receptorreserv

Receptorreserv is a term used in pharmacology and cell signaling to denote a hypothesized pool of receptors that are kept in reserve and can be mobilized to amplify receptor-mediated responses. In this view, the maximal cellular response can be achieved before all receptors are occupied, because only a subset of available receptors is required to trigger the full signaling cascade.

The concept is closely related to the long-established idea of receptor reserve or spare receptors. In systems described as receptorreserv-containing, a fraction of total receptors can produce the maximal response, allowing high potency ligands to evoke full efficacy at submaximal receptor occupancy. This can help explain why some drugs with modest receptor occupancy achieve near-maximal effects.

Mechanisms proposed to underlie receptorreserv include receptor compartmentalization or rapid cycling, high-efficiency coupling to intracellular signaling partners (such as G proteins), allosteric modulation that enhances signal flow, and rapid receptor synthesis that replenishes functional receptors after internalization.

Evidence for receptorreserv typically comes from dose–response analyses showing maximal efficacy before complete receptor occupancy, or from experiments that decrease receptor numbers without reducing the maximal response. Methods used to study this concept include irreversible antagonists, radioligand binding assays, and single-cell imaging of signaling events.

In practice, receptorreserv has implications for drug development and interpretation of efficacy versus potency. It helps account for why some ligands achieve full effects at lower receptor occupancy and relates to phenomena such as partial agonism and tolerance. Some researchers, however, debate its relevance across tissues and in vivo, noting that observed amplification may reflect signaling dynamics rather than an actual reserve of receptors.