Receptorless

Receptorless is a term used in biology and pharmacology to describe systems, cells, or responses that occur without engagement of a specific receptor for a signaling molecule. It is often used to distinguish effects that require a receptor from those that arise through receptor-independent mechanisms. The concept is particularly relevant in research contexts such as cell biology, genetics, and drug testing, where researchers study whether a given stimulus can elicit a response in the absence of the known receptor.

In practice, receptorless conditions can be achieved by using cells or organisms that lack a receptor through genetic modification, knockout models, or functional inactivation. Researchers may also apply ligands to systems where the receptor has been suppressed to determine if observed effects persist. When responses remain in receptorless models, they are typically attributed to non-receptor pathways, which can include direct interactions with cellular membranes, modulation of ion channels, activation of intracellular enzymes, or other non-canonical targets.

Common considerations include the specificity of the observed effect and the possibility of compensatory pathways or undetected receptor activity. Receptorless studies can illuminate alternative signaling routes and help clarify the mechanisms by which a molecule acts, but they require careful controls to avoid misinterpretation due to incomplete receptor loss, off-target effects, or experimental artifacts.

See also: receptor, signal transduction, knockout, non-receptor mediated signaling.