Role of the cys loop and transmembrane domain in the allosteric modulation of alpha 4 beta 2 nicotinic acetylcholine receptors
| Autor: | Manuel Faundez, Isabel Bermudez, Teresa Minguez, Philip C. Biggin, Patricio Iturriaga-Vásquez, Constanza Alcaino, Simone Mazzaferro, Maria Musgaard |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Stereochemistry Allosteric regulation Receptors Nicotinic Biochemistry Protein Structure Secondary Xenopus laevis 03 medical and health sciences chemistry.chemical_compound Allosteric Regulation Protein Domains Animals Humans Homology modeling Binding site Molecular Biology Ion channel Acetylcholine receptor Estradiol Chemistry Cell Biology Transmembrane domain 030104 developmental biology Nicotinic agonist Desformylflustrabromine Signal Transduction |
| Zdroj: | Journal Of Biological Chemistry Artículos CONICYT CONICYT Chile instacron:CONICYT |
| Popis: | Allosteric modulators of pentameric ligand-gated ion channels are thought to act on elements of the pathways that couple agonist binding to channel gating. Using α4β2 nicotinic acetylcholine receptors and the α4β2-selective positive modulators 17β-estradiol (βEST) and desformylflustrabromine (dFBr), we have identified pathways that link the binding sites for these modulators to the Cys loop, a region that is critical for channel gating in all pentameric ligand-gated ion channels. Previous studies have shown that the binding site for potentiating βEST is in the C-terminal (post-M4) region of the α4 subunit. Here, using homology modeling in combination with mutagenesis and electrophysiology, we identified the binding site for potentiating dFBr on the top half of a cavity between the third (M3) and fourth transmembrane (M4) α-helices of the α4 subunit. We found that the binding sites for βEST and dFBr communicate with the Cys loop, through interactions between the last residue of post-M4 and Phe170 of the conserved FPF sequence of the Cys loop, and that these interactions affect potentiating efficacy. In addition, interactions between a residue in M3 (Tyr309) and Phe167, a residue adjacent to the Cys loop FPF motif, also affect dFBr potentiating efficacy. Thus, the Cys loop acts as a key control element in the allosteric transduction pathway for potentiating βEST and dFBr. Overall, we propose that positive allosteric modulators that bind the M3-M4 cavity or post-M4 region increase the efficacy of channel gating through interactions with the Cys loop. |
| Databáze: | OpenAIRE |
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