Navigation Links
Phosphorylation


Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule. Its prominent role in biochemistry is the subject of a very large body of research (the Medline database returns over 100,000 articles on the subject, largely on protein phosphorylation).

Contents

Protein phosphorylation

Function

In eukaryotes, protein phosphorylation is probably the most important regulatory event. Many enzymes and receptors are switched "on" or "off" by phosphorylation and dephosphorylation. Phosphorylation is catalyzed by various specific protein kinases, whereas phosphatases dephosphorylate.

An example of the important role that phosphorylation plays is the p53 tumor suppressor gene, which—when active—stimulates transcription of gene that suppress the cell cycle, even to the extent that it undergoes apoptosis. However, this activity should be limited to situations where the cell is damaged or physiology is disturbed. To this end, the p53 protein is extensively regulated. In fact, p53 contains more than 18 different phosphorylation sites.

Upon the deactivating signal, the protein becomes dephosphorylated again and stops working. This is the mechanism in many forms of signal transduction, for example the way in which incoming light is processed in the light-sensitive cells of the retina.

Signaling networks

The network underlying phosphorylation can be very complex. In some cellular signalling pathways, a protein A phosphorylates B, and B phosphorylates C, but A also phosphorylates C directly, and B can phosphorylate D, which may in turn phosphorylate A.

Types of phosphorylation

See also protein kinase for more details on the different types of phosphorylation

Within a protein, phosphorylation can occur on several amino acids. Phosphorylation on serine is the most common, followed by threonine. Tyrosine phosphorylation is relatively rare. However, since tyrosine phosphorylated proteins are relatively easy to purify using antibodies, tyrosine phosphorylation sites are relatively well understood. Histidine and aspartate phosphorylation occurs in prokaryotes as part of two-component signalling.

Other kinds

ATP, the "high-energy" exchange medium in the cell, is synthesized in the mitochondrion by addition of a third phosphate group to ADP in a process referred to as oxidative phosphorylation. ATP is also synthesized by substrate level phosphorylation during glycolysis. ATP is synthesized at the expense of solar energy by photophosphorylation in the chloroplasts of plant cells.

Phosphorylation of sugars is often the stage of their catabolism. It allows cells to accumulate sugars because the phosphate group prevents the molecules from diffusing back across their transporter.


'"/>


(Date:1/22/2015)... Jan. 9, 2015 Valid S.A. ("Company") (BM&FBOVESPA: VLID3 ON), ... general the State of Washington,s Department ... new enrollment and central issuance system for driver,s licenses and ... The project planning and development will start in January 2015, ...
(Date:1/22/2015)... Showcase, Hall E -   EyeLock Inc. , a market ... showcase its EyeLock ID technology integrated in a 3D printed ... Oak Ridge National Laboratory (ORNL) at the 2015 ... technology is being used to validate the driver and authorize ...
(Date:1/22/2015)... , Jan. 20, 2015 NXT-ID, Inc. (NASDAQ: NXTD ... commerce market, reports on the recent success of the Wocket™ smart wallet ... Wocket smart wallet was named as one of the "11 Hot ... "5 Best Products Launched At CES So Far" by Newseveryday.com and "The ...
Breaking Biology News(10 mins):Valid USA Signs Contract For Washington Driver's License Issuance 2EyeLock Debuts First Iris Authentication Technology Embedded in 3D Printed Automobile 2EyeLock Debuts First Iris Authentication Technology Embedded in 3D Printed Automobile 3CES Response for NXT-ID's Wocket Smart Wallet Kicks Off 2015 2CES Response for NXT-ID's Wocket Smart Wallet Kicks Off 2015 3
... Restoration International (SER) released its May 2008 Briefing ... & Biological Conservation within the Ecosystem Approach at ... the Parties held in Bonn, Germany, May 19-30, ... Ecosystem Approach, as developed by the CBD and ...
... and Technology (NIST) have reported* a new technique to ... centrifuges. Many potential applications for carbon nanotubes depend on ... the most important features of the new technique, say ... to produce industrial quantities of high-quality nanotubes. ...
... of shipments involving regulated radioactive materials used in medicine ... industry experts. Meeting in Rome this week at an ... the Mediterranean region that seeks to ease hardships for ... delivery of beneficial radiation sources. The shipment issues ...
Cached Biology News:Integrating restoration and conservation within the ecosystem approach 2Spin control: New technique sorts nanotubes by length 2Experts tackle shipment issues for beneficial radiation sources 2Experts tackle shipment issues for beneficial radiation sources 3
Other biology definitionOther Tags