Transfer of ion binding site from ether-a-go-go to Shaker: Mg2+ binds to resting state to modulate channel opening.

ABSTRACT: In ether-à-go-go (eag) K(+) channels, extracellular divalent cations bind to the resting voltage sensor and thereby slow activation. Two eag-specific acidic residues in S2 and S3b coordinate the bound ion. Residues located at analogous positions are approximately 4 A apart in the x-ray structure of a Kv1.2/Kv2.1 chimera crystallized in the absence of a membrane potential. It is unknown whether these residues remain in proximity in Kv1 channels at negative voltages when the voltage sensor domain is in its resting conformation. To address this issue, we mutated Shaker residues I287 and F324, which correspond to the binding site residues in eag, to aspartate and recorded ionic and gating currents in the presence and absence of extracellular Mg(2+). In I287D+F324D, Mg(2+) significantly increas

SUBMITTER: Lin MC 

PROVIDER: S-EPMC2860588 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature