Second messenger
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In biology, second messengers are low-weight diffusible molecules that are used in signal transduction to relay signals within a cell. They are synthesized or released by specific enzymatic reactions, usually as a result of an external signal that was received by a transmembrane receptor and pre-processed by other membrane-associated proteins. There are three basic types of second messenger molecules:
- Hydrophobic molecules like diacylglycerol, InsP3 and phosphatidylinositols are membrane-associated and diffuse from the plasma membrane into the juxtamembrane space where they can reach and regulate membrane-associated effector proteins.
- Hydrophilic molecules are water-soluble molecules, like cAMP, cGMP, and Ca2+, that are located within the cytosol.
- gases, nitric oxide (NO) and carbon monoxide (CO), that can diffuse both through cytosol and across cellular membranes.
These intracellular messengers have some properties in common:
- They can be synthesized/released and broken down again in specific reactions by enzymes.
- Some (like Ca2+) can be stored in special organelles and quickly released when needed.
- Their production/release and destruction can be localized, enabling the cell to limit space and time of signal activity.
[edit] External links
- Kimball, J. Second Messengers. URL accessed on February 10, 2006.
Cell physiology: cell signaling | |
|---|---|
| Key concepts | Ligand - Cell signaling networks - Signal transduction - Apoptosis - Second messenger system (Ca2+ signaling, Lipid signaling) |
| Processes | Paracrine - Autocrine - Juxtacrine - Neurotransmitters - Endocrine (Neuroendocrine) |
| Types of proteins | Receptor (Transmembrane, Intracellular) - Transcription factor (General, Preinitiation complex, TFIID, TFIIH) - Adaptor protein |
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| This page uses content from the English-language version of Wikipedia. The original article was at Second messenger. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License. |
