Receptor (biochemistry)

In <a href="/facts/Biochemistry/fa2pWEBp">biochemistry</a> and <a href="/facts/Pharmacology/4Rx8s7Ie">pharmacology</a>, receptors are chemical structures, composed of <a href="/facts/Protein/Jxmagu3E">protein</a>, that receive and <a href="/facts/Signal_transduction/1bs0Me6w">transduce</a> signals that may be integrated into biological systems. These signals are typically chemical messengers which bind to a receptor and produce <a href="/facts/Physiological_response/BzP6MrTN">physiological responses</a> such as change in the <a href="/facts/Electrophysiology/VPd5VYzm">electrical activity of a cell</a>. For example, <a href="/facts/GABA/vRTeQQUG">GABA</a>, an inhibitory <a href="/facts/Neurotransmitter/LlpYFSU3">neurotransmitter</a>, inhibits electrical activity of neurons by binding to <a href="/facts/GABAA_receptor/6G4rAGb3">GABAA receptors</a>. There are three main ways the action of the receptor can be classified: relay of signal, amplification, or integration. Relaying sends the signal onward, amplification increases the effect of a single <a href="/facts/Ligand_(biochemistry)/44QLL4eU">ligand</a>, and integration allows the signal to be incorporated into another biochemical pathway.
Receptor proteins can be classified by their location. <a href="/facts/Cell_surface_receptors/0YGSjDdL">Cell surface receptors</a>, also known as transmembrane receptors, include <a href="/facts/Ligand-gated_ion_channel/gN9RkNC2">ligand-gated ion channels</a>, <a href="/facts/G_protein-coupled_receptor/0arUMkQc">G protein-coupled receptors</a>, and enzyme-linked <a href="/facts/Hormone_receptor/SgjHFJ3D">hormone receptors</a>. <a href="/facts/Intracellular_receptor/Up8SbQIX">Intracellular receptors</a> are those found inside the cell, and include cytoplasmic receptors and <a href="/facts/Nuclear_receptor/9aYqKxnM">nuclear receptors</a>. A molecule that binds to a receptor is called a <a href="/facts/Ligand_(biochemistry)/44QLL4eU">ligand</a> and can be a protein, <a href="/facts/Peptide/C4ltc7UG">peptide</a> (short protein), or another <a href="/facts/Small_molecule/kbwq3VBn">small molecule</a>, such as a <a href="/facts/Neurotransmitter/LlpYFSU3">neurotransmitter</a>, <a href="/facts/Hormone/WFnBnINJ">hormone</a>, pharmaceutical drug, toxin, <a href="/facts/Calcium-sensing_receptor/z8aIKyEh">calcium ion</a> or parts of the outside of a virus or microbe. An endogenously produced substance that binds to a particular receptor is referred to as its endogenous ligand. E.g. the endogenous ligand for the <a href="/facts/Nicotinic_acetylcholine_receptor/k2s2pPHr">nicotinic acetylcholine receptor</a> is <a href="/facts/Acetylcholine/v1d3wRUd">acetylcholine</a>, but it can also be activated by <a href="/facts/Nicotine/VQ6HcIrY">nicotine</a> and blocked by <a href="/facts/Curare/3mvD3WQ9">curare</a>. Receptors of a particular type are linked to specific cellular biochemical pathways that correspond to the signal. While numerous receptors are found in most cells, each receptor will only bind with ligands of a particular structure. This has been analogously compared to <a href="/facts/Enzyme/DSI1Fh7y">how locks will only accept specifically shaped keys</a>. When a ligand binds to a corresponding receptor, it activates or inhibits the receptor's associated biochemical pathway, which may also be highly specialised.
Receptor proteins can be also classified by the property of the ligands. Such classifications include <a href="/facts/Chemoreceptor/KC6IDxzf">chemoreceptors</a>, <a href="/facts/Mechanoreceptor/rj6j4Nt3">mechanoreceptors</a>, <a href="/facts/Gravitropism/TpLjv6Dc">gravitropic receptors</a>, <a href="/facts/Photoreceptor_protein/xEa6hcY7">photoreceptors</a>, <a href="/facts/Magnetoreception/aPPuKQMx">magnetoreceptors</a> and gasoreceptors.

Receptor (biochemistry) open-in-new

Receptor (biochemistry)