1MK2 | pdb_00001mk2

SMAD3 SBD complex

• PDB DOI: https://doi.org/10.2210/pdb1MK2/pdb

• Classification: TRANSCRIPTION
• Organism(s): Homo sapiens
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2002-08-28 Released: 2002-10-16 
• Deposition Author(s): Qin, B.Y., Lam, S.S., Correia, J.J., Lin, K.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.74 Å
• R-Value Free: 
  0.271 (Depositor), 0.266 (DCC) 
• R-Value Work: 
  0.227 (Depositor), 0.227 (DCC) 
• R-Value Observed: 
  0.227 (Depositor) 

Literature

Smad3 allostery links TGF-beta receptor kinase activation to transcriptional control

Qin, B.Y., Lam, S.S., Correia, J.J., Lin, K.

(2002) Genes Dev 16: 1950-1963

• PubMed: 12154125 
• DOI: https://doi.org/10.1101/gad.1002002
• Primary Citation Related Structures: 
  1MJS, 1MK2


• PubMed Abstract: 
  

  Smad3 transduces the signals of TGF-betas, coupling transmembrane receptor kinase activation to transcriptional control. The membrane-associated molecule SARA (Smad Anchor for Receptor Activation) recruits Smad3 for phosphorylation by the receptor kinase. Upon phosphorylation, Smad3 dissociates from SARA and enters the nucleus, in which its transcriptional activity can be repressed by Ski. Here, we show that SARA and Ski recognize specifically the monomeric and trimeric forms of Smad3, respectively. Thus, trimerization of Smad3, induced by phosphorylation, simultaneously activates the TGF-beta signal by driving Smad3 dissociation from SARA and sets up the negative feedback mechanism by Ski. Structural models of the Smad3/SARA/receptor kinase complex and Smad3/Ski complex provide insights into the molecular basis of regulation.

---

Organizational Affiliation: 
• Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Hetero 4-mer - A2B2 

Biological assembly 1 assigned by authors.

Biological Assembly 2  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

Biological assembly 2 generated by PISA,PQS (software)

Macromolecule Content 

• Total Structure Weight: 27.29 kDa 
• Atom Count: 1,848 
• Modeled Residue Count: 235 
• Deposited Residue Count: 244 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
SMAD 3	A	206	Homo sapiens	Mutation(s): 0
UniProt & NIH Common Fund Data Resources
Find proteins for P84022 (Homo sapiens) Explore P84022  Go to UniProtKB:  P84022
PHAROS:  P84022 GTEx:  ENSG00000166949

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Madh-interacting protein	B	38	Homo sapiens	Mutation(s): 0
UniProt & NIH Common Fund Data Resources
Find proteins for O95405 (Homo sapiens) Explore O95405  Go to UniProtKB:  O95405
PHAROS:  O95405 GTEx:  ENSG00000157077

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
ACY	C [auth A], D [auth A], E [auth A], F [auth A]	ACETIC ACID C2 H4 O2 QTBSBXVTEAMEQO-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.74 Å
• R-Value Free:  0.271 (Depositor), 0.266 (DCC) 
• R-Value Work:  0.227 (Depositor), 0.227 (DCC) 
• R-Value Observed: 0.227 (Depositor) 

Space Group: P 2₁ 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 49.995	α = 90
b = 71.716	β = 90
c = 86.886	γ = 90

Software Package:

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

Structure Validation

Entry History 

Deposition Data

• Released Date: 2002-10-16 
Deposition Author(s): Qin, B.Y., Lam, S.S., Correia, J.J., Lin, K.

Revision History  

• Version 1.0: 2002-10-16
  Type: Initial release
  
• Version 1.1: 2008-04-28
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Derived calculations, Version format compliance
• Version 1.3: 2024-02-14
  Changes: Data collection, Database references, Derived calculations