Characterization of heterotrimeric collagen molecules in a sea-pen (Cnidaria, Octocorallia).
The collagen of a primitive invertebrate, the sea-pen Veretillum Cnidaria, Octocorallia), was studied with respect to its molecular-chain composition. The soft extracellular tissues (mesoglea) were solubilized by limited pepsin proteolysis and the collagen was isolated by selective precipitation at 0.7 M NaCl under acidic conditions. The pepsinized molecules were 260 nm in length, as demonstrated by electron microscope studies of rotary-shadowed molecules and of the segment-long-spacing crystallites obtained by dialysis against ATP. SDS/PAGE of the extract produced two main bands susceptible to bacterial collagenase, designated as the alpha 1 and alpha 2 chain, which were differentiated clearly by their CNBr cleavage products and the higher glycosylation rate of the alpha 2 chain. The latter finding corresponds with the high hydroxylysine content of the alpha 2 chain. The alpha 1/alpha 2 chain ratio observed in SDS/PAGE and the fact that only one peak was obtained by concanavalin-A affinity chromatography of a non-denatured 0.7 M NaCl extract demonstrate the alpha 1 [alpha 2]2 molecular structure of this collagen. These results contrast with data on the structure of other coelenterates (i.e. [alpha]3 for sea anemone collagen molecules and alpha 1 alpha 2 alpha 3 for jellyfish collagen molecules). They are discussed in relation to the evolution of collagen.
Tillet-Barret
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Laboratoire de Cytologie Moléculaire, CNRS UPR 412, Université Claude Bernard, Villeurbanne, France.
Franc
J M
JM
Franc
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S
Garrone
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D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D003094:Collagen / Q000737:chemistry* / Q000648:ultrastructure; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D006829:Hydra / Q000737:chemistry*; D008854:Microscopy, Electron; D010434:Pepsin A / Q000737:chemistry
D000596:Amino Acids; D003094:Collagen; D010434:Pepsin A; D003488:Cyanogen Bromide