title: Cloning and characterization of scale beta-keratins in the differentiating epidermis of geckoes show they are glycine-proline-serine-rich proteins with a central motif homologous to avian beta-keratins.
abstract: The beta-keratins constitute the hard epidermis and adhesive setae of gecko lizards. Nucleotide and amino acid sequences of beta-keratins in epidermis of gecko lizards were cloned from mRNAs. Specific oligonucleotides were used to amplify by 3'- and 5'-rapid amplification of cDNA ends analyses five specific gecko beta-keratin cDNA sequences. The cDNA coding sequences encoded putative glycine-proline-serine-rich proteins of 16.8-18 kDa containing 169-191 amino acids, especially 17.8-23% glycine, 8.4-14.8% proline, 14.2-18.1% serine. Glycine-rich repeats are localized toward the initial and end regions of the protein, while a central region, rich in proline, has a strand conformation (beta-pleated fold) likely responsible for the formation of beta-keratin filaments. It shows high homology with a core region of other lizard keratins, avian scale, and feather keratins. Northern blotting and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis show a higher beta-keratin gene expression in regenerating epidermis compared with normal epidermis. In situ hybridization confirms that mRNAs for these proteins are expressed in cells of the differentiating oberhautchen cells and beta-cells. Expression in adhesive setae of climbing lamellae was shown by RT-PCR. Southern blotting analysis revealed that the proteins are encoded by a multigene family. PCR analysis showed that the genes are presumably located in tandem along the DNA and are transcribed from the same DNA strand like in avian beta-keratins.
authors.affiliation: Dipartimento di Biologia, Università di Padova, Padova, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Dalla Valle
authors.forename: Alessia
authors.initials: A
authors.lastname: Nardi
authors.forename: Vania
authors.initials: V
authors.lastname: Toffolo
authors.forename: Cristiana
authors.initials: C
authors.lastname: Niero
authors.forename: Mattia
authors.initials: M
authors.lastname: Toni
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Alibardi
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004817:Epidermis / Q000737:chemistry*; D015870:Gene Expression; D005998:Glycine / Q000032:analysis; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008116:Lizards / Q000196:embryology* / Q000235:genetics*; D008969:Molecular Sequence Data; D009841:Oligonucleotides; D011392:Proline / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D012694:Serine / Q000032:analysis; D053800:beta-Keratins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D009841:Oligonucleotides; D053800:beta-Keratins; D012694:Serine; D011392:Proline; D005998:Glycine