6XQO | pdb_00006xqo

Structure of the human MICU1-MICU2 heterodimer, calcium bound, in association with a lipid nanodisc

• PDB DOI: https://doi.org/10.2210/pdb6XQO/pdb
• EM Map EMD-22291: EMDB EMDataResource

• Classification: CALCIUM BINDING PROTEIN
• Organism(s): Homo sapiens
• Expression System: Homo sapiens
• Mutation(s): No 


• Deposited: 2020-07-09 Released: 2020-07-29 
• Deposition Author(s): Long, S.B., Wang, C., Baradaran, R., Jacewicz, A., Delgado, B.
• Funding Organization(s): National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS), National Institutes of Health/National Cancer Institute (NIH/NCI)

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.10 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Structures reveal gatekeeping of the mitochondrial Ca 2+ uniporter by MICU1-MICU2.

Wang, C., Jacewicz, A., Delgado, B.D., Baradaran, R., Long, S.B.

(2020) Elife 9

• PubMed: 32667285 
• DOI: https://doi.org/10.7554/eLife.59991
• Primary Citation Related Structures: 
  6XQN, 6XQO


• PubMed Abstract: 
  

  The mitochondrial calcium uniporter is a Ca ²⁺ -gated ion channel complex that controls mitochondrial Ca ²⁺ entry and regulates cell metabolism. MCU and EMRE form the channel while Ca ²⁺ -dependent regulation is conferred by MICU1 and MICU2 through an enigmatic process. We present a cryo-EM structure of an MCU-EMRE-MICU1-MICU2 holocomplex comprising MCU and EMRE subunits from the beetle Tribolium castaneum in complex with a human MICU1-MICU2 heterodimer at 3.3 Å resolution. With analogy to how neuronal channels are blocked by protein toxins, a uniporter interaction domain on MICU1 binds to a channel receptor site comprising MCU and EMRE subunits to inhibit ion flow under resting Ca ²⁺ conditions. A Ca ²⁺ -bound structure of MICU1-MICU2 at 3.1 Å resolution indicates how Ca ²⁺ -dependent changes enable dynamic response to cytosolic Ca ²⁺ signals.

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Organizational Affiliation: 
• Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States.
Graduate Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Medicine Graduate School of Medical Sciences, New York, United States.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 Pseudo Symmetry: Cyclic - C2  (Explore in 3D)
Pseudo Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: gel filtration

Macromolecule Content 

• Total Structure Weight: 90.56 kDa 
• Atom Count: 4,301 
• Modeled Residue Count: 560 
• Deposited Residue Count: 777 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Calcium uptake protein 1, mitochondrial	A [auth I]	394	Homo sapiens	Mutation(s): 0  Gene Names: MICU1, CALC, CBARA1
UniProt & NIH Common Fund Data Resources
Find proteins for Q9BPX6 (Homo sapiens) Explore Q9BPX6  Go to UniProtKB:  Q9BPX6
PHAROS:  Q9BPX6 GTEx:  ENSG00000107745

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Calcium uptake protein 2, mitochondrial	B [auth J]	383	Homo sapiens	Mutation(s): 0  Gene Names: MICU2, EFHA1
UniProt & NIH Common Fund Data Resources
Find proteins for Q8IYU8 (Homo sapiens) Explore Q8IYU8  Go to UniProtKB:  Q8IYU8
PHAROS:  Q8IYU8 GTEx:  ENSG00000165487

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CA	C [auth I], D [auth I], E [auth J], F [auth J]	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.10 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.17.1-3660
RECONSTRUCTION	RELION	3.0

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2020-07-29 
Deposition Author(s): Long, S.B., Wang, C., Baradaran, R., Jacewicz, A., Delgado, B.

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Funding Organization	Location	Grant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)	United States	R35GM131921
National Institutes of Health/National Cancer Institute (NIH/NCI)	United States	P30CA008748

Revision History  

• Version 1.0: 2020-07-29
  Type: Initial release
  
• Version 1.1: 2020-08-05
  Changes: Database references
• Version 1.2: 2020-09-30
  Changes: Database references
• Version 1.3: 2024-03-06
  Changes: Data collection, Database references