Biological Assembly 1  

 3D View: Structure | 1D-3D View | Validation Report

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

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

Macromolecule Content

• Total Structure Weight: 25.54 kDa 
• Atom Count: 1757 
• Modelled Residue Count: 203 
• Deposited Residue Count: 227 
• Unique protein chains: 1

1KHX

Crystal structure of a phosphorylated Smad2

• PDB DOI: 10.2210/pdb1KHX/pdb

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


• Deposited: 2001-12-01 Released: 2002-02-06 
• Deposition Author(s): Wu, J.-W., Hu, M., Chai, J., Seoane, J., Huse, M., Kyin, S., Muir, T.W., Fairman, R., Massague, J., Shi, Y.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.80 Å
• R-Value Free: 0.241 
• R-Value Work: 0.215 
• R-Value Observed: 0.220 

Literature

Crystal structure of a phosphorylated Smad2. Recognition of phosphoserine by the MH2 domain and insights on Smad function in TGF-beta signaling.

Wu, J.W., Hu, M., Chai, J., Seoane, J., Huse, M., Li, C., Rigotti, D.J., Kyin, S., Muir, T.W., Fairman, R., Massague, J., Shi, Y.

(2001) Mol Cell 8: 1277-1289

• PubMed: 11779503 
• DOI: 10.1016/s1097-2765(01)00421-x
• Primary Citation of Related Structures:  
  1KHX


• PubMed Abstract: 
  

Ligand-induced phosphorylation of the receptor-regulated Smads (R-Smads) is essential in the receptor Ser/Thr kinase-mediated TGF-beta signaling. The crystal structure of a phosphorylated Smad2, at 1.8 A resolution, reveals the formation of a homotrimer mediated by the C-terminal phosphoserine (pSer) residues. The pSer binding surface on the MH2 domain, frequently targeted for inactivation in cancers, is highly conserved among the Co- and R-Smads. This finding, together with mutagenesis data, pinpoints a functional interface between Smad2 and Smad4. In addition, the pSer binding surface on the MH2 domain coincides with the surface on R-Smads that is required for docking interactions with the serine-phosphorylated receptor kinases. These observations define a bifunctional role for the MH2 domain as a pSer-X-pSer binding module in receptor Ser/Thr kinase signaling pathways.

---

Organizational Affiliation: 

Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Smad2	A	227	Homo sapiens	Mutation(s): 2  Gene Names: SMAD2, MADH2, MADR2
UniProt & NIH Common Fund Data Resources
Find proteins for Q15796 (Homo sapiens) Explore Q15796  Go to UniProtKB:  Q15796
PHAROS:  Q15796

Small Molecules

Modified Residues  1 Unique
ID	Chains	Type	Formula	2D Diagram	Parent
SEP	A	L-PEPTIDE LINKING	C3 H8 N O6 P		SER

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.80 Å
• R-Value Free: 0.241 
• R-Value Work: 0.215 
• R-Value Observed: 0.220 
• Space Group: I 2₁ 3

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 113.7	α = 90
b = 113.7	β = 90
c = 113.7	γ = 90

Software Package:

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

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2001-12-01 
• Released Date: 2002-02-06 
Deposition Author(s): Wu, J.-W., Hu, M., Chai, J., Seoane, J., Huse, M., Kyin, S., Muir, T.W., Fairman, R., Massague, J., Shi, Y.

Revision History  

• Version 1.0: 2002-02-06
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Derived calculations, Version format compliance