Signal transduction refers to the mechanism of initiation of a cellular response after an agonist binds to a receptor. The extracellular signal initiates an intracellular signalling cascade that transfers, transforms, amplifies and then distributes it. The mechanisms of signal transduction include:
Membrane depolarisation induced by the opening of a ligand-gated ion channel: neurotransmitters, amino acids;
Activation of a G-protein (guanidine nucleotide-binding protein): peptides, neurotransmitters, prostaglandins; Synthesis of a second messenger
Cyclic nucleotide: adenosine 3'-5'-monophosphate (cyclic AMP), guanosine 3'-5'-monophosphate (cyclic GMP)
Intermediates of polyphosphoinositide metabolism: diacylglycerol (DAG), inositol-1,4,5-triphosphate (IP3) Calcium ions
A protein phosphorylation cascade that activates or inhibits intracellular enzymes leading to changes in target cell activity.
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