Biological Assembly 1  

 3D View: Structure | Electron Density

Global Symmetry: Cyclic - C3  (3D View)
Global Stoichiometry: Homo 3-mer - A3 

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

Macromolecule Content

• Total Structure Weight: 88.04 kDa 
• Atom Count: 5431 
• Residue Count: 699 
• Unique protein chains: 1

1G88

S4AFL3ARG515 MUTANT

• DOI: 10.2210/pdb1G88/pdb

• Classification: TRANSCRIPTION
• Organism(s): Homo sapiens
• Mutation(s): Yes 


• Deposited: 2000-11-16 Released: 2000-11-29 
• Deposition Author(s): Chako, B.M., Qin, B., Lam, S.S., Correia, J.J., Lin, K.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 3.00 Å
• R-Value Free: 0.263 
• R-Value Work: 0.203 
• R-Value Observed: 0.203 

Literature

The L3 loop and C-terminal phosphorylation jointly define Smad protein trimerization.

Chacko, B.M., Qin, B., Correia, J.J., Lam, S.S., de Caestecker, M.P., Lin, K.

(2001) Nat Struct Biol 8: 248-253

• PubMed: 11224571 
• DOI: 10.1038/84995
• Structures With Same Primary Citation


• PubMed Abstract: 
  

Smad proteins mediate the transforming growth factor beta responses. C-terminal phosphorylation of R-Smads leads to the recruitment of Smad4 and the formation of active signaling complexes. We investigated the mechanism of phosphorylation-induced Smad complex formation with an activating pseudo-phosphorylated Smad3. Pseudo-phosphorylated Smad3 has a greater propensity to homotrimerize, and recruits Smad4 to form a heterotrimer containing two Smad3 and one Smad4. The trimeric interaction is mediated through conserved interfaces to which tumorigenic mutations map. Furthermore, a conserved Arg residue within the L3 loop, located near the C-terminal phosphorylation sites of the neighboring subunit, is essential for trimerization. We propose that the phosphorylated C-terminal residues interact with the L3 loop of the neighboring subunit to stabilize the trimer interaction.

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Organizational Affiliation: 

Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, Massachusetts 01655, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
SMAD4	A, B, C	268	Homo sapiens	Mutation(s): 1  Gene Names: SMAD4, DPC4, MADH4
Find proteins for Q13485 (Homo sapiens) Go to UniProtKB:  Q13485
NIH Common Fund Data Resources
PHAROS  Q13485 GTEx  ENSG00000141646

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 3.00 Å
• R-Value Free: 0.263 
• R-Value Work: 0.203 
• R-Value Observed: 0.203 
• Space Group: I 4₁ 2 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 140.855	α = 90
b = 140.855	β = 90
c = 194.613	γ = 90

Software Package:

Software Name	Purpose
AMoRE	phasing
CNS	refinement
DENZO	data reduction
CCP4	data scaling

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2000-11-16 
• Released Date: 2000-11-29 
Deposition Author(s): Chako, B.M., Qin, B., Lam, S.S., Correia, J.J., Lin, K.

Revision History 

• Version 1.0: 2000-11-29
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance