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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 ...
cAMP was discovered by Earl Sutherland and Ted Rall in the mid 1950s. cAMP is considered a secondary messenger along with Ca 2+.Sutherland won the Nobel Prize in 1971 for his discovery of the mechanism of action of epinephrine in glycogenolysis, that requires cAMP as secondary messenger.
Thus cAMP is considered a second messenger and PKA a secondary effector. The effector of the G αq/11 pathway is phospholipase C-β (PLCβ), which catalyzes the cleavage of membrane-bound phosphatidylinositol 4,5-bisphosphate (PIP2) into the second messengers inositol (1,4,5) trisphosphate (IP3) and diacylglycerol (DAG).
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.
These include receptor antagonists, neurotransmitters, neurotransmitter reuptake, G protein-coupled receptors, G proteins, second messengers, the enzymes that trigger protein phosphorylation in response to cAMP, and consequent metabolic processes such as glycogenolysis. Prominent examples include (in chronological order of awarding):
Second messenger systems can amplify or modulate a signal, in which activation of a few receptors results in multiple secondary messengers being activated, thereby amplifying the initial signal (the first messenger).
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 ...
Signal transduction is realized by activation of specific receptors and consequent production/delivery of second messengers, such as Ca 2+ or cAMP.These molecules operate as signal transducers, triggering intracellular cascades and in turn amplifying the initial signal. [4]