title: Tributyltin-binding protein type 1 has a distinctive lipocalin-like structure and is involved in the excretion of tributyltin in Japanese flounder, Paralichthys olivaceus.
abstract: Tributyltin-binding protein type 1 (TBT-bp1) is a newly discovered protein that binds with TBT in the blood of the Japanese flounder, Paralichthys olivaceus. We determined the genomic sequence of TBT-bp1 and found that this protein has a conserved exon-intron structure that is common to the lipocalin protein family. The secondary and tertiary structures of TBT-bp1, predicted from amino acid sequence, included at least two alpha-helices and eight beta-sheets that are conserved in all lipocalins and form a barrel structure that may bind with ligands. Analysis of the gene structure, secondary structure, and tertiary structure demonstrated that TBT-bp1 could be classified as a lipocalin. A homology search revealed the presence of TBT-bp1-like proteins in eight species of teleost. When flounder were injected intraperitoneally with TBT-d27 at 11.6mug/fish, TBT-d27 was detected in the blood and in the skin mucus. The concentration of TBT-d27 in mucus was approximately 1/100 of that in the serum. Western blotting analysis revealed that TBT-bp1 was present in the skin mucus. These results suggest that TBT-bp1 in Japanese flounder binds with TBT and is excreted from the body via the mucus.
authors.affiliation: Laboratory of Marine Environmental Science, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Hina
authors.initials: H
authors.lastname: Satone
authors.forename: Yuji
authors.initials: Y
authors.lastname: Oshima
authors.forename: Yohei
authors.initials: Y
authors.lastname: Shimasaki
authors.forename: Takahiko
authors.initials: T
authors.lastname: Tawaratsumida
authors.forename: Yumi
authors.initials: Y
authors.lastname: Oba
authors.forename: Eriko
authors.initials: E
authors.lastname: Takahashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kitano
authors.forename: Shun-ichiro
authors.initials: S
authors.lastname: Kawabata
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Kakuta
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Honjo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005432:Flounder / Q000235:genetics / Q000378:metabolism*; D054834:Lipocalins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009093:Mucus / Q000378:metabolism; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D014220:Trialkyltin Compounds / Q000097:blood / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000097:blood / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D029941:Fish Proteins; D054834:Lipocalins; D014220:Trialkyltin Compounds; D014874:Water Pollutants, Chemical; C011559:tributyltin