Molecular cloning and characterization of reptilian estrogen receptor cDNAs.

cDNAs encoding alligator (caiman), Caiman crocodilus and whiptail lizard, Cnemidophorus uniparens estrogen receptors (ERs) were cloned and sequenced. This is the first report of full-length cDNA sequences for reptilian ERs, to our knowledge. The full-length alligator (caiman) ER cDNA (1764 bp, 587 amino acid residues) shows 68% amino acid homology with the full-length whiptail lizard ER cDNA (1746 bp, 581 amino acid residues). The respective ligand binding E domains have 87 and 83% amino acid homology with human ER while the DNA binding C domains show 100% amino acid homology with the human, rat and chicken forms. When the cDNAs were inserted into the pRc/RSV vector and transfected into HeLa cells with a reporter plasmid, the encoding proteins were confirmed to be functional through the interaction of the receptor-ligand complex with the estrogen responsive element (ERE).