Information transmission and processing in G-protein-coupled-receptor complexes

Area of Science:

• Biophysics
• Molecular Biology
• Systems Biology

Background:

• G-protein-coupled receptors (GPCRs) are crucial for cellular signaling but their switching mechanisms are not fully understood.
• Understanding the physical principles of GPCR state transitions is essential for deciphering cellular information processing.

Purpose of the Study:

• To develop a general theoretical framework for molecular computation in biological systems.
• To apply this framework to G-protein-coupled receptors (GPCRs) to elucidate their switching mechanisms.
• To identify key parameters governing GPCR state transitions using nonequilibrium thermodynamics.

Main Methods:

• Developed a theoretical model based on nonequilibrium thermodynamics.
• Identified governing parameters for receptor-state transitions: chemical flux and free-energy differences.
• Incorporated reciprocal conformation-fit changes between ligand and receptor.

Main Results:

• Predicted three quasistable GPCR configurations: 'on,' 'off,' and intermediate, optimizing information transmission.
• Demonstrated that active states sustain chemical flux, while inactive states do not.
• Showed phosphatase activity determines 'on'/'off' states, while kinase activity maintains flux.

Conclusions:

• The model provides a generalizable framework for understanding biological switches driven by chemical flux.
• Predictions align with experimental data, suggesting new drug design targets for GPCRs.
• The framework extends beyond GPCRs to other biological switching systems.