∞ generated and posted on 2016.12.06 ∞
Specific molecule that when interacting with a signal initiates a signal transduction pathway.
| A Receptor Protein is a cell-associated molecule that either binds to a chemical signal or instead is modified by a physical signal such that the existence of that signal is propagated to the cell and in many cases, particularly within multicellular bodies, to other cells as well. |
Signals can be endogenous or instead exogenous in origin. The may be intentionally produced by cells or instead simply consequences of physiological processes. They can be intentionally provided by entities found outside of bodies (e.g., conspecifics) or instead can be simply a consequences of physical, chemical, or ecological processes that happen to be occurring external to a body. Senses, whether monitoring internal or instead external signals employ receptor proteins, by and large, to detect signals.
Receptor proteins may be located at cell surfaces or within the interior of cells. They may detect hormones or instead keep track of what otherwise is going on in cell's environment. They may be enzymes or serve to relay the occurrence of signal reception in other ways such as by opening up ion channels (e.g., as occurs with neurotransmitter reception by a postsynaptic neuron).
Specific categories of receptor proteins involved in cell-to-cell communication include ion-channel receptors, G protein-linked receptors, and tyrosine-kinase receptors. Note that signals can be ligands, carbohydrates associated for example with glycoproteins, ions, physical changes in the environment, microorganism-associated molecules (i.e., as detected by toll-like receptors), major histocompatibility complexes, etc.
Receptor proteins are often targets for drug action. These drugs either stimulate the receptors upon binding or, instead, block the binding of receptor to normal signals. In this latter case these drugs would be acting more or less equivalently to the action of competitive inhibitors on an enzyme's active site though blocking binding by normal signaling molecules rather than a site of catalysis (which, as an aside, brings up the idea that proteins often have multiple sites where at least the induced fit aspect of active sites is present if not necessarily the catalytic aspect).
Similarly, when you see the word "blocker" in a drug's name, it usually means that the drug binds to a receptor, blocking the ability of the normal signal molecule to initiate signal transduction.