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Co-immunoprecipitation Assay for Studying Functional Interactions Between Receptors and Enzymes
Published on: September 28, 2018
Structure and interactions of the human programmed cell death 1 receptor
Xiaoxiao Cheng1, Vaclav Veverka, Anand Radhakrishnan
1Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DU, United Kingdom.
The Journal of Biological Chemistry
|February 19, 2013
Summary
The study reveals the structure of human PD-1 and its interactions with PD-L1 and PD-L2. Despite weak binding affinities, these interactions regulate immune responses, offering insights for immunotherapy development.
Area of Science:
- Immunology
- Structural Biology
- Biophysics
Background:
- Programmed cell death protein 1 (PD-1) is a key immune checkpoint receptor.
- Understanding PD-1's structure and ligand interactions is crucial for immunotherapy.
- Current knowledge of human PD-1 structure and binding is incomplete.
Purpose of the Study:
- To determine the solution NMR structure of the human PD-1 extracellular region.
- To analyze the interactions of human PD-1 with its ligands, PD-L1 and PD-L2.
- To elucidate the biophysical mechanisms governing these interactions and their functional implications.
Main Methods:
- Solution nuclear magnetic resonance (NMR) spectroscopy for structure determination.
- Surface plasmon resonance (SPR) for measuring binding affinities.
- Isothermal titration calorimetry (ITC) for characterizing binding thermodynamics.
- Mathematical simulations for quantitative analysis of biological interactions.
Main Results:
- The solution NMR structure of human PD-1 reveals unique features, including a flexible GFCC' sheet.
- PD-1 interacts differently with PD-L1 and PD-L2, diverging from crystal structures of mouse complexes.
- Binding affinities are weaker than anticipated, with PD-L2 showing higher affinity than PD-L1.
- PD-1/PD-L1 interaction is entropically driven, while PD-1/PD-L2 binding is enthalpically driven.
- PD-L2's contribution to PD-1 ligation in T cell interactions is unexpectedly limited.
Conclusions:
- Provides a detailed structural and biophysical characterization of human PD-1 and its ligand interactions.
- Suggests that potent immune inhibitory signaling can be mediated by weak receptor-ligand interactions.
- Offers a framework for understanding PD-1 function and developing targeted immunotherapies.
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