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Cloning of a cardiac inward rectifier k^+ channel and its gating mechanisms

Research Project

Project/Area Number 06670096
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field General pharmacology
Research InstitutionTohoku University

Principal Investigator

ISHII Kuniaki  Tohoku University, School of Medicine, lecturer, 医学部, 講師 (10184459)

Co-Investigator(Kenkyū-buntansha) NUNOKI Kazuo  Tohoku University, School of Medicine, lecturer, 医学部, 講師 (10172743)
Project Period (FY) 1994 – 1995
Project Status Completed (Fiscal Year 1995)
Budget Amount *help
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywordscloned k channel / inward rectification / heart / patch clamp / Single channel current
Research Abstract

We have isolated a cDNA coding for an inward rectifier K^+ channel (RBHIK1) from rabbit heart. The cloned cDNA encodes a protein of 427 amino acids with two putative transmembrane segments. The primary structure of RBHIK1 is highly homologous to that of IRK1 which is an inward rectifier K^+ channel cloned from mouse macrophage by expression cloning. Howere, there are some amino acid sequence differences observed between RBHIK1 and IRK1 in the segment between the first transmembrane segment and putative pore forming region, which may give rise to some functional differences between RBHIK1 and IRK1. RNA blot analysis revealed the expression of RBHIK1 mRNA (approximate estimated size of 5.5 kb) in various rabbit tissues. There are remarkable differences of the expression of RBHIK1 mRNA between the atrium and ventricle. The highest expression of the mRNA was detected in the ventricle, but no expression was detected in the atrium. The expression pattern is in good agreement with electrophys … More iological findings about the different sizes of native inward rectifier K^+ current in the ventricle and atrium.
2. THe RBHIK1 current showed strong inward rectification. The amplitude of RBHIK1 current, like native inward rectifier K^+ current, increased as extracellular K^+ concentration increased and the current was blocked by Ba^<2+> or Cs^+ in a voltage- and time-dependent manner. However, although RBHIK1 was cloned from rabbit heart, unlike native cardiac inward rectifier, it exhibited no substantial outward current and negative slope conductance when expressed in Xenopus cocyte. In patch clamp experiments with 145 mMK^+ in pipette at 20-22゚C,the single channel conductance of the RBHIK1 channel was 17.8(]SY.+-.])0.47 pS,and that of the native inward rectifier K^+ channel was 23.5(]SY.+-.])0.29 pS.The currents of subconductance state of 2/3 of the full conductance frequently occurred in recordings of the single RBHIK1 channel. The RBHIK1 channel may be composed of three tetrameric constructs. Less

Report

(3 results)
  • 1995 Annual Research Report   Final Research Report Summary
  • 1994 Annual Research Report
  • Research Products

    (17 results)

All Other

All Publications (17 results)

  • [Publications] M. Nagashima et al.: "Unitary curkent through the inwarol rectifier potassium channel cloned from rabbit heart-Comparison with the native potassium channel-" J. Mol. Cell. Cardiol.(in press). (1996)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y. Sasaki et al.: "Voltage-dependent K^+ channel (Kv1.5) cloned from rabbit heart and facilitation of inactivation of the delayed rectifier current by rat β subunit" FEBS. Lett.372. 20-24 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] H. Murakoshi et al.: "Determination of K_A values by controlled receptor expression in Xenopus oocytes" Br. J. Pharmacol.116. 2062-2066 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] T. Yamagishi et al.: "Antiarrhythmic and bradycardic drugs inhibit currents of cloned K^+ channels, Kv1.2 and Kv1.4" Eur. J. Pharmacol.281. 151-159 (1995)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K. Ishii et al.: "Cloning and functional expression of a cardiac inward rectifier K^+ channal" FEBS. Lett.338. 107-111 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] M.Nagashima et al.: "Unitary current through the inward rectifier potassium channel cloned from rabbit heart -Comparison with the native potassium chennel-" J.Mol. Cell. Cardial. (in press).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] Y.Sasaki et al.: "Voltage-dependent K^+ channel (Kv1.5) cloned from rabbit heart and facilitation of inactivation of the delayd rectifier current by rat beta subunit" FEBS Lett.vol.372. 20-24 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] H.Murakoshi et al.: "Determination of KA values by controlled receptor expression in Xenopus oocytes" Br. J.Pharnacol.vol.116. 2062-2066 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] T.Yamagishi et al.: "Antiarrhythmic and bradycardic drugs inhibit currents of cloned K^+ channels, Kv1.2 and Kv1.4" Eur. J.Pharmacol. vol.281. 151-159 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] K.Ishii et al.: "Cloning and functional expkession of a cardiac inward rectifier K^+ channel" FEBS Lett.vol.338. 107-111 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1995 Final Research Report Summary
  • [Publications] M. Nagashima et al.: "Unitary current through the inward rectifier potassium channel clomed from rabbit heart-Comparison with the native potassium channel-" J. Mol. Cell. Cardiol.(in press). (1996)

    • Related Report
      1995 Annual Research Report
  • [Publications] Y. Sasaki et al.: "Voltage-dependent K^+ channel (Kvi.5) cloned from rabbit heart and facilitation of inactivation of the delayed rectifier current by rat β subunit" FEBS Lett.372. 20-24 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] H. Murakoshi et al.: "Determination of K_A Values by controlled receptor expression in Xenopus oocytes" Br. J. Pharmacol.116. 2062-2066 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] T. Yamagishi et al.: "Antiarrhymic and brodycardic drugs inhibit currents of cloned K^+ channels, Kv1.2 and Kv1.4" Eur. J. Pharmacol.281. 151-159 (1995)

    • Related Report
      1995 Annual Research Report
  • [Publications] K.Ishii et.al.: "The amino acid residues responsible for sensitivity to pH of cloned K^+ channel" Heart and Vessels. (in press).

    • Related Report
      1994 Annual Research Report
  • [Publications] K.Nunoki et.al.: "Hybrid potassium chnnel by tandem linkage of inactivating and non-inactivating Subunits" J.Biol.Chem. 269. 24138-24142 (1994)

    • Related Report
      1994 Annual Research Report
  • [Publications] K.Ishii et.al.: "Cloning and functional expression of a cardiac in ward rectifier K^+ channel" FEBS Lett. 338. 107-111 (1994)

    • Related Report
      1994 Annual Research Report

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Published: 1994-04-01   Modified: 2016-04-21  

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