title: Distinctive binding and structural properties of piscine transthyretin.
abstract: The thyroid hormone binding protein transthyretin (TTR) forms a macromolecular complex with the retinol-specific carrier retinol binding protein (RBP) in the blood of higher vertebrates. Piscine TTR is shown here to exhibit high binding affinity for L-thyroxine and negligible affinity for RBP. The 1.56 A resolution X-ray structure of sea bream TTR, compared with that of human TTR, reveals a high degree of conservation of the thyroid hormone binding sites. In contrast, some amino acid differences in discrete regions of sea bream TTR appear to be responsible for the lack of protein-protein recognition, providing evidence for the crucial role played by a limited number of residues in the interaction between RBP and TTR. Overall, this study makes it possible to draw conclusions on evolutionary relationships for RBPs and TTRs of phylogenetically distant vertebrates.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Parma, Parco Area delle Scienze 23/A, 43100 Parma, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Folli
authors.forename: Nicola
authors.initials: N
authors.lastname: Pasquato
authors.forename: Ileana
authors.initials: I
authors.lastname: Ramazzina
authors.forename: Roberto
authors.initials: R
authors.lastname: Battistutta
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zanotti
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Berni
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002347:Carps; D002645:Chickens; D018360:Crystallography, X-Ray; D005453:Fluorescence; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011228:Prealbumin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012177:Retinol-Binding Proteins / Q000378:metabolism; D021541:Sea Bream; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013974:Thyroxine / Q000378:metabolism
chemical_list: D011228:Prealbumin; D011994:Recombinant Proteins; D012177:Retinol-Binding Proteins; D013974:Thyroxine