Probing Heterogeneous Lipid Interactions with Membrane Proteins Using Mass Spectrometry.

Native mass spectrometry (Native MS) enables the detection of intact membrane protein complexes in the gas phase. Membrane proteins are encapsulated in nonionic detergent micelles that protect them during transfer into the gas phase and preserves structure and noncovalent interactions. Herein, we describe methods to gently transfer membrane protein complexes bound to a mixture of heterogeneous lipid species into the gas phase. Through careful titrations, equilibrium dissociation constants can be directly determined to elucidate lipid interactions that induce positive, neutral, or negative allostery. These methods can lead to the identification of lipids that modulate membrane protein structure and function.