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Updated: May 10, 2026
Sublimation of DAN Matrix for the Detection and Visualization of Gangliosides in Rat Brain Tissue for MALDI Imaging Mass Spectrometry
Published on: March 23, 2017
MALDI imaging and in situ identification of integral membrane proteins from rat brain tissue sections
Joshua J Nicklay1, Glenn A Harris, Kevin L Schey
1Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States.
Abstract:
Transmembrane proteins are greatly underrepresented in data generated by imaging mass spectrometry (IMS) because of analytical challenges related to their size and solubility. Here, we present the first example of MALDI IMS of two highly modified multitransmembrane domain proteins, myelin proteolipid protein (PLP, 30 kDa) and DM-20 (26 kDa), from various regions of rat brain, namely, the cerebrum, cerebellum, and medulla. We utilize a novel tissue pretreatment aimed at transmembrane protein enrichment to show the in situ distribution of fatty acylation of these proteins, particularly of post-translational palmitoylation. Additionally, we demonstrate the utility of protease-encapsulated hydrogels for spatially localized on-tissue protein digestion and peptide extraction for subsequent direct coupling to LC-MS/MS for protein identification.
Insights
This study introduces a new method for analyzing transmembrane proteins using MALDI imaging mass spectrometry (IMS). The technique enhances the detection of fatty acylation, like palmitoylation, in brain proteins.
Area of Science:
- Proteomics
- Neuroscience
- Analytical Chemistry
Background:
- Transmembrane proteins are challenging to analyze with imaging mass spectrometry (IMS) due to their size and solubility.
- Existing IMS methods often underrepresent these crucial proteins.
Purpose of the Study:
- To present the first MALDI IMS analysis of multitransmembrane proteins (PLP and DM-20) in rat brain regions.
- To demonstrate a novel tissue pretreatment for transmembrane protein enrichment.
- To visualize in situ fatty acylation, including palmitoylation, of these proteins.
Main Methods:
- Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS).
- Novel tissue pretreatment for transmembrane protein enrichment.
- Protease-encapsulated hydrogels for on-tissue digestion.
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for protein identification.
Main Results:
- Successfully performed MALDI IMS on myelin proteolipid protein (PLP) and DM-20 in rat cerebrum, cerebellum, and medulla.
- Demonstrated in situ distribution of fatty acylation, specifically post-translational palmitoylation.
- Showcased spatially localized on-tissue protein digestion and peptide extraction using protease-encapsulated hydrogels.
Conclusions:
- The developed MALDI IMS method with novel pretreatment enables the analysis of challenging transmembrane proteins.
- This approach provides insights into the in situ distribution of protein modifications like palmitoylation in the brain.
- Protease-encapsulated hydrogels offer a promising tool for subsequent LC-MS/MS analysis and protein identification.
