Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
Receptor–enzyme complex structures show how receptors start to switch off
The structure of rhodopsin, an archetypal member of the G-protein-coupled family of receptors, in complex with its specific kinase enzyme, reveals the molecular mechanism of the first step of receptor inactivation.
Cell behaviour is regulated by myriad external stimuli that act through specialized receptor proteins at the cell surface. G-protein-coupled receptors (GPCRs) are the largest family of receptors and mediate cellular responses to hormones, neurotransmitter molecules, light and other stimuli by activating G proteins inside cells. This signalling is terminated by a two-step mechanism: G-protein-coupled receptor kinase (GRK) enzymes add phosphate chemical groups to an active receptor, and the active phosphorylated receptor is then bound by arrestin proteins, precluding its further coupling to G proteins. Writing in Nature, Chen et al.1 report the first structure of a GPCR–GRK complex: the light-responsive receptor rhodopsin bound to its specific kinase, GRK1 (also known as rhodopsin kinase).