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CELLULAR AND MOLECULAR

Zinc Activates TREK-2 Potassium Channel Activity

Department of Life Science (J.-S.K., J.-Y.P., H.-W.K., E.-J.L., J.-H.L.) and Interdisciplinary Program of Integrated Biotechnology (J.-H.L.), Sogang University, Seoul, Korea; and Department of Physiology (H.B.), Chung-Ang University, Seoul, Korea

TWIK-related K⁺ channel (TREK)-2 is thought to contribute to setting the resting membrane potential and to tuning action potential properties. In the present study, the effects of divalent metal ions (Ba²⁺, Co²⁺, Ni²⁺, Pb²⁺, and Zn²⁺) were examined on TREK-2 expressed in Xenopus oocytes using the two-electrode voltage clamping technique. Pb²⁺ inhibited TREK channel activity (IC₅₀ = 15.6 µM), whereas Zn²⁺ enhanced it in a dose-dependent manner (EC₅₀ = 87.1 µM). Ba²⁺ slightly inhibited TREK currents but only at high concentrations. Co²⁺ and Ni²⁺ had no significant effect. The structural element(s) contributing to the zinc enhancement effect were studied using a series of chimeras consisting of Zn²⁺-activated TREK-2 and Zn²⁺-inhibited TWIK-related acid-sensing K⁺ channel-3. The structural elements were localized to the first pore and the preceding extracellular loop of TREK-2, in which multiple residues, including His121, His156, Asp158, and Asn177, are likely to be involved in the zinc activation effect. Stimulation by Zn²⁺ may be used as a criterion of TREK-2, distinguishing it from other two-pore K⁺ channels.

Address correspondence to: Dr. Jung-Ha Lee, Department of Life Science, Sogang University, Mapo-Gu, Sinsu-Dong 1, Seoul 121-742, Korea. E-mail: jhleem{at}ccs.sogang.ac.kr

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