receptor /risep″tər/ [L, recipere, to receive] , 1. a chemical structure, usually of protein or carbohydrate, on the surface of a cell that combines with an antigen to produce a discrete immunological component. 2. a sensory nerve ending that responds to various kinds of stimulation. 3. a specific cellular protein that must first bind a hormone before cellular response can be elicited. The protein may be in the cytoplasm or in the cell membrane and has a special affinity for toxins and complement-fixing antibodies.
