Androgen effects on the solubility and conformational change of the androgen receptor in baculovirus expression system

To purify the androgen receptor (AR) efficiently from baculovirus expressio n system, we fused 6 histidine residues with the N-terminal domain of AR as a tag to specifically bind to Ni+2-affinity column. Our data indicated tha t adding androgen can increase the binding capacity of his-tag AR to the Ni +2-affinity column, and this increased binding capacity of AR could be due to the exposure of histidine residues of N-terminal domain induced by andro gen. The androgen-enhanced binding to Ni+2-column also correlated with the increasing solubility of AR. Electrophoretic mobility shift assay further i ndicated that only purified AR could interact with androgen response elemen t. Together, our data suggest that the binding of androgen to the hormone b inding domain of AR may result in the conformational change of the N-termin al domain of AR and increase the hydrophilic property of AR.