Cell Surface Receptor & Kinase Antibodies

Cell surface receptors transduce signals from the exterior of the cell to the interior by binding to secreted or extracellular factors, including hormones, growth factors, neurotransmitters, or other molecules. Cell surface receptors are generally classified by their tertiary structure or their membrane topology. Cell surface receptors include enzyme-linked receptors, G-protein coupled receptors and ion channel-linked receptors. Transduction of the intracellular signal can be mediated by protein-protein interactions by effector proteins, or by enzymatic activity as in the case of the enzyme-linked receptors. The enzyme-linked receptors usually possess enzymatic activity themselves, or associate with kinases or other enzymatic proteins intracellularly.

Enzyme-linked receptors, which include the receptor tyrosine kinases, are integral membrane proteins with just one transmembrane domain spanning the plasma membrane, and with extracellular and intracellular domains. Upon binding to its ligands or secreted factors they homodimerize or heterodimerize with other members of their receptor family. This promotes conformational changes that induce the tyrosine kinase enzyme activity of the receptor, which then phosphorylates itself and its partner conveying an intracellular signal. The epidermal growth factor receptor (EGFR), the fibroblast growth factor receptor (FGFR) and insulin growth factor receptor (IGFR) are well-known families of tyrosine receptor kinases, which control cellular growth and proliferation and cellular metabolism.

G-protein coupled receptors are seven transmembrane-spanning proteins that can bind hormones, neurotransmitters and other molecules, and are mostly involved in sensory perception. They are coupled intracellularly to G-proteins, which then mediate the signal after receptor and ligand binding. The cyclicAMP receptors, frizzled/smoothened receptors and glutamate receptors are examples of G-protein coupled receptors. Ion channel-linked receptors, also called ligand-gated ion channels or ionotropic receptors, are multipass transmembrane proteins and possess channels for the transport of ions, such as Ca2+, Na+, Cl-, and K+ across membranes. They allow transduction of a fast signal generally induced by neurotransmitters in neurons.