situated on the cell
’s plasma membrane and composed of three parts or domains: the extracellular domain, the transmembrane domain and the intracellular domain. As their name indicates, these domains are situated respectively outside of the cell, on the plasma membrane and inside the cell. The association of the extracellular or intracellular domain with a molecule produces a reaction at the other end of the transmembrane protein. The transmembrane receptors play a crucial role in intercellular communications and in signal transmission.