A negatively charged region of the N-terminal portion of the skeletal ryanodine receptor (RyR), located between residues 1872–1923, is involved in Ca 2+-dependent regulation of the Ca2+-release channel. This region is divergent between the skeletal (RyR1) and cardiac (RyR2) isoforms of the channel, and is known as D3. Ca2+ exerts important regulatory functions on the RyR, being involved in both activation and inactivation functions of the channel, i.e. the effects occurring at micromolar and millimolar Ca2+ concentrations respectively. To characterize the role of D3 in the Ca2+-dependent regulation of the Ca2+-release channel, we studied the functional consequences of deleting the D3 region from RyR1 (∆D3-RyR1) using a heterologous expression system, [3H]ryanodine binding assays and single-channel recordings in lipid bilayers. Deletion of the D3 region selectively affected Ca2+-dependent regulation of RyR1, but did not alter [3H]ryanodine binding or the effect of other modulators on the RyR. Compared with full-length RyR1 (wt-RyR1), the Ca2+-dependence curve of ∆D3-RyR1 is broader, reflecting increased sensitivity to Ca2+ activation and decreased sensitivity to Ca2+ inactivation. In addition, ∆D3-RyR1 was more resistant to inhibition by Mg2+. Comparison of the effect of caffeine on wt-RyR1 and ∆D3-RyR1 suggested that D3 is an important region of RyR that participates in Ca2+-dependent activation and inactivation of the Ca2+-release channel.
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Research Article|
September 26 2000
Characterization of a calcium-regulation domain of the skeletal-muscle ryanodine receptor
Salim M. HAYEK;
Salim M. HAYEK
1
*Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH 44106, U.S.A.
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Xinsheng ZHU;
Xinsheng ZHU
1
†Department of Physiology, University of Wisconsin Medical School, 1300 University Ave, Madison, WI 53706, U.S.A.
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Manjunatha B. BHAT;
Manjunatha B. BHAT
*Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH 44106, U.S.A.
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Jiying ZHAO;
Jiying ZHAO
*Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH 44106, U.S.A.
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Hiroshi TAKESHIMA;
Hiroshi TAKESHIMA
‡Division of Cell Biology, Kurume University, 2432-3 Aikawa, Kurume, Fukuoka 839-0861, Japan
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Hector H. VALDIVIA;
Hector H. VALDIVIA
2
†Department of Physiology, University of Wisconsin Medical School, 1300 University Ave, Madison, WI 53706, U.S.A.
2To whom correspondence should be addressed (e-mail valdivia@physiology.wisc.edu)
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Jianjie MA
Jianjie MA
*Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Ave, Cleveland, OH 44106, U.S.A.
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Publisher: Portland Press Ltd
Received:
April 07 2000
Revision Received:
June 27 2000
Accepted:
July 17 2000
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 2000
2000
Biochem J (2000) 351 (1): 57–65.
Article history
Received:
April 07 2000
Revision Received:
June 27 2000
Accepted:
July 17 2000
Citation
Salim M. HAYEK, Xinsheng ZHU, Manjunatha B. BHAT, Jiying ZHAO, Hiroshi TAKESHIMA, Hector H. VALDIVIA, Jianjie MA; Characterization of a calcium-regulation domain of the skeletal-muscle ryanodine receptor. Biochem J 1 October 2000; 351 (1): 57–65. doi: https://doi.org/10.1042/bj3510057
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