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Guo X, Liu H, Huang Z, Wang Y, Zhang Y, Wang LY, Cao C, Wang S, Ding J. Rectification ratio based determination of disulfide bonds of β2 extracellular loop of BK channel. Channels (Austin) 2018; 13:17-32. [PMID: 30477399 PMCID: PMC6298698 DOI: 10.1080/19336950.2018.1551660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Large-conductance Ca2+-activated K+ (BK) channels are composed of a pore-forming α and a variable number of auxiliary β subunits and play important roles in regulating excitability, action potential waveforms and firing patterns, particularly in neurons and endocrine and cardiovascular cells. The β2 subunits increase the diversity of gating and pharmacological properties. Its extracellular loop contains eight cysteine residues, which can pair to form a high-order structure, underlying the stability of the extracellular loop of β2 subunits and the functional effects on BK channels. However, how these cysteines form disulfide bonds still remains unclear. To address this, based on the fact that the rectification and association of BK α to β2 subunits are highly sensitive to disruption of the disulfide bonds in the extracellular loop of β2, we developed a rectification ratio based assay by combining the site-directed mutagenesis, electrophysiology and enzymatic cleavage. Three disulfide bonds: C1(C84)-C5(C113), C3(C101)-C7(C148) and C6(C142)-C8C(174) are successfully deduced in β2 subunit in complex with a BK α subunit, which are helpful to predict structural model of β2 subunits through computational simulation and to understand the interface between the extracellular domain of the β subunits and the pore-forming α subunit.
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Affiliation(s)
- Xiying Guo
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Haowen Liu
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Zhigang Huang
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Yanting Wang
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China.,b State Key Laboratory of Bio-organic and Natural Product Chemistry , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , Shanghai , China
| | - Yan Zhang
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Lu-Yang Wang
- c Program in Neurosciences and Mental Health, SickKids Research Institute and Department of Physiology , University of Toronto , Toronto , Canada
| | - Chunyang Cao
- b State Key Laboratory of Bio-organic and Natural Product Chemistry , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , Shanghai , China
| | - Sheng Wang
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Jiuping Ding
- a Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
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