Functional assays of membrane-bound proteins with SAMDI-TOF mass spectrometry

(Chemical Equation Presented) Delicate probing: When nanodisc assemblies are used to present membrane proteins on a biochip surface, interactions of these proteins can be studied by mass spectrometry. The method is illustrated with the protein rhodopsin, which is immobilized to a self-assembled monolayer by way of a his-tagged membrane scaffold protein. Upon activation of rhodopsin with light, the protein complex transducin binds and can be detected using SAMDI mass spectrometry.