title: Modification-specific proteomics of plasma membrane proteins: identification and characterization of glycosylphosphatidylinositol-anchored proteins released upon phospholipase D treatment.
abstract: Plasma membrane proteins are displayed through diverse mechanisms, including anchoring in the extracellular leaflet via glycosylphosphatidylinositol (GPI) molecules. GPI-anchored membrane proteins (GPI-APs) are a functionally and structurally diverse protein family, and their importance is well-recognized as they are candidate cell surface biomarker molecules with potential diagnostic and therapeutic applications in molecular medicine. GPI-APs have also attracted interest in plant biotechnology because of their role in root development and cell remodeling. Using a shave-and-conquer concept, we demonstrate that phospholipase D (PLD) treatment of human and plant plasma membrane fractions leads to the release of GPI-anchored proteins that were identified and characterized by capillary liquid chromatography and tandem mass spectrometry. In contrast to phospholipase C, the PLD enzyme is not affected by structural heterogeneity of the GPI moiety, making PLD a generally useful reagent for proteomic investigations of GPI-anchored proteins in a variety of cells, tissues, and organisms. A total of 11 human GPI-APs and 35 Arabidopsis thaliana GPI-APs were identified, representing a significant addition to the number of experimentally detected GPI-APs in both species. Computational GPI-AP sequence analysis tools were investigated for the characterization of the identified GPI-APs, and these demonstrated that there is some discrepancy in their efficiency in classification of GPI-APs and the exact assignment of omega-sites. This study highlights the efficiency of an integrative proteomics approach that combines experimental and computational methods to provide the selectivity, specificity, and sensitivity required for characterization of post-translationally modified membrane proteins.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Felix
authors.initials: F
authors.lastname: Elortza
authors.forename: Shabaz
authors.initials: S
authors.lastname: Mohammed
authors.forename: Jakob
authors.initials: J
authors.lastname: Bunkenborg
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Foster
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Nühse
authors.forename: Urs
authors.initials: U
authors.lastname: Brodbeck
authors.forename: Scott C
authors.initials: SC
authors.lastname: Peck
authors.forename: Ole N
authors.initials: ON
authors.lastname: Jensen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000737:chemistry / Q000166:cytology; D002417:Cattle; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism*; D002853:Chromatography, Liquid; D016208:Databases, Factual; D019075:Electrophoresis, Capillary; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D021962:Membrane Microdomains / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis* / Q000378:metabolism; D008969:Molecular Sequence Data; D010739:Phospholipase D / Q000302:isolation & purification / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary; D020543:Proteome / Q000032:analysis; D040901:Proteomics / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014357:Trypsin / Q000494:pharmacology
chemical_list: D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D020543:Proteome; D010739:Phospholipase D; D014357:Trypsin