User:Rana Saad/The human GABAb receptor

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This is a default text for your page Human gabab receptor. Click above on edit this page to modify. Be careful with the < and > signs. You may include any references to papers as in: the use of JSmol in Proteopedia ^[1] or to the article describing Jmol ^[2] to the rescue. ---

Contents 1 Introduction 1.1 γ-Aminobutyric acid (GABA) 1.2 GABAb receptors 2 Function 3 structure 3.1 GBR1 and GBR2 subunits structure 3.2 VFT interaction 4 Disease 5 Relevance 6 Structural highlights 7 References

Introduction

γ-Aminobutyric acid (GABA)

GABA is the major inhibitory neurotransmitter in the central nervous system (CNS). It plays a key role in modulating neuronal activity since it binds to specific transmembrane receptors (GABAa,GABAb and GABAc) in the plasma membrane of both pre- and postsynaptic neuronal level.

GABAb receptors

Mammalian GABAb receptor is a class C G-protein coupled receptor^[3]. Its structure is similar to mGluR ligand binding domain. GABAb is central to inhibitory neurotransmission in the brain and so is considered a good candidate for treatments against alcoholism, stress and number of brain diseases^[4].

Function

The GABAb receptor causes the opening of the K+ channels in the postsynaptic membrane, bringing the neuron closer to the equilibrium potential of K+, producing hyperpolarization. As a result the Ca+2 channels in the presynaptic terminal close and neurotransmitter release stops. GABAb can also reduce the activity of adenylyl cyclase and decrease the cell’s conductance to Ca+2

structure

GABAb functions as an obligatory heterodimer subunit of GBR1, which is responsible for ligand-binding. GBR2, on the other hand, is responsible for G protein coupling subunits.

GBR1 and GBR2 subunits structure

Each subunit is a domain of seven-transmembrane helixes, composed of a large extracellular domain - venus flytrap (VFT). VFT contains two lobe-shaped domains: LB1 and LB2, which are connected by three short loops. LB1 and LB2 are αβ-folds composed of central β sheet flanked by an α helix

VFT interaction

Disease

Relevance

Structural highlights

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References

1. ↑ Hanson, R. M., Prilusky, J., Renjian, Z., Nakane, T. and Sussman, J. L. (2013), JSmol and the Next-Generation Web-Based Representation of 3D Molecular Structure as Applied to Proteopedia. Isr. J. Chem., 53:207-216. doi:http://dx.doi.org/10.1002/ijch.201300024
2. ↑ Herraez A. Biomolecules in the computer: Jmol to the rescue. Biochem Mol Biol Educ. 2006 Jul;34(4):255-61. doi: 10.1002/bmb.2006.494034042644. PMID:21638687 doi:10.1002/bmb.2006.494034042644
3. ↑ Stevens RC, Cherezov V, Katritch V, Abagyan R, Kuhn P, Rosen H, Wuthrich K. The GPCR Network: a large-scale collaboration to determine human GPCR structure and function. Nat Rev Drug Discov. 2013 Jan;12(1):25-34. doi: 10.1038/nrd3859. Epub 2012 Dec, 14. PMID:23237917 doi:http://dx.doi.org/10.1038/nrd3859
4. ↑ Addolorato G, Leggio L, Cardone S, Ferrulli A, Gasbarrini G. Role of the GABA(B) receptor system in alcoholism and stress: focus on clinical studies and treatment perspectives. Alcohol. 2009 Nov;43(7):559-63. doi: 10.1016/j.alcohol.2009.09.031. PMID:19913201 doi:http://dx.doi.org/10.1016/j.alcohol.2009.09.031