title: Pleomorphism in type I collagen fibrils produced by persistence of the procollagen N-propeptide.
abstract: The assembly of type I collagen and type I pN-collagen was studied in vitro using a system for generating these molecules enzymatically from their immediate biosynthetic precursors. Collagen generated by C-proteinase digestion of pC-collagen formed D-periodically banded fibrils that were essentially cylindrical (i.e. circular in cross-section). In contrast, pN-collagen generated by C-proteinase digestion of procollagen formed thin, sheet-like structures that were axially D-periodic in longitudinal section, of varying lateral widths (up to several microns) and uniform in thickness (approximately 8 nm). Mixtures of collagen and pN-collagen assembled to form a variety of pleomorphic fibrils. With increasing pN-collagen content, fibril cross-sections were progressively distorted from circular to lobulated to thin and branched structures. Some of these structures were similar to fibrils observed in certain heritable disorders of connective tissue where N-terminal procollagen processing is defective. The observations are considered in terms of the hypothesis that the N-propeptides are preferentially located on the surface of a growing assembly. The implications for normal diameter control of collagen fibrils in vivo are discussed.
authors.affiliation: Department of Biochemistry, University of Edinburgh Medical School, U.K.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hulmes
authors.forename: K E
authors.initials: KE
authors.lastname: Kadler
authors.forename: A P
authors.initials: AP
authors.lastname: Mould
authors.forename: Y
authors.initials: Y
authors.lastname: Hojima
authors.forename: D F
authors.initials: DF
authors.lastname: Holmes
authors.forename: C
authors.initials: C
authors.lastname: Cummings
authors.forename: J A
authors.initials: JA
authors.lastname: Chapman
authors.forename: D J
authors.initials: DJ
authors.lastname: Prockop
mesh_terms: D003094:Collagen / Q000648:ultrastructure*; D003238:Connective Tissue / Q000648:ultrastructure*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D011347:Procollagen / Q000378:metabolism*
chemical_list: D011347:Procollagen; D003094:Collagen