A BARLEY CDNA CLONE WITH HOMOLOGY TO THE DNA-BINDING DOMAIN OF THE STEROID-HORMONE RECEPTORS

The steroid hormone receptors are members of a superfamily of nuclear receptors that regulate gene expression in response to a ligand in mammals and insects. A cDNA library from barley (Hordeum vulgare) was screened with highly degenerated oligonucleotides corresponding to 11 and 6 amino acids of the highly conserved DNA-binding domain of the steroid hormone receptors. A full length cDNA clone (ES43) was isolated. The sequence of ES43 shows homology to the DNA-binding domain of the estrogen receptor, including three amino acids (Glu(191), Gly(192) and Ala(195)) at conserved positions, which determine the binding specificity of the estrogen receptor to its hormone response element. Additional homologies concerning critical amino acid positions with all members of the nuclear receptor superfamily are also evident.