ABSTRACT
Is a protein, either on the cell’s surface (e.g. the epinephrine receptor) or ■ inside the cell (e.g. the estrogen receptor).
Has properties of selectivity and high affi nity for the drug. ■ Is often there because the body has endogenous ligands ■ * for the receptor (e.g. the body possesses endogenous opioids which bind the receptors for morphine). Is a frequent target of drug designers. ■ Is designed according to its location and function (for example): ■
extracellular receptors have extracellular, intramembrane and ❚ intracellular domains, and bind to drugs and endogenous chemicals that (usually) do not penetrate the cell intracellular receptors are inside the cell and bind to drugs and ❚ endogenous chemicals (e.g. steroids) that penetrate the cell membrane.
