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Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers. (Intercellular signals, a non-local form of cell signaling , encompassing both first messengers and second messengers, are classified as autocrine , juxtacrine , paracrine , and ...
Typically the final effect consists in the activation of an ion channel (ligand-gated ion channel) or the initiation of a second messenger system cascade that propagates the signal through the cell. Second messenger systems can amplify or modulate a signal, in which activation of a few receptors results in multiple secondary messengers being ...
The transcriptional factors are activated by the primary messengers, in most cases, due to their function as nuclear receptors for these messengers. The secondary messengers like DAG or Ca 2+ could also induce or repress gene expression, via transcriptional factors. This response is slower than the first because it involves more steps, like ...
cAMP represented in three ways Adenosine triphosphate. Cyclic adenosine monophosphate (cAMP, cyclic AMP, or 3',5'-cyclic adenosine monophosphate) is a second messenger, or cellular signal occurring within cells, that is important in many biological processes. cAMP is a derivative of adenosine triphosphate (ATP) and used for intracellular signal transduction in many different organisms ...
First messengers are the signaling molecules (hormones, neurotransmitters, and paracrine/autocrine agents) that reach the cell from the extracellular fluid and bind to their specific receptors. Second messengers are the substances that enter the cytoplasm and act within the cell to trigger a response.
Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP.Its most likely mechanism of action is activation of intracellular protein kinases in response to the binding of membrane-impermeable peptide hormones to the external cell surface. [1]
The final biological response (e.g. second messenger cascade, muscle-contraction), is only achieved after a significant number of receptors are activated. Affinity is a measure of the tendency of a ligand to bind to its receptor. Efficacy is the measure of the bound ligand to activate its receptor.
Akt resides in the cytosol in an inactive conformation, until the cell is stimulated and it translocates to the plasma membrane. The Akt PH domain has a high affinity for second messenger PI(3,4,5)P 3, binding to it preferentially over other phosphoinositides. [11] Thus PI3K activity is essential for translocation of Akt to the membrane.