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Opposite effects of KCTD subunit domains on GABA(B) receptor-mediated desensitization

Seddik, Riad and Jungblut, Stefan P. and Silander, Olin K. and Rajalu, Mathieu and Fritzius, Thorsten and Besseyrias, Valérie and Jacquier, Valérie and Fakler, Bernd and Gassmann, Martin and Bettler, Bernhard. (2012) Opposite effects of KCTD subunit domains on GABA(B) receptor-mediated desensitization. The Journal of biological chemistry, Vol. 287, H. 47. pp. 39869-39877.

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Official URL: http://edoc.unibas.ch/dok/A6124477

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Abstract

GABA(B) receptors assemble from principle and auxiliary subunits. The principle subunits GABA(B1) and GABA(B2) form functional heteromeric GABA(B(1,2)) receptors that associate with homotetramers of auxiliary KCTD8, -12, -12b, or -16 (named after their K(+) channel tetramerization domain) subunits. These auxiliary subunits constitute receptor subtypes with distinct functional properties. KCTD12 and -12b generate desensitizing receptor responses while KCTD8 and -16 generate largely non-desensitizing receptor responses. The structural elements of the KCTDs underlying these differences in desensitization are unknown. KCTDs are modular proteins comprising a T1 tetramerization domain, which binds to GABA(B2), and a H1 homology domain. KCTD8 and -16 contain an additional C-terminal H2 homology domain that is not sequence-related to the H1 domains. No functions are known for the H1 and H2 domains. Here we addressed which domains and sequence motifs in KCTD proteins regulate desensitization of the receptor response. We found that the H1 domains in KCTD12 and -12b mediate desensitization through a particular sequence motif, T/NFLEQ, which is not present in the H1 domains of KCTD8 and -16. In addition, the H2 domains in KCTD8 and -16 inhibit desensitization when expressed C-terminal to the H1 domains but not when expressed as a separate protein in trans. Intriguingly, the inhibitory effect of the H2 domain is sequence-independent, suggesting that the H2 domain sterically hinders desensitization by the H1 domain. Evolutionary analysis supports that KCTD12 and -12b evolved desensitizing properties by liberating their H1 domains from antagonistic H2 domains and acquisition of the T/NFLEQ motif.
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Division of Physiology > Molecular Neurobiology Synaptic Plasticity (Bettler)
UniBasel Contributors:Bettler, Bernhard
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Society of Biological Chemists
ISSN:0021-9258
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:08 May 2015 08:45
Deposited On:21 Jun 2013 12:26

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