Molecular determinants of external barium block in Shaker potassium channels

FEBS Letters

Hurst, Raymond S.¹  Toro, Ligia¹  Stefani, Enrico² 

[1] Department of Anesthesiology, University of California at Los Angeles, BH-612 CHS, Box 951778, Los Angeles, CA 90095, USA;Department of Physiology, University of California at Los Angeles, Los Angeles, CA 90095, USA

关键词: Barium;    Potassium;    Gating current;    Unitary current;    Pore;   

DOI  :  10.1016/0014-5793(96)00516-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Mutations in the outer pore region of Shaker K⁺ channels (^T449 and D⁴⁴⁷) can influence external Ba²⁺ block. Substitution of T⁴⁴⁹ by A, V or Y differentially reduced Ba²⁺ block primarily by decreasing the blocking rate. Substitution of D⁴⁴⁷ by N resulted in a non-conducting channel with apparently normal gating currents. External Ba²⁺ can speed the OFF gating current of a different non-conducting mutant, W434F; this effect was markedly attenuated by the D447N substitution. These results suggest that D⁴⁴⁷ contributes to an external Ba²⁺ binding site while T⁴⁴⁹ imposes a barrier to the access of that site.

【 授权许可】

Unknown