Cell surface receptors, also known as transmembrane receptors, are cell surface, membrane-anchored, or integral proteins that bind to external ligand molecules, including cytokine receptors and growth factor receptors. This type of receptor spans the plasma membrane and performs signal transduction, converting an extracellular signal into an intracellular signal.
Cell surface receptors can be divided into three main classes: ion channel-linked receptors, G protein-coupled receptors, enzyme-linked receptors.
Ion channel-linked receptors bind a ligand and open a channel through the membrane that allows specific ions to pass through. To form a channel, this type of cell surface receptor has an extensive memberane spanning region. Ion channel-linked receptors are also key components in the cellular response to toxins and venoms, as well as biological processes that involve rapid changes in cells, such as cardiac, skeletal, and smooth muscle contraction, T cell activation and hormone release.
G protein-coupled receptors are the largest family of cell surface receptors and are structurally and functionally related proteins characterized by seven membrane-spanning α helices.
Enzyme-linked receptors include receptor tyrosine kinases (RTKs), receptor serine/threonine kinases, receptor-like tyrosine phosphatases, histidine kinase associated receptors and receptor guanylyl cyclases. Disorders of cell growth, proliferation, differentiation, survival and migration are fundamental to cancer, and abnormalities in signalling via enzyme-linked receptors have a major role in the development of this class of diseases.