G-protein linked receptor

From The School of Biomedical Sciences Wiki
Revision as of 08:59, 5 December 2017 by Nnjm2 (Talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

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].

Contents

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

  1. 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
  2. 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
  3. 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
  4. garlandscience. G-Protein Signaling [Internet]. YouTube. YouTube; 2009 [cited 2017Dec4]. Available from: https://www.youtube.com/watch?v=V_0EcUr_txk#t=2.19446
Personal tools
Namespaces
Variants
Actions
Navigation
Toolbox