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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 ...
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.
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 gases are produced in the neural cytoplasm and are immediately diffused through the cell membrane into the extracellular fluid and into nearby cells to stimulate production of second messengers. Soluble gas neurotransmitters are difficult to study, as they act rapidly and are immediately broken down, existing for only a few seconds.
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]
Calcium is a ubiquitous second messenger with wide-ranging physiological roles. [2] These include muscle contraction , neuronal transmission (as in an excitatory synapse ), cellular motility (including the movement of flagella and cilia ), fertilization , cell growth (proliferation), neurogenesis , learning and memory as with synaptic ...