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Solution structure of the Mesorhizobium loti K1 channel cyclic nucleotide‐binding domain in complex with cAMP
Author(s) -
Schünke Sven,
Stoldt Matthias,
Novak Kerstin,
Kaupp U Benjamin,
Willbold Dieter
Publication year - 2009
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/embor.2009.68
Subject(s) - cyclic nucleotide binding domain , dimer , cyclic nucleotide gated ion channel , nucleotide , chemistry , biophysics , helix bundle , ion channel , heterotetramer , potassium channel , gating , cyclic nucleotide , stereochemistry , protein structure , crystallography , biochemistry , biology , receptor , protein subunit , organic chemistry , gene
Cyclic nucleotide‐sensitive ion channels, known as HCN and CNG channels, are crucial in neuronal excitability and signal transduction of sensory cells. HCN and CNG channels are activated by binding of cyclic nucleotides to their intracellular cyclic nucleotide‐binding domain (CNBD). However, the mechanism by which the binding of cyclic nucleotides opens these channels is not well understood. Here, we report the solution structure of the isolated CNBD of a cyclic nucleotide‐sensitive K + channel from Mesorhizobium loti . The protein consists of a wide anti‐parallel β‐roll topped by a helical bundle comprising five α‐helices and a short 3 10 ‐helix. In contrast to the dimeric arrangement (‘dimer‐of‐dimers’) in the crystal structure, the solution structure clearly shows a monomeric fold. The monomeric structure of the CNBD supports the hypothesis that the CNBDs transmit the binding signal to the channel pore independently of each other.