Testosterone achieves his effect by binding to his androgen receptor (nuclear). Because testosterone is steroid hormone (derived from cholesterol), it has a possibility to free diffuse through the cell membrane. When testosterone binds, the receptor undergoes a structural change which allows it to move into the cell nucleus and dimerize. Receptor dimer than binds directly to the specific sequence of the DNA called hormone response element (HRE) which results in regulation of gene expression.