Identification and Characterization of a Functionally Distinct Form of Human Estrogen Receptor

Estrogen receptors are important for the development and maintenance of many different tissues in the body including the breast, uterus, brain and bone. There are two known genes encoding estrogen receptors, Estrogen Receptor alpha (ERα) and Estrogen Receptor beta (ERβ). These receptors are transcription factors with distinct functional domains involved in DNA binding, ligand binding and transcriptional regulation. A novel isoform of human ERβ (ERβ548) which includes an extended amino terminal domain has been identified. Isoform specific antibodies confirm the presence of this receptor in human tissue. Transactivation analysis with different estrogenic ligands indicates that ERβ548 is functionally distinct from previously reported forms of ERβ.