Aryl hydrocarbon receptor. A protein within the cell that binds to aryl hydrocarbons forming a complex that moves into the nucleus of the cell. In the nucleus, this complex controls the onset of a series of biotransformation processes for the excretion of hydrocarbon compounds. Ah-receptor binding, may, however also result in the synthesis of other proteins, some of which may interfere adversely with cellular growth and differentiation (specialization).