androgen receptor

The androgen receptor is the docking station inside cells that lets androgens give their orders. A hormone is only as good as the receptor that reads it, and this protein is the single reader for both testosterone and DHT, translating their arrival into changes in which genes a cell switches on.

It is an intracellular (nuclear) receptor, meaning it works inside the cell rather than at the surface. When testosterone or DHT enters and binds it, the receptor changes shape, moves into the nucleus, and attaches to specific DNA sequences to turn target genes on or off. DHT binds it more tightly than testosterone, which is why DHT produces a stronger androgenic signal in tissues where it is made.

Because every androgen effect funnels through this one receptor, a fault in the receptor can erase masculinization even when hormone levels are high. In complete androgen insensitivity syndrome, a genetic male produces normal testosterone but the receptor cannot respond, so the body develops along female external lines despite having testes. Drugs that block this receptor (anti-androgens) are likewise used to treat prostate cancer, which depends on androgen signaling to grow.