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XB-ART-55150
ACS Chem Biol 2018 Sep 21;139:2568-2576. doi: 10.1021/acschembio.8b00513.
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α1-FANGs: Protein Ligands Selective for the α-Bungarotoxin Site of the α1-Nicotinic Acetylcholine Receptor.

Nichols AL , Noridomi K , Hughes CR , Jalali-Yazdi F , Eaton JB , Lai LH , Advani G , Lukas RJ , Lester HA , Chen L , Roberts RW .


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Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that play a central role in neuronal and neuromuscular signal transduction. Here, we have developed FANG ligands, fibronectin antibody-mimetic nicotinic acetylcholine receptor-generated ligands, using mRNA display. We generated a 1 trillion-member primary e10FnIII library to target a stabilized α1 nicotinic subunit (α211). This library yielded 270000 independent potential protein binding ligands. The lead sequence, α1-FANG1, represented 25% of all library sequences, showed the highest-affinity binding, and competed with α-bungarotoxin (α-Btx). To improve this clone, a new library based on α1-FANG1 was subjected to heat, protease, binding, off-rate selective pressures, and point mutations. This resulted in α1-FANG2 and α1-FANG3. These proteins bind α211 with KD values of 3.5 nM and 670 pM, respectively, compete with α-Btx, and show improved subunit specificity. α1-FANG3 is thermostable ( Tm = 62 °C) with a 6 kcal/mol improvement in folding free energy compared with that of the parent α1-FANG1. α1-FANG3 competes directly with the α-Btx binding site of intact neuromuscular heteropentamers [(α1)2β1γδ] in mammalian culture-derived cellular membranes and in Xenopus laevis oocytes expressing these nAChRs. This work demonstrates that mRNA display against a monomeric ecto-domain of a pentamer has the capability to select ligands that bind that subunit in both a monomeric and a pentameric context. Overall, our work provides a route to creating a new family of stable, well-behaved proteins that specifically target this important receptor family.

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Species referenced: Xenopus laevis
Genes referenced: fn1

References [+] :
Arias, Localization of agonist and competitive antagonist binding sites on nicotinic acetylcholine receptors. 2000, Pubmed