title: Characterization of FIBCD1 as an acetyl group-binding receptor that binds chitin.
abstract: Chitin is a highly acetylated compound and the second most abundant biopolymer in the world next to cellulose. Vertebrates are exposed to chitin both through food ingestion and when infected with parasites, and fungi and chitin modulate the immune response in different directions. We have identified a novel homotetrameric 55-kDa type II transmembrane protein encoded by the FIBCD1 gene and highly expressed in the gastrointestinal tract. The ectodomain of FIBCD1 is characterized by a coiled-coil region, a polycationic region and C-terminal fibrinogen-related domain that by disulfide linkage assembles the protein into tetramers. Functional analysis showed a high-affinity and calcium-dependent binding of acetylated components to the fibrinogen domain, and a function in endocytosis was demonstrated. Screening for ligands revealed that the FIBCD1 is a high-affinity receptor for chitin and chitin fragments. FIBCD1 may play an important role in controlling the exposure of intestine to chitin and chitin fragments, which is of great relevance for the immune defense against parasites and fungi and for immune response modulation.
authors.affiliation: Medical Biotechnology Center, Pathology, University of Southern Denmark, Odense, Denmark. aschlosser@health.sdu.dk
authors.forename: Anders
authors.initials: A
authors.lastname: Schlosser
authors.forename: Theresa
authors.initials: T
authors.lastname: Thomsen
authors.forename: Jesper B
authors.initials: JB
authors.lastname: Moeller
authors.forename: Ole
authors.initials: O
authors.lastname: Nielsen
authors.forename: Ida
authors.initials: I
authors.lastname: Tornøe
authors.forename: Jan
authors.initials: J
authors.lastname: Mollenhauer
authors.forename: Søren K
authors.initials: SK
authors.lastname: Moestrup
authors.forename: Uffe
authors.initials: U
authors.lastname: Holmskov
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D002686:Chitin / Q000378:metabolism*; D004705:Endocytosis; D041981:Gastrointestinal Tract / Q000737:chemistry; D006801:Humans; D008024:Ligands; D008565:Membrane Proteins; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology
chemical_list: C543711:FIBCD1 protein, human; D008024:Ligands; D008565:Membrane Proteins; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D002686:Chitin