Metabotropic receptor

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A metabotropic receptor, also referred to by the broader term

G-protein-coupled receptor, [1] is a type of membrane receptor that initiates a number of metabolic steps to modulate cell activity. The nervous system utilizes two types of receptors: metabotropic and ionotropic receptors. While ionotropic receptors form an ion channel pore, metabotropic receptors are indirectly linked with ion channels through signal transduction mechanisms, such as G proteins
.

Both receptor types are activated by specific

Mechanism

Chemical messengers bind to metabotropic receptors to initiate a diversity of effects caused by biochemical signaling cascades. G protein-coupled receptors are all metabotropic receptors. When a ligand binds to a G protein-coupled receptor, a guanine nucleotide-binding protein, or G protein, activates a second messenger cascade which can alter gene transcription, regulate other proteins in the cell, release intracellular Ca2+, or directly affect ion channels on the membrane.[3][4] These receptors can remain open from seconds to minutes and are associated with long-lasting effects, such as modifying synaptic strength and modulating short- and long-term synaptic plasticity.[5]

Metabotropic receptors have a diversity of ligands, including but not limited to: small molecule transmitters,

GABAB receptors.[2][8]

Structure

The G protein-coupled receptors have seven hydrophobic transmembrane domains. Most of them are monomeric proteins, although GABAB receptors require heterodimerization to function properly. The protein's

N terminus is located on the extracellular side of the membrane and its C terminus is on the intracellular side.[2]

The 7 transmembrane spanning domains, with an external amino terminus, are often claimed as being alpha helix shaped, and the polypeptide chain is said to be composed of around 450–550 amino acids.

References

  1. ^ Purves, Dale, ed. (2018). Neuroscience, 6th ed. Sunderland, Mass: Sinauer Associates. p. 103.
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  4. , retrieved October 30, 2020
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Further reading