nuclear receptor

A nuclear receptor is a receptor that lives inside the cell and acts as a switch on the cell's genetic library. When a fat-soluble messenger such as a steroid hormone slips into the cell and binds it, the nuclear receptor turns specific genes on or off. Rather than relaying a fast electrical or chemical pulse, it changes which proteins the cell actually makes.

Once activated by its ligand, a nuclear receptor often travels to the cell nucleus, docks onto a particular stretch of DNA, and recruits the machinery that reads genes into action. This makes it a ligand-activated transcription factor, a protein whose job is to control gene expression in response to a chemical signal. Because the effect is to reprogram protein production, the consequences are typically slower but longer-lasting than those of surface receptors.

Many widely used drugs are designed around nuclear receptors, including anti-inflammatory steroids and several hormonal therapies. The honest caveat is that because a single nuclear receptor can switch many genes simultaneously, its drugs often produce broad effects, and long-term use can carry significant side effects that must be weighed against the benefit.