title: The insoluble TGFBIp fraction of the cornea is covalently linked via a disulfide bond to type XII collagen.
abstract: TGFBIp, also known as keratoepithelin and βig-h3, is among the most abundant proteins in the human cornea, and approximately 60% is associated with the insoluble fraction following extraction in sodium dodecyl sulfate (SDS) sample buffer. TGFBIp is of particular interest because a wide range of mutations causes amyloid or fuchsinophilic crystalloid deposits in the cornea leading to visual impairment. We show that the SDS-insoluble fraction of TGFBIp from porcine and human corneas is covalently linked via a reducible bond to the NC3 domain of type XII collagen in a TGFBIp:type XII collagen stoichiometric ratio of 2:1. Because type XII collagen is anchored to striated collagen fibers of the extracellular matrix, its interaction with TGFBIp is likely to provide anchoring for cells to the extracellular matrix through the integrin binding capability of TGFBIp. Furthermore, the TGFBIp-type XII collagen molecule will affect our understanding of the molecular pathogenesis of the TGFBI-linked corneal dystrophies.
authors.affiliation: Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center at the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Runager
authors.forename: Gordon K
authors.initials: GK
authors.lastname: Klintworth
authors.forename: Henrik
authors.initials: H
authors.lastname: Karring
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Enghild
mesh_terms: D000818:Animals; D024082:Collagen Type XII / Q000737:chemistry* / Q000378:metabolism*; D003315:Cornea / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D013552:Swine; D016212:Transforming Growth Factor beta / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000099222:betaIG-H3 Protein
chemical_list: D024082:Collagen Type XII; D004220:Disulfides; D016326:Extracellular Matrix Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein
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