Hijacked receptors

Pharmacological receptors are typically defined by their selectivity of ligand recognition, including where appropriate stereoselectivity of interaction. It is increasingly clear that receptors may, in fact, be promiscuous species. This promiscuity arises at several levels of organization: two appear to be of particular importance. A given ligand–receptor complex may couple with different effectors and may generate quite different physiological responses: this is particularly common, although not uniquely so, for G protein-coupled receptors. Or a single receptor may recognize fundamentally different ligands often of significantly different characteristics: a number of viruses gain entry to cells through their interaction at receptors for neurotransmitters, peptides or hormones.