title: Cloning and sequencing of a Porifera partial cDNA coding for a short-chain collagen.
abstract: Collagen is present in Porifera, the lowest multicellular animals, but there is no information available on the primary structure of the collagen chains in this phylum. Developing fresh-water sponges have been used to extract total RNA in order to study in vitro translation products and to construct a cDNA library. Four translated proteins were collagenase-sensitive (200 kDa, 160 kDa, 81 kDa and 48 kDa). The cDNA library was screened with a human collagen probe and a clone, EmC4, covering 1.2 kb was isolated. Nucleotide sequencing of EmC4 revealed a conceptual open reading frame coding for 366 amino acids terminated by a stop codon TGA with 103 nucleotides downstream. The presumed translation product encoded contained several domains: a non-collagenous C-terminal domain of 156 amino acids with 9 cysteines, an uninterrupted collagenous domain of 171 amino acids, a non-collagenous domain of 16 amino acids with 3 cysteines and a probably incomplete N-terminal collagenous domain of 23 amino acids. Comparison with other sequences suggested that this collagen chain might belong to a non-fibrillar collagen family which evolved into several sub-families giving rise to nematode cuticular collagens, and type IV collagens.
authors.affiliation: Department of Experimental Histology, CNRS UPR 412, Claude Bernard University, Villeurbanne, France.
authors.forename: J Y
authors.initials: JY
authors.lastname: Exposito
authors.forename: R
authors.initials: R
authors.lastname: Ouazana
authors.forename: R
authors.initials: R
authors.lastname: Garrone
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002474:Cell-Free System; D003001:Cloning, Molecular; D003094:Collagen / Q000235:genetics*; D004247:DNA / Q000302:isolation & purification*; D004251:DNA Transposable Elements; D008969:Molecular Sequence Data; D011161:Porifera / Q000235:genetics*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000302:isolation & purification*
chemical_list: D004251:DNA Transposable Elements; D012333:RNA, Messenger; D003094:Collagen; D004247:DNA