Native mass spectrometry reveals the simultaneous binding of lipids and zinc to rhodopsin

Rhodopsin, a prototypical G-protein-coupled receptor, is responsible for scoptic vision at low-light levels. Although rhodopsin’s photoactivation cascade is well understood, it remains unclear how lipid and zinc binding to the receptor are coupled. Using native mass spectrometry, we developed a novel data analysis strategy to deconvolve zinc and lipid bound to the proteoforms of rhodopsin and investigated the allosteric interaction between lipids and zinc binding. We discovered that phosphatidylcholine bound to rhodopsin with a greater affinity than phosphatidylserine or phosphatidylethanolamine, and that binding of all lipids was influenced by zinc but with different effects. In contrast, zinc binding was relatively unperturbed by lipids. Overall, these data reveal that lipid binding can be strongly and differentially influenced by metal ions. [Display omitted] •Native MS was used to study lipid and zinc binding to bovine rhodopsin.•Novel double deconvolution data processing was introduced.•Zinc binding was relatively unperturbed by lipid binding.•Lipid binding was significantly influenced by zinc in different ways.