Second messenger
From Wikipedia, the free encyclopedia
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
- Second messenger (animation)
- Kimball, J. Second Messengers. Retrieved on February 10, 2006.
| Cell signaling |
|---|
| Key concepts - Ligand | Receptor | Second messenger | Protein kinase | Transcription factor | Cell signaling networks |
| Pathways - Apoptosis | Ca2+ signaling | Cytokine signaling | Hedgehog | Integrin signaling | JAK/STAT | Lipid signaling | MAPK/ERK pathway | mTOR | NF-kB | Notch | p53 | TGFβ | Wnt |
 |
This biochemistry article is a stub. You can help Wikipedia by expanding it. |
