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]] | G-protein linked receptors, also known as [[G-protein Coupled Receptor|G-protein Coupled receptors]] (GPCR), are a family of receptor signal transducers which are involved in signalling pathways within cells<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg93, in Heldin,C. Purton,M and the International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman andHall 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. 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<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and the International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman and Hall in association with the IUBMB</ref>. | ||
=== 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 | 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<ref>Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and the International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman and Hall in association with the IUBMB</ref>. | ||
=== Mechanism === | === Mechanism === | ||
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== Trimeric G-proteins == | == 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 | Ligand will bind to an extracellular ligand-binding domain of G-protein coupled receptor. After binding of the ligand, the receptor undergoes a 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 a 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|adenylyl cyclase]], [[phospholipase C|phospholipase C]]). Activated target proteins relay signal to the other components in the signalling cascade. α subunit hydrolyses GTP to GDP and inactivates α subunit. Inactivated α subunit reassembles with βγ subunits to reform an inactivate G protein.<ref>garlandscience. G-Protein Signaling [Internet]. YouTube. YouTube; 2009 [cited 2017Dec4]. Available from: https://www.youtube.com/watch?v=V_0EcUr_txk#t=2.19446</ref> | ||
=== References | === References === | ||
< | <references /> | ||
Latest revision as of 08:59, 5 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 an extracellular ligand-binding domain of G-protein coupled receptor. After binding of the ligand, the receptor undergoes a 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 a 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 the signalling cascade. α subunit hydrolyses GTP to GDP and inactivates α subunit. Inactivated α subunit reassembles with βγ subunits to reform an inactivate G protein.[4]
References
- ↑ Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg93, in Heldin,C. Purton,M and the International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman andHall in association with the IUBMB
- ↑ Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and the International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman and Hall in association with the IUBMB
- ↑ Cascieri.Fong.Graziano.Tota.Candelore.Strader. (1996) ‘Signaling through G-Protein-coupled Receptors’, pg94, in Heldin,C. Purton,M and the International Union of Biochemistry and Molecular Biology. (ed) Signal Transduction, London: Chapman and Hall in association with the IUBMB
- ↑ garlandscience. G-Protein Signaling [Internet]. YouTube. YouTube; 2009 [cited 2017Dec4]. Available from: https://www.youtube.com/watch?v=V_0EcUr_txk#t=2.19446