Transmembrane proteins on the surface of target cells. When they bind to appropriate extracellular signaling molecules, they are activated and generate a cascade of intracellular signals that alter the behavior of the target cells. Cell-surface receptors are grouped into three classes: (1) receptors that are linked to ion channels, (2) receptors linked to G proteins (q.v.), and (3) receptors linked to enzymes. These enzymes are generally protein kinases (q.v.). See ABC transporters, cellular signal transduction, receptor-mediated endocytosis.
Subjects: Genetics and Genomics.