title: Distinct maturations of N-propeptide domains in fibrillar procollagen molecules involved in the formation of heterotypic fibrils in adult sea urchin collagenous tissues.
abstract: We have characterized the primary structure of a new sea urchin fibrillar collagen, the 5alpha chain, including nine repeats of the sea urchin fibrillar module in its N-propeptide. By Western blot and immunofluorescence analyses, we have shown that 5alpha is co-localized in adult collagenous ligaments with the 2alpha fibrillar collagen chain and fibrosurfin, two other extracellular matrix proteins possessing sea urchin fibrillar modules. At the ultrastructural level, the 5alpha N-propeptide is detected at the surface of fibrils, suggesting the retention of this domain in mature collagen molecules. Biochemical characterization of pepsinized collagen molecules extracted from the test tissue (the endoskeleton) together with a matrix-assisted laser desorption ionization time-of-flight analysis allowed us to determine that 5alpha is a quantitatively minor fibrillar collagen chain in comparison with the 1alpha and 2alpha chains. Moreover, 5alpha forms heterotrimeric molecules with two 1alpha chains. Hence, as in vertebrates, sea urchin collagen fibrils are made up of quantitatively major and minor fibrillar molecules undergoing distinct maturation of their N-propeptide regions and participating in the formation of heterotypic fibrils.
authors.affiliation: Institut de Biologie et Chimie des Protéines, CNRS, Unité Mixte de Recherche 5086, Université Claude Bernard, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Cluzel
authors.forename: Claire
authors.initials: C
authors.lastname: Lethias
authors.forename: Robert
authors.initials: R
authors.lastname: Garrone
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Exposito
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D003094:Collagen / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000737:chemistry; D007525:Isoelectric Focusing; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010434:Pepsin A / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011347:Procollagen / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012617:Sea Urchins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D010455:Peptides; D011347:Procollagen; C429545:fibrosurfin; D003094:Collagen; D004247:DNA; D010434:Pepsin A