Title

A Novel Fluorescent α-Conotoxin For The Study Of α7 Nicotinic Acetylcholine Receptors

Department

neurobiology

Document Type

Article

Abstract

Homomeric α7 nicotinic acetylcholine receptors are a well-established, pharmacologically distinct subtype. The more recently identified α9 subunit can also form functional homopentamers as well as α9α10 heteropentamers. Current fluorescent probes for α7 nicotinic ACh receptors are derived from α-bungarotoxin (α-BgTx). However, α-BgTx also binds to α9* and α1* receptors which are coexpressed with α7 in multiple tissues. We used an analog of α-conotoxin ArIB to develop a highly selective fluorescent probe for α7 receptors. This fluorescent α-conotoxin, Cy3-ArIB[V11L;V16A], blocked ACh-evoked α7 currents in Xenopus laevis oocytes with an IC50 value of 2.0 nM. Observed rates of blockade were minute-scale with recovery from blockade even slower. Unlike FITC-conjugated α-BgTx, Cy3-ArIB[V11L;V16A] did not block α9α10 or α1β1Δε receptors. In competition binding assays, Cy3-ArIB[V11L;V16A] potently displaced [125I]-α-BgTx binding to mouse hippocampal membranes with a Ki value of 21 nM. Application of Cy3-ArIB[V11L;V16A] resulted in specific punctate labeling of KXα7R1 cells but not KXα3β2R4, KXα3β4R2, or KXα4β2R2 cells. This labeling could be abolished by pre-treatment with α-cobratoxin. Thus, Cy3-ArIB[V11L;V16A] is a novel and selective fluorescent probe for α7 receptors. © 2009 International Society for Neurochemistry.

Publication Date

10-1-2009

Publication Title

Journal of Neurochemistry

ISSN

00223042

Volume

111

Issue

1

First Page

80

Last Page

89

Digital Object Identifier (DOI)

10.1111/j.1471-4159.2009.06299.x

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