A receptor is usually a protein or proteinaceous material. It is used for receiving and transducing the signals that are integrated into biological systems. The receptors action can be classified in three main ways:
- Relay of signal
- The receptor is a molecule, usually found on the surface of a cell, that receives chemical signals from outside the cell.
- When such external substances bind to a receptor, they direct the cell to do something, such as divide, die, or allow specific substances to enter or exit the cell.
- Receptors are proteins embedded in either the cell’s plasma membrane (cell surface receptors), in the cytoplasm, or in the cell’s nucleus (nuclear receptors), to which specific signalling molecules may attach.