Biological Assembly 1  

 3D View: Structure | Electron Density

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 8-mer - A4B4 Pseudo Symmetry: Asymmetric - C1 
Pseudo Stoichiometry: Hetero 8-mer - A4B2C2 

Biological assembly 1 assigned by authors and generated by PQS (software)

Macromolecule Content

• Total Structure Weight: 140.56 kDa 
• Atom Count: 9928 
• Residue Count: 1146 
• Unique protein chains: 2

1GO4

Crystal structure of Mad1-Mad2 reveals a conserved Mad2 binding motif in Mad1 and Cdc20.

• DOI: 10.2210/pdb1GO4/pdb

• Classification: CELL CYCLE
• Organism(s): Homo sapiens
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 2001-10-17 Released: 2002-05-16 
• Deposition Author(s): Sironi, L., Mapelli, M., Jeang, K.T., Musacchio, A.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.05 Å
• R-Value Free: 0.268 
• R-Value Work: 0.240 
• R-Value Observed: 0.240 

Literature

Crystal structure of the tetrameric Mad1-Mad2 core complex: implications of a 'safety belt' binding mechanism for the spindle checkpoint.

Sironi, L., Mapelli, M., Knapp, S., De Antoni, A., Jeang, K.T., Musacchio, A.

(2002) EMBO J 21: 2496-2506

• PubMed: 12006501 
• DOI: 10.1093/emboj/21.10.2496
• Primary Citation of Related Structures:  
  1GO4


• PubMed Abstract: 
  

The spindle checkpoint protein Mad1 recruits Mad2 to unattached kinetochores and is essential for Mad2-Cdc20 complex formation in vivo but not in vitro. The crystal structure of the Mad1-Mad2 complex reveals an asymmetric tetramer, with elongated Mad1 monomers parting from a coiled-coil to form two connected sub-complexes with Mad2. The Mad2 C-terminal tails are hinged mobile elements wrapping around the elongated ligands like molecular 'safety belts'. We show that Mad1 is a competitive inhibitor of the Mad2-Cdc20 complex, and propose that the Mad1-Mad2 complex acts as a regulated gate to control Mad2 release for Cdc20 binding. Mad1-Mad2 is strongly stabilized in the tetramer, but a 1:1 Mad1-Mad2 complex slowly releases Mad2 for Cdc20 binding, driven by favourable binding energies. Thus, the rate of Mad2 binding to Cdc20 during checkpoint activation may be regulated by conformational changes that destabilize the tetrameric Mad1-Mad2 assembly to promote Mad2 release. We also show that unlocking the Mad2 C-terminal tail is required for ligand release from Mad2, and that the 'safety belt' mechanism may prolong the lifetime of Mad2-ligand complexes.

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Organizational Affiliation: 

Structural Biology Unit, Department of Experimental Oncology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Mitotic spindle assembly checkpoint protein MAD2A	A, B, C, D	205	Homo sapiens	Mutation(s): 1  Gene Names: MAD2L1, MAD2
Find proteins for Q13257 (Homo sapiens) Explore Q13257  Go to UniProtKB:  Q13257
NIH Common Fund Data Resources
PHAROS  Q13257 GTEx  ENSG00000164109

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Mitotic spindle assembly checkpoint protein MAD1	E, F, G, H	100	Homo sapiens	Mutation(s): 0  Gene Names: MAD1L1, MAD1, TXBP181
Find proteins for Q9Y6D9 (Homo sapiens) Explore Q9Y6D9  Go to UniProtKB:  Q9Y6D9
NIH Common Fund Data Resources
PHAROS  Q9Y6D9 GTEx  ENSG00000002822

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.05 Å
• R-Value Free: 0.268 
• R-Value Work: 0.240 
• R-Value Observed: 0.240 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 111.037	α = 90
b = 63.023	β = 111.65
c = 139.511	γ = 90

Software Package:

Software Name	Purpose
CNS	refinement
DENZO	data reduction
SCALEPACK	data scaling
SnB	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2001-10-17 
• Released Date: 2002-05-16 
Deposition Author(s): Sironi, L., Mapelli, M., Jeang, K.T., Musacchio, A.

Revision History 

• Version 1.0: 2002-05-16
  Type: Initial release
  
• Version 1.1: 2011-05-08
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2017-07-05
  Changes: Refinement description
• Version 1.4: 2018-06-20
  Changes: Data collection, Database references, Source and taxonomy, Structure summary
• Version 1.5: 2019-05-08
  Changes: Data collection, Experimental preparation
• Version 1.6: 2019-10-16
  Changes: Data collection