receptoreither

Receptoreither is a term occasionally used in bio-pharmacology to describe a hypothetical class of receptors capable of producing distinct cellular responses depending on the ligand that binds. In this usage, a receptoreither would be a single receptor that can couple to different intracellular signaling pathways, effectively acting as a decision point between, for example, G protein–mediated and beta-arrestin–mediated signaling, or between opposing second messenger systems. The term is not part of standard nomenclature and is not widely adopted in peer-reviewed databases; rather it is encountered in discussions of functional selectivity and receptor promiscuity. In practice, researchers would describe such behavior with established concepts like biased agonism or functional selectivity, or specify the coupling partners and downstream readouts.

Origins and scope: The concept stems from observations that some ligands produce qualitatively different signaling outcomes through the same receptor, and that receptors can exhibit plasticity in coupling to G proteins or other transducers. Receptoreither is thus an umbrella label rather than a formal category, with examples drawn from GPCRs that show ligand-dependent bias, or from receptor tyrosine kinases that recruit distinct substrates upon different stimuli. Critics argue the term may obscure mechanistic details and prefer precise language.

Research approaches: Studying a receptoreither involves profiling multiple signaling pathways for a given receptor-ligand pair, calculating bias factors, and using structural methods to map conformational states. Synthetic biology might exploit this concept to engineer receptors with controllable outputs.

See also: biased agonism, functional selectivity, GPCR, receptor heteromer, ligand bias.