title: Collagen IX: evidence for a structural association between NC4 domains in cartilage and a novel cleavage site in the alpha 1(IX) chain.
abstract: Collagen IX, a structural component of the extracellular matrix of connective tissues, is synthesized as long and short forms which contain or lack, respectively, a 27 kDa non-collagenous (NC) 4 domain at the N-terminus of the alpha 1(IX) chain of the molecule. The long form occurs in cartilage and developing cornea, but not in vitreous, suggesting a specialized function for the NC4 domain, perhaps by interacting with other macromolecules. To test this hypothesis, embryonic chick cartilage was treated with DTSSP, dissociated with bacterial collagenase, and the NC4-containing DTSSP-cross-linked protein complexes examined and purified. Analysis of cartilage extracts using an anti-NC4 antibody, and of purified NC4-containing complexes, identified a predominant NC4 dimer. A naturally-occurring N-terminal fragment of the alpha 1(IX) chain, whose size is equivalent to the NC4-COL3-NC3 domains of the chain, was identified. Association of collagen IX molecules via NC4 domains and the existence of a cleavage site close to the NC3 domain of the molecule are likely to be of primary importance in the growth and remodeling processes of cartilage, in health and disease.
authors.affiliation: Wellcome Trust Center for Cell-Matrix Research, School of Biological Sciences, University of Manchester, UK.
authors.forename: S P
authors.initials: SP
authors.lastname: Douglas
authors.forename: J M
authors.initials: JM
authors.lastname: Jenkins
authors.forename: K E
authors.initials: KE
authors.lastname: Kadler
mesh_terms: D000818:Animals; D002356:Cartilage / Q000737:chemistry* / Q000378:metabolism; D002642:Chick Embryo; D003094:Collagen / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism; D019281:Dimerization; D007106:Immune Sera / Q000096:biosynthesis / Q000378:metabolism; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D013388:Succinimides / Q000494:pharmacology
chemical_list: D003432:Cross-Linking Reagents; D007106:Immune Sera; D013388:Succinimides; C035759:3,3'-dithiobis(sulfosuccinimidyl propionate); D003094:Collagen