Science
Receptor selectivity and assay interpretation
Why affinity, functional potency and biased signalling require different measurements.
A binding assay examines interaction with a receptor under specified conditions. A functional assay examines a downstream cellular response. Because they…
02The system shapes the resultReceptor density, coupling efficiency and readout dynamic range can shift the observed curve. Selectivity should therefore be reported with the expression…
03Comparing with fitness for purposeTo compare three receptors, the procedure needs adequate sensitivity and repeatability in each system. Controls and system-suitability criteria should be set…
Binding and function
A binding assay examines interaction with a receptor under specified conditions. A functional assay examines a downstream cellular response. Because they measure different events, they should not be treated as interchangeable evidence.
The system shapes the result
Receptor density, coupling efficiency and readout dynamic range can shift the observed curve. Selectivity should therefore be reported with the expression system, incubation time, reference agonist and normalisation method.
Comparing with fitness for purpose
To compare three receptors, the procedure needs adequate sensitivity and repeatability in each system. Controls and system-suitability criteria should be set before analysis. Validation is always linked to the intended purpose.
LABORATORY APPLICATION
Turning the principle into an auditable record
Report affinity, functional potency and maximum response separately. Include a reference agonist, negative control, cell description, incubation time and fitting model. If biased signalling is examined, multiple pathways and an appropriate quantitative framework are required; one readout is not enough.
PRIMARY & OFFICIAL SOURCES
Sources and further reading
COMMON QUESTIONS
Questions specific to this topic
What is functional selectivity?
It is a molecule’s relative response across receptors or pathways within a defined assay system.
Why does receptor density matter?
It can change signal amplification and apparent potency or maximum response.
When is a method fit for purpose?
When its documented performance is adequate for the specific question and intended decision.