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Interaction between GABA A receptor subunit intracellular loops: implications for higher order complex formation
Author(s) -
NymannAndersen Jesper,
Wang Hongbing,
Sawyer Gregory W.,
Olsen Richard W.
Publication year - 2002
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2002.01222.x
Subject(s) - protein subunit , cys loop receptors , gamma aminobutyric acid receptor subunit alpha 1 , interleukin 10 receptor, alpha subunit , interleukin 5 receptor alpha subunit , receptor , gaba receptor , inhibitory postsynaptic potential , biochemistry , amino acid , gabaa receptor , biology , chemistry , g alpha subunit , acetylcholine receptor , neuroscience , nicotinic acetylcholine receptor , gene
The majority of fast inhibitory neurotransmission in the CNS is mediated by the GABA type‐A (GABA A ) receptor, a ligand‐gated chloride channel. Of the approximately 20 different subunits composing the hetero‐pentameric GABA A receptor, the γ2 subunit in particular seems to be important in several aspects of GABA A receptor function, including clustering of the receptor at synapses. In this study, we report that the intracellular loop of the γ2 subunit interacts with itself as well as with γ1, γ3 and β1–3 subunits, but not with the α subunits. We further show that γ2 subunits interact with photolabeled pentameric GABA A receptors composed of α1, β2/3 and γ2 subunits, and calculate the dissociation constant to be in the micromolar range. By using deletion constructs of the γ2 subunit in a yeast two‐hybrid assay, we identified a 23‐amino acid motif that mediates self‐association, residues 389–411. We confirmed this interaction motif by inhibiting the interaction in a glutathione‐ S ‐transferase pull‐down assay by adding a corresponding γ2‐derived peptide. Using similar approaches, we identified the interaction motif in the γ2 subunit mediating interaction with the β2 subunit as a 47‐amino acid motif that includes the γ2 self‐interacting motif. The identified γ2 self‐association motif is identical to the interaction motif reported between GABA A receptor and GABA A receptor‐associated protein (GABARAP). We propose a model for GABA A receptor clustering based on GABARAP and GABA A receptor subunit–subunit interaction.