Assessing whether single-molecule intramolecular resonance energy transfer can resolve GPCR rate constants

Determine whether single-molecule intramolecular resonance energy transfer measurements applied to G‑protein‑coupled receptors have sufficient resolution to yield reliable estimates of the rate constants in a mechanistic reaction scheme for GPCR activation under agonist stimulation.

Background

The paper emphasizes that GPCR signaling mechanisms, such as those described by the cubic ternary complex framework, involve many parameters related to efficacy, making it difficult to infer agonist affinity and efficacy from downstream cellular responses. Attempts to fit comprehensive kinetic models to experimental data are often over-parameterized and do not yield precise estimates.

To better characterize agonist-induced conformational changes at the receptor level, the authors discuss direct observation approaches, particularly single-molecule intramolecular resonance energy transfer measurements. However, they note uncertainties about the interpretability and capability of these measurements to resolve the underlying kinetic rate constants of GPCR activation.