Extracellular proton alters the divalent cation binding affinity in a cyclic nucleotide‐gated channel pore

FEBS Letters

Park, Chul-Seung¹  Rho, Seong-Hwan¹ 

[1] Department of Life Science, Kwangju Institute of Science and Technology (K-JIST), 572 Sangam-dong, Kwangsan-Ku, Kwangju 506-712, South Korea

关键词: Extracellular proton;    Cyclic nucleotide-gated channel;    Binding affinity;    Glutamate residue;    CNG;    cyclic nucleotide-gated;    cGMP;    guanosine 3′;    5′-cyclic mononucleotide;    P-region;    pore-forming region;    Asp;    aspartate;    Glu;    glutamate;    Gly;    glycine;   

DOI  :  10.1016/S0014-5793(98)01353-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Extracellular protons in the range of 10⁻⁹ to 10⁻⁵ M effectively suppressed Na⁺ current (K _1/2=10^−6.1) through the bovine retinal guanosine 3′,5′-cyclic mononucleotide-gated ion channel expressed in Xenopus oocytes. The reduction of channel current was mediated by a single glutamate residue (Glu363) within the pore-forming region of the channel, also involved in extracellular divalent cation binding. Increasing the concentration of extracellular proton decreased the binding affinity of the extracellular divalent cation (e.g. Sr²⁺) and the large difference of binding affinity previously observed between the wild-type and E363D mutant channel disappeared. These results indicate that the permeation characteristics of cyclic nucleotide-gated ion channel can be altered by extracellular pH through a single acidic residue in the channel conduction pathway.

【 授权许可】

Unknown