Crystal Structure Analysis of a Eukaryotic Membrane Protein

Experimental Data Snapshot

  • Resolution: 3.70 Å
  • R-Value Free: 0.327 
  • R-Value Work: 0.311 
  • R-Value Observed: 0.312 

Starting Model: experimental
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Structural basis for activity of TRIC counter-ion channels in calcium release.

Wang, X.H.Su, M.Gao, F.Xie, W.Zeng, Y.Li, D.L.Liu, X.L.Zhao, H.Qin, L.Li, F.Liu, Q.Clarke, O.B.Lam, S.M.Shui, G.H.Hendrickson, W.A.Chen, Y.H.

(2019) Proc Natl Acad Sci U S A 116: 4238-4243

  • DOI: https://doi.org/10.1073/pnas.1817271116
  • Primary Citation of Related Structures:  
    6IYU, 6IYX, 6IYZ, 6IZ0, 6IZ1, 6IZ3, 6IZ4, 6IZ5, 6IZ6, 6IZF

  • PubMed Abstract: 

    Trimeric intracellular cation (TRIC) channels are thought to provide counter-ion currents that facilitate the active release of Ca 2+ from intracellular stores. TRIC activity is controlled by voltage and Ca 2+ modulation, but underlying mechanisms have remained unknown. Here we describe high-resolution crystal structures of vertebrate TRIC-A and TRIC-B channels, both in Ca 2+ -bound and Ca 2+ -free states, and we analyze conductance properties in structure-inspired mutagenesis experiments. The TRIC channels are symmetric trimers, wherein we find a pore in each protomer that is gated by a highly conserved lysine residue. In the resting state, Ca 2+ binding at the luminal surface of TRIC-A, on its threefold axis, stabilizes lysine blockage of the pores. During active Ca 2+ release, luminal Ca 2+ depletion removes inhibition to permit the lysine-bearing and voltage-sensing helix to move in response to consequent membrane hyperpolarization. Diacylglycerol is found at interprotomer interfaces, suggesting a role in metabolic control.

  • Organizational Affiliation

    State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Trimeric intracellular cation channel type B-B314Xenopus laevisMutation(s): 0 
Gene Names: tmem38b-b
Membrane Entity: Yes 
Find proteins for Q6GN30 (Xenopus laevis)
Explore Q6GN30 
Go to UniProtKB:  Q6GN30
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ6GN30
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.70 Å
  • R-Value Free: 0.327 
  • R-Value Work: 0.311 
  • R-Value Observed: 0.312 
  • Space Group: F 4 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 250.009α = 90
b = 250.009β = 90
c = 250.009γ = 90
Software Package:
Software NamePurpose
Aimlessdata scaling
PDB_EXTRACTdata extraction
XDSdata reduction

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Ministry of Science and Technology (China)China2016YFA0500503
Ministry of Science and Technology (China)China2015CB910102

Revision History  (Full details and data files)

  • Version 1.0: 2019-05-01
    Type: Initial release
  • Version 1.1: 2019-11-06
    Changes: Data collection, Database references
  • Version 1.2: 2023-11-22
    Changes: Data collection, Database references, Refinement description