title: MALDI imaging and in situ identification of integral membrane proteins from rat brain tissue sections.
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.
authors.affiliation: Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Nicklay
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Harris
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Schey
authors.forename: Richard M
authors.initials: RM
authors.lastname: Caprioli
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D057054:Molecular Imaging / Q000379:methods*; D018991:Myelin Proteolipid Protein / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014357:Trypsin / Q000378:metabolism
chemical_list: D018991:Myelin Proteolipid Protein; C047516:Plp1 protein, mouse; D014357:Trypsin