Structural and functional modularity of voltage‐gated potassium channels

FEBS Letters

Montal, Mauricio²  Planells-Cases, Rosa²  Caprini, Marco²  Patten, Craig D.¹ 

[1] Department of Physics, University of California at San Diego, La Jolla, CA 92093, USA;Department of Biology, University of California at San Diego, La Jolla, CA 92093, USA

关键词: Potassium channel;    Structure–activity relationship;    Modularity;    Ion channel kinetics;   

DOI  :  10.1016/S0014-5793(99)01659-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Sequence similarity among known potassium channels indicates the voltage-gated potassium channels consist of two modules: the N-terminal portion of the channel up to and including transmembrane segment S4, called in this paper the ‘sensor’ module, and the C-terminal portion from transmembrane segment S5 onwards, called the ‘pore’ module. We investigated the functional role of these modules by constructing chimeric channels which combine the ‘sensor’ from one native voltage-gated channel, mKv1.1, with the ‘pore’ from another, Shaker H4, and vice versa. Functional studies of the wild type and chimeric channels show that these modules can operate outside their native context. Each channel has a unique conductance–voltage relation. Channels incorporating the mKv1.1 sensor module have similar rates of activation while channels having the Shaker pore module show similar rates of deactivation. This observation suggests the mKv1.1 sensor module limits activation and the Shaker pore module determines deactivation. We propose a model that explains the observed equilibrium and kinetic properties of the chimeric constructs in terms of the characteristics of the native modules and a novel type of intrasubunit cooperativity. The properties ascribed to the modules are the same whether the modules function in their native context or have been assembled into a chimera.

【 授权许可】

Unknown