ABSTRACT
The (cell surface) receptor concept answers the question of how information can be transmitted to the cell: receptors are “small, discrete (protein) area(s) on the cell membrane or within the cell with which molecules or molecular complexes (e.g., hormones, drugs, and other chemical messengers) interact.” The origins of the receptor concept date back to the 1878 when Paul Ehrlich and John Newport Langley rst mentioned the idea. The receptor concept was initially based on biological response data and, subsequently, on radio ligand-binding properties. The development of receptor characterization began with receptors that mediate response by coupling to G-proteins, also known as G protein-coupled receptors (GPCRs; cf. following).
