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XB-ART-38954
Eur Biophys J 2008 Jul 01;376:947-59. doi: 10.1007/s00249-008-0312-1.
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A comparison of electrophysiological properties of the CNGA1, CNGA1tandem and CNGA1cys-free channels.

Mazzolini M , Nair AV , Torre V .


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Three constructs are used for the analysis of biophysical properties of CNGA1 channels: the WT CNGA1 channel, a CNGA1 channel where all endogenous cysteines were removed (CNGA1cys-free) and a construct composed of two CNGA1 subunits connected by a small linker (CNGA1tandem). So far, it has been assumed, but not proven, that the molecular structure of these ionic channels is almost identical. The I/V relations, ionic selectivity to alkali monovalent cations, blockage by tetracaine and TMA+ were not significantly different. The cGMP dose response and blockage by TEA+ and Cd2+ were instead significantly different in CNGA1 and CNGA1cys-free channels, but not in CNGA1 and CNGA1tandem channels. Cd2+ blocked irreversibly the mutant channel A406C in the absence of cGMP. By contrast, Cd2+ did not block the mutant channel A406C in the CNGA1cys-free background (A406Ccys-free), but an irreversible and almost complete blockage was observed in the presence of the cross-linker M-4-M. Results obtained with different MTS cross-linkers and reagents suggest that the 3D structure of the CNGA1cys-free differs from that of the CNGA1 channel and that the distance between homologous residues at position 406 in CNGA1cys-free is longer than in the WT CNGA1 by several Angstroms.

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Species referenced: Xenopus laevis
Genes referenced: cnga1

References [+] :
Akabas, Acetylcholine receptor channel structure probed in cysteine-substitution mutants. 1992, Pubmed, Xenbase