G-protein linked receptor: Difference between revisions

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G-protein linked receptors, also known as [[G-protein Coupled Receptor|G-protein Coupled receptors]]&nbsp;(GPCR), are a family of receptor signal transducers which are involved in signalling pathways within cells&nbsp;<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg93, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp; Hall in association with the IUBMB</ref>.They can be further divided into to monomeric and trimeric regarding how many &nbsp;components mak up the G-prootein in question.&nbsp;Subtypes, each with an endogenous [[Agonist|agonist]], are involved in maintaining physiological systems such as [[Rhodopsin|rhodopsin]] in [[Rod cells|rod cells]] required for vision&nbsp;<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp; Hall in association with the IUBMB</ref>.<br>  
G-protein linked receptors, also known as [[G-protein Coupled Receptor|G-protein Coupled receptors]]&nbsp;(GPCR), are a family of receptor signal transducers which are involved in signalling pathways within cells&nbsp;<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg93, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp;amp;amp; Hall in association with the IUBMB</ref>.They can be further divided into to monomeric and trimeric regarding how many components make up the G-protein in question.&nbsp;Subtypes, each with an endogenous [[Agonist|agonist]], are involved in maintaining physiological systems such as [[Rhodopsin|rhodopsin]] in [[Rod cells|rod cells]] required for vision&nbsp;<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp;amp;amp; Hall in association with the IUBMB</ref>.&nbsp;<br>  


=== Structure  ===
=== Structure  ===


The structure of these proteins comprises of seven [[Transmembrane helices|transmembrane helices]] with an extracellular ligand binding domain and an intracellular G-protein binding domain&nbsp;<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp; Hall in association with the IUBMB</ref>.<br>  
The structure of these proteins comprises of seven [[Transmembrane helices|transmembrane helices]] with an extracellular ligand binding domain and an intracellular G-protein binding domain&nbsp;<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp;amp;amp; Hall in association with the IUBMB</ref>.<br>  


=== References ===
<br>
 
=== Mechanism  ===
 
== Trimeric G-proteins  ==
 
Ligand will bind to extracellular ligand-binding domain of G-protein coupled receptor. After binding of ligand, receptor undergoes conformational change and activate G-protein. α-subunit undergoes conformation change and causes GDP to dissociate from&nbsp;α-subunit.&nbsp;α-subunit binds GTP and causes further conformational change of G-protein. α subunit and βγ subunits are activated and dissociate. G-protein transduces signals by binding to target protein (eg. [https://teaching.ncl.ac.uk/bms/wiki/index.php/Adenylyl_cyclase adenylyl cyclase], [https://teaching.ncl.ac.uk/bms/wiki/index.php/Phospholipase_C phospholipase C)]. Activated target proteins relay signal to the other components in signalling cascade.&nbsp;α subunit hydrolyses GTP to GDP and inactivate α subunit. Inactivated&nbsp;α subunit reassembles with&nbsp;βγ subunits to reform an inactivate G protein.<br><br>
 
=== References<br> ===


<references />
<references />

Revision as of 13:55, 4 December 2017

G-protein linked receptors, also known as G-protein Coupled receptors (GPCR), are a family of receptor signal transducers which are involved in signalling pathways within cells [1].They can be further divided into to monomeric and trimeric regarding how many components make up the G-protein in question. Subtypes, each with an endogenous agonist, are involved in maintaining physiological systems such as rhodopsin in rod cells required for vision [2]. 

Structure

The structure of these proteins comprises of seven transmembrane helices with an extracellular ligand binding domain and an intracellular G-protein binding domain [3].


Mechanism

Trimeric G-proteins

Ligand will bind to extracellular ligand-binding domain of G-protein coupled receptor. After binding of ligand, receptor undergoes conformational change and activate G-protein. α-subunit undergoes conformation change and causes GDP to dissociate from α-subunit. α-subunit binds GTP and causes further conformational change of G-protein. α subunit and βγ subunits are activated and dissociate. G-protein transduces signals by binding to target protein (eg. adenylyl cyclase, phospholipase C). Activated target proteins relay signal to the other components in signalling cascade. α subunit hydrolyses GTP to GDP and inactivate α subunit. Inactivated α subunit reassembles with βγ subunits to reform an inactivate G protein.

References

  1. ↑ Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg93, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp;amp; Hall in association with the IUBMB
  2. ↑ Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp;amp; Hall in association with the IUBMB
  3. ↑ Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman &amp;amp;amp;amp;amp;amp; Hall in association with the IUBMB
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