Solution structure of Hbeta4 extracellular loop of BK potassium channel

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

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Solution structure of extracellular loop of human beta 4 subunit of BK channel and its biological implication on ChTX sensitivity.

Wang, Y.Lan, W.Yan, Z.Gao, J.Liu, X.Wang, S.Guo, X.Wang, C.Zhou, H.Ding, J.Cao, C.

(2018) Sci Rep 8: 4571-4571

  • DOI: https://doi.org/10.1038/s41598-018-23016-y
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Large-conductance Ca 2+ - and voltage-dependent K + (BK) channels display diverse biological functions while their pore-forming α subunit is coded by a single Slo1 gene. The variety of BK channels is correlated with the effects of BKα coexpression with auxiliary β (β1-β4) subunits, as well as newly defined γ subunits. Charybdotoxin (ChTX) blocks BK channel through physically occluding the K + -conduction pore. Human brain enriched β4 subunit (hβ4) alters the conductance-voltage curve, slows activation and deactivation time courses of BK channels. Its extracellular loop (hβ4-loop) specifically impedes ChTX to bind BK channel pore. However, the structure of β4 subunit's extracellular loop and the molecular mechanism for gating kinetics, toxin sensitivity of BK channels regulated by β4 are still unclear. To address them, here, we first identified four disulfide bonds in hβ4-loop by mass spectroscopy and NMR techniques. Then we determined its three-dimensional solution structure, performed NMR titration and electrophysiological analysis, and found that residue Asn123 of β4 subunit regulated the gating and pharmacological characteristics of BK channel. Finally, by constructing structure models of BKα/β4 and thermodynamic double-mutant cycle analysis, we proposed that BKα subunit might interact with β4 subunit through the conserved residue Glu264(BKα) coupling with residue Asn123(β4).

  • Organizational Affiliation

    State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS), 345 Lingling Road, Shanghai, 200032, China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Calcium-activated potassium channel subunit beta-4122Homo sapiensMutation(s): 0 
Gene Names: KCNMB4
UniProt & NIH Common Fund Data Resources
Find proteins for Q86W47 (Homo sapiens)
Explore Q86W47 
Go to UniProtKB:  Q86W47
GTEx:  ENSG00000135643 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ86W47
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2018-08-01
    Type: Initial release
  • Version 1.1: 2023-06-14
    Changes: Database references, Other