title: A novel silk-like shell matrix gene is expressed in the mantle edge of the Pacific oyster prior to shell regeneration.
abstract: During shell formation, little is known about the functions of organic matrices, especially about the biomineralization of shell prismatic layer. We identified a novel gene, shelk2, from the Pacific oyster presumed to be involved in the shell biosynthesis. The Pacific oyster has multiple copies of shelk2. Shelk2 mRNA is specifically expressed on the mantle edge and is induced during shell regeneration, thereby suggesting that Shelk2 is involved in shell biosynthesis. To our surprise, the database search revealed that it encodes a spider silk-like alanine-rich protein. Interestingly, most of the Shelk2 primary structure is composed of two kinds of poly-alanine motifs-GXNA(n)(S) and GSA(n)(S)-where X denotes Gln, Arg or no amino acid. Occurrence of common motifs of Shelk2 and spider silk led us to the assumption that shell and silk are constructed under similar strategies despite of their living environments.
authors.affiliation: Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Takahashi
authors.forename: Masaya
authors.initials: M
authors.lastname: Takagi
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Okihana
authors.forename: Kei
authors.initials: K
authors.lastname: Takeo
authors.forename: Takahisa
authors.initials: T
authors.lastname: Ueda
authors.forename: Ken
authors.initials: K
authors.lastname: Touhata
authors.forename: Shingo
authors.initials: S
authors.lastname: Maegawa
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Toyohara
mesh_terms: D000595:Amino Acid Sequence; D060105:Animal Shells / Q000378:metabolism* / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D008954:Models, Biological; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D010125:Ostreidae / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D012038:Regeneration / Q000235:genetics* / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D047011:Silk / Q000235:genetics* / Q000302:isolation & purification; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D047011:Silk