Molecular Cloning of Estrogen Receptors α and β in the Ovary of A Teleost Fish, the Tilapia (Oreochromis niloticus)(Endocrinology)

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Estrogen receptors (ER) in mammals have recently been shown to be encoded by two distinct genes, ERα and ERβ. In this study, cDNAs encoding two tilapia ER subtypes, tER5.1 and tER4.3, were cloned from an ovarian cDNA library of a teleost fish, the tilapia Oreochromis niloticus. The tER5.1 and tER4.3 contain complete open reading frames encoding 585 and 557 amino acid residues, respectively. The two receptors share about 12% homology in the A/B domain, 96% in the DNA binding domain (C domain), 12% in the D domain, 57% in the ligand binding domain (E damain), and 20% in the F domain. Phylogenetic analysis of ER proteins from various vertebrate species indicated that vertebrate ERs consist of two major groups (ERα and ERβ) ; tER5.1 and tER4.3 belong to ERα and ERβ subtypes, respectively. Thus, we consider tER5.1 and tER4.3 to be the tilapia homologs of ERα (tERα) and ERβ (tERβ), respectively. In transient transfection assays using mammalian COS-7 cells, both tERα and tERβ showed estradiol-17β dependent activation of transcription from the estrogen-responsive ERE-Luc promoter. This is the first report of the presence of ERα and ERβ within a single non-mammalian vertebrate species.
社団法人日本動物学会の論文
1999-08-15