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Secondary messenger systems can be synthesized and activated by enzymes, for example, the cyclases that synthesize cyclic nucleotides, or by opening of ion channels to allow influx of metal ions, for example Ca 2+ signaling. These small molecules bind and activate protein kinases, ion channels, and other proteins, thus continuing the signaling ...
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 ...
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.
Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a second messenger signaling cascade that induces a broad, long-lasting signal.
An example would be the coagulation cascade of secondary hemostasis which leads to fibrin formation, and thus, the initiation of blood coagulation. Another example, sonic hedgehog signaling pathway , is one of the key regulators of embryonic development and is present in all bilaterians . [ 2 ]
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.
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events.Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. [1]
When a second messenger system is activated, it starts a cascade of molecular interactions inside the target cell, which may ultimately produce a wide variety of complex effects, such as increasing or decreasing the sensitivity of the cell to stimuli, or even altering gene transcription.