Tissue Washing Improves Native Ambient Mass Spectrometry Detection of Membrane Proteins Directly from Tissue

Native ambient mass spectrometry enables the in situ analysis of proteins and their complexes directlyfrom tissue, providingboth structural and spatial information. Until recently, the approachwas applied exclusively to the analysis of soluble proteins; however,there is a drive for new techniques that enable analysis of membraneproteins. Here we demonstrate native ambient mass spectrometry ofmembrane proteins, including & beta;-barrel and & alpha;-helical (singleand multipass) integral membrane proteins and membrane-associatedproteins incorporating lipid anchors, by integration of a simple washingprotocol to remove soluble proteins. Mass spectrometry imaging revealedthat washing did not disrupt the spatial distributions of the membraneand membrane-associated proteins. Some delocalization of the remainingsoluble proteins was observed.

Automated summary

Native ambient mass spectrometry allows for in situ analysis of proteins in tissue, providing both structural and spatial information. This study demonstrates the analysis of membrane proteins using this technique, including integral membrane proteins and membrane-associated proteins. The results show that a washing protocol can effectively remove soluble proteins without disrupting the spatial distribution of the membrane proteins.