Second Messenger
An intracellular signaling molecule generated or released in response to receptor activation (the first messenger), which amplifies and propagates the signal within the cell. Major second messenger systems include cyclic AMP, cyclic GMP, inositol trisphosphate, diacylglycerol, and calcium ions. Second messengers enable signal amplification so that activation of a small number of receptors can produce a large cellular response.
示例
- cAMP: generated by adenylyl cyclase, mediates effects of beta-adrenergic agonists
- IP3 and DAG: generated by phospholipase C, mediate alpha-1 adrenergic and muscarinic M1 effects
- Nitric oxide/cGMP: mediates vasodilatory effects of nitroglycerin and sildenafil
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An intracellular signaling molecule generated or released in response to receptor activation (the first messenger), which amplifies and propagates the signal within the cell. Major second messenger systems include cyclic …