Polyclonal (Rabbit) Anti-Estrogen Receptor Beta Antibody (Cat # PA1-310) Steroid receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate hormone. A receptor for estrogen (ER) was first cloned in 1987 and has been shown to be expressed and transcriptionally active in a number of tissues including ovary, testis, prostate and brain. Until recently, only the 'classical' ER (ERa) has been known. However, a new estrogen binding receptor, referred to as ERb, has recently been cloned in rat and humans.

ERb has been shown to be a high affinity estrogen binding protein capable of initiating transcription of genes under the control of estrogen response elements (ERE's). RNA distribution studies have shown ERb is transcribed in human thymus, spleen, ovary and testis as well as rat ovary and prostate. This distribution overlaps with but is not identical to the tissue distribution of ERa RNA. While ERb RNA distribution has been studied, little is know about protein distribution under various hormone conditions. ERb protein distribution may differ from RNA distribution and from ERa protein given the complex and differing activation, dimerization and translocation pathways exhibited by various steroid receptors under various ligand states.

PA1-310 has been shown to react with various cell types in normal and ERa knock-out mice and normal rats. No immunostaining is observed with pre-immune serum and specific staining is eliminated when PA1-310 is pre-incubated with the immunizing peptide (available as PEP-007). It specifically and very efficiently supershifts rat ERb (see figure), while no shift is observed with pre-immune serum. No Western blot cross-reactivity has been observed with ERa expressed in baculovirus (RP-310).