Pflügers Archiv

, Volume 440, Issue 5, pp 692–698

The properties of the Kir6.1–6.2 tandem channel co-expressed with SUR2A

  • Yutaka Kono
  • Minoru Horie
  • Makoto Takano
  • Hideo Otani
  • Lai-Hua Xie
  • M. Akao
  • Keiko Tsuji
  • Shigetake Sasayama
Original Article

DOI: 10.1007/s004240000315

Cite this article as:
Kono, Y., Horie, M., Takano, M. et al. Pflügers Arch - Eur J Physiol (2000) 440: 692. doi:10.1007/s004240000315

Abstract

Functional ATP-sensitive K (KATP) channels have an octameric subunit structure with four pore-forming subunits (Kir6.x) and four sulfonylurea receptors (SURx). In the present study, the properties of the heteromeric KATP channel whose pore subunits are composed of Kir6.1 and Kir6.2 were examined using a heterologous expression system. In COS7 cells co-transfected with Kir6.1, Kir6.2 and SUR2A at a ratio of 1:1:2, KATP channels showed various unitary conductances between those of Kir6.1/SUR2A (33.6±4.2 pS) and Kir6.2/SUR2A (67.1±1.6 pS). Kir6.1–6.2 tandem protein, constructed by fusing the C-terminus of Kir6.1 to the N-terminus of Kir6.2 with a ten glutamine linker sequence, also formed a channel with an intermediate conductance (58.9±1.5 pS). Kir6.2 and Kir6.1–6.2 showed similar sensitivity to ATP4–: half-maximal inhibition (IC50) was obtained at 14.1±12.8 µM and 17.6±9.6 µM, respectively. In the presence of Mg2+, Kir6.1–6.2 was significantly less sensitive than Kir6.2 to MgATP (IC50=95.5±49.6 µM versus 18.9±5.0 µM). These results suggest that Kir6.1 and Kir6.2 are endowed with the potential to form a heteromeric KATP channel, which has a low sensitivity to MgATP.

ATP-sensitive potassium channel Conformation Kir6.1 Kir6.2 Subunit 

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • Yutaka Kono
    • 1
  • Minoru Horie
    • 1
  • Makoto Takano
    • 2
  • Hideo Otani
    • 1
  • Lai-Hua Xie
    • 2
  • M. Akao
    • 1
  • Keiko Tsuji
    • 1
  • Shigetake Sasayama
    • 1
  1. 1.Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine 54 Kawahara-cho, Sakyou-ku, Kyoto, 606–8507Japan
  2. 2.Department of Physiology and Biophysics, Kyoto University Graduate School of Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Sakyou-ku, Kyoto, 606–8507Japan

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