beta-Keratins of the Crocodilian Epidermis: Composition, Structure, and Phylogenetic Relationships
| Autor: | Mattia Toni, Deena Emera, Luisa Dalla Valle, Carlotta Gelmi, Alessia Nardi, Lorenzo Alibardi |
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| Přispěvatelé: | Dalla Valle L, Nardi A, Gelmi C, Toni M, Emera D, Alibardi L |
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
DNA
Complementary Protein Conformation Molecular Sequence Data Biology Complementary DNA Genetics Animals Amino Acid Sequence Cloning Molecular Protein secondary structure Gene In Situ Hybridization Phylogeny Ecology Evolution Behavior and Systematics DNA Primers Genomic organization chemistry.chemical_classification Alligators and Crocodiles Likelihood Functions Base Sequence Models Genetic integumentary system Phylogenetic tree Intron Bayes Theorem Sequence Analysis DNA beta-Keratins Immunohistochemistry Amino acid Blotting Southern genomic DNA chemistry Molecular Medicine Animal Science and Zoology Epidermis Developmental Biology |
| Popis: | Nucleotide and deduced amino acid sequences of three β-keratins of Nile crocodile scales are presented. Using 5′- and 3′-RACE analysis, two cDNA sequences of 1 kb (Cr-gptrp-1) and 1.5 kb (Cr-gptrp-2) were determined, corresponding to 17.4 and 19.3 kDa proteins, respectively, and a pI of 8.0. In genomic DNA amplifications, we determined that the 5′-UTR of Cr-gptrp-2 contains an intron of 621 nucleotides. In addition, we isolated a third gene (Cr-gptrp-3) in genomic DNA amplifications that exhibits seven amino acid differences with Cr-gptrp-2. Genomic organization of the sequenced crocodilian β-keratin genes is similar to avian β-keratin genes. Deduced proteins are rich in glycine, proline, serine, and tyrosine, and contain cysteines toward the N- and C-terminal regions, likely for the formation of disulfide bonds. Prediction of the secondary structure suggests that the central core box of 20 amino acids contains two β-strands and has 75–90% identity with chick β-keratins. Toward the C-terminus, numerous glycine–glycine–tyrosine and glycine–glycine–leucine repeats are present, which may contribute to making crocodile scales hard. In situ hybridization shows expression of β-keratin genes in differentiating β-cells of epidermal transitional layers. Phylogenetic analysis of the available archosaurian and lepidosaurian β-keratins suggests that feather keratins diversified early from nonfeather keratins, deep in archosaur evolution. However, only the complete knowledge of all crocodilian β-keratins will confirm whether feather keratins have an origin independent of those in bird scales, which preceded the split between birds and crocodiles. J Exp Zool (Mol. Dev. Evol.) 312B:42–57, 2009. © 2008 Wiley-Liss, Inc. |
| Databáze: | OpenAIRE |
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