Structural characteristics of cross-linking sites in type V collagen of bone. Chain specificities and heterotypic links to type I collagen.
To understand the role of type V collagen and its spatial interrelationship with type I collagen in bone matrix, the molecule's covalent intermolecular cross-links were structurally characterized. Type V collagen containing alpha 1(V), alpha 2(V) and alpha 1(XI) chains was isolated from bovine bone and reacted with NaB3H4 to label the cross-linking residues. Radiolabeled native molecules and isolated alpha chains were treated with sodium metaperiodate to cleave the divalent cross-linking bonds. Sequence analysis of the periodate-released peptides matched two of them to alpha 1(V) and alpha 1(XI) aminopropeptide domains. A third peptide was derived from the alpha 1(I) carboxytelopeptide domain of type I collagen. This latter peptide, therefore, came from a site of heterotypic cross-linking between types I and V collagens and accounted for about 15% of the total cross-linked peptides. Sequence analysis of isolated cross-linked tryptic peptides defined the helical sites of attachment of the periodate-released telopeptides and revealed that the putative aminoproteinase-cleavage sites in the alpha 1(V) and alpha 1(XI) chains are located in the molecule interior to the cross-linking residue. These data imply that type V collagen molecules in the extracellular matrix are primarily cross-linked to each other in a head-to-tail linear polymer that is linked laterally to type I collagen molecules in copolymeric fibrils.
Niyibizi
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Department of Orthopaedics, University of Washington, Seattle.
Eyre
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D000595:Amino Acid Sequence; D000818:Animals; D001842:Bone and Bones / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D003094:Collagen / Q000737:chemistry* / Q000378:metabolism; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010504:Periodic Acid; D011485:Protein Binding
D010446:Peptide Fragments; D010504:Periodic Acid; D003094:Collagen