociation (up to 7-fold) rates.
- Altered binding kinetics correlated with changes in the magnitude and kinetics of STAT5 phosphorylation.
Conclusions:
- Both IL-3 truncation and specific amino acid substitutions significantly modulate IL-3 binding kinetics to IL-3Ralpha.
- Residues 43 and 113 are essential for high-affinity IL-3 binding.
- Changes in IL-3/IL-3Ralpha binding directly influence downstream intracellular signaling pathways, such as STAT5 activation.
