The complete primary structure of human estrogen receptor beta (hER beta) and its heterodimerization with ER alpha in vivo and in vitro.

Human estrogen receptor beta (hER beta) cDNA that encodes the full-length amino acid sequence has been isolated from testis poly(A)+ RNA with the combination of cDNA screening and reverse transcription-PCR. It is composed of a 1590-bp open reading frame and a segment of the 5'- and 3'-untranslated region (UTR) and encodes an additional 53 amino acids in the N-terminal region compared with the previously reported one. Protein interaction between ER alpha and ER beta was demonstrated in vitro by GST pull-down assay and in vivo by immunoprecipitation. Thus, this study indicates that ER alpha and ER beta can interact in vivo, cross-signaling each other.