title: Proteomic identification and characterization of secreted N-glycosylated NPC2 following cross-linking of the high-affinity receptor for IgE on mast cells.
abstract: Allergen-mediated cross-linking of the high-affinity receptor for IgE on mast cells triggers the release of diverse preformed and de novo synthesized immunoregulatory mediators that further the allergic response. A proteomic screen applied to the detection of proteins secreted by the model rat mast cell line, RBL-2H3 (rat basophilic leukaemia, subline 2H3.1), led to the identification of the cholesterol-binding glycoprotein, NPC2/RE1 (Niemann-Pick Type C2/epididymal secretory protein 1). Glycosylated NPC2 is secreted early in response to an IgE-mediated stimulus and co-localizes with the lysosomal membrane marker, CD63. NPC2 belongs to the ML (MD-2-related lipid-recognition) protein family (155 members), which includes the Toll-like receptor co-factors, MD-1 and MD-2, and perhaps most interestingly, seven major house dust mite allergens of unknown function (including Der p 2 and Der f 2). Possible role(s) for the protein in the allergic response and future applications of this approach are discussed.
authors.affiliation: Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK. akp13@psu.edu
authors.forename: Ashutosh K
authors.initials: AK
authors.lastname: Pathak
authors.forename: Birgit A
authors.initials: BA
authors.lastname: Helm
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000032:analysis / Q000378:metabolism; D039741:Antigens, Dermatophagoides / Q000276:immunology / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003432:Cross-Linking Reagents / Q000737:chemistry; D030501:Epididymal Secretory Proteins / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D047908:Intracellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D010980:Platelet Membrane Glycoproteins / Q000032:analysis / Q000378:metabolism; D040901:Proteomics; D051381:Rats; D017455:Receptors, IgE / Q000378:metabolism*; D060149:Tetraspanin 30
chemical_list: D015703:Antigens, CD; D039741:Antigens, Dermatophagoides; D002352:Carrier Proteins; C554588:Cd63 protein, rat; D003432:Cross-Linking Reagents; D030501:Epididymal Secretory Proteins; D006023:Glycoproteins; D047908:Intracellular Signaling Peptides and Proteins; C426183:Lcn5 protein, rat; C550214:NPC2 protein, rat; D010980:Platelet Membrane Glycoproteins; D017455:Receptors, IgE; D060149:Tetraspanin 30