Activation function 1 domain plays a negative role in dimerization of estrogen receptor beta

Transcriptional potential of estrogen receptor beta (ERβ) depends on the ligand binding and subsequent dimerization of the receptor protein. In order to examine the role of N-terminally located activation function 1 (AF-1) protein domain in the dimerization process of ERβ, we used yeast SOS-Recruitment System (SRS). Two variants of ERβ protein were expressed in the yeast cells: full length receptor and a truncated form, lacking AF-1. We observed that upon 17β-estradiol treatment only the shorter form of the receptor dimerized, whereas the full-length one did not. This result suggests an inhibitory function of AF-1 in dimer formation and supports previous studies showing that N-terminal domain of ERβ suppresses transcriptional activity.