A novel human estrogen receptor β: identification and functional analysis of additional N-terminal amino acids

Abstract

A novel human estrogen receptor β (hER β) was cloned from human testis mRNA, ovary and thymus cDNA utilizing PCR and 5′ RACE methods. The 5′ end of hER β contained an additional open reading frame, in-frame and upstream of the published clones. hER β encodes a protein of 530 amino acids with an approximate molecular weight of 63 kDa and is larger than the previously reported rat, mouse and human protein. To determine the functional role of additional N-terminal amino acids, we compared the transcription functions of receptor lacking (hER β T) and receptor containing (hER β L) this N-terminal extension. hER β L is more active than hER β T in transactivating ERE-based reporter genes. hER β L, but not hER β T, attenuated cytokine mediated NF κB activation. Taken together, the additional N-terminal amino acids appear to play a role in modulating estrogen responsive gene expression in vitro.