دورية
Mutations within the agonist-binding site convert the homomeric α1glycine receptor into a Zn2+-activated chloride channel
العنوان: | Mutations within the agonist-binding site convert the homomeric α1glycine receptor into a Zn2+-activated chloride channel |
---|---|
المؤلفون: | Grudzinska, Joanna, Schumann, Tanja, Schemm, Rudolf, Betz, Heinrich, Laube, Bodo |
المصدر: | Channels; January 2008, Vol. 2 Issue: 1 p13-18, 6p |
مستخلص: | The divalent cation Zn2+has been shown to regulate inhibitory neurotransmission in the mammalian CNS by affecting the activation of the strychnine-sensitive glycine receptor (GlyR). In spinal neurons and cells expressing recombinant GlyRs, low micromolar (10 µM) have an inhibitory effect. Mutational studies have localized the Zn2+binding sites mediating allosteric potentiation and inhibition of GlyRs in distinct regions of the N-terminal extracellular domain of the GlyR α-subunits. Here, we examined the ZZn2+sensitivity of different mutations within the agonist binding site of the homomeric α1-subunit GlyR upon heterologous expression in Xenopus oocytes. This revealed that 6 substitutions within the ligand-binding pocket result in a total loss of Zn2+inhibition. Furthermore, substitution of the positively charged residues arginine 65 and arginine 131 by alanine (α1R65A, α1R131A), or of the aromatic residue phenylalanine 207 by histidine (α1F207H), converted the α1 GlyR into a chloride channel that was activated by Zn2+alone. Dose-response analysis of the α1F207H GlyR disclosed an EC50 value of 1.2 µM for Zn2+activation; concomitantly the apparent glycine affinity was 1000-fold reduced. Thus, single point mutations within the agonist-binding site of the α1 subunit convert the inhibitory GlyR from a glycine-gated into a selectively Zn2+-activated chloride channel. This might be exploited for the design of metal-specific biosensors by modeling-assisted mutagenesis. |
قاعدة البيانات: | Supplemental Index |
تدمد: | 19336950 19336969 |
---|---|
DOI: | 10.4161/chan.2.1.5931 |