Biological Assembly 1  

 3D View: Structure | Ligand Interaction

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Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 22301.39 
• Atom Count: 1491 
• Residue Count: 195 
• Unique protein chains: 1

1M1U

AN ISOLEUCINE-BASED ALLOSTERIC SWITCH CONTROLS AFFINITY AND SHAPE SHIFTING IN INTEGRIN CD11B A-DOMAIN

• DOI: 10.2210/pdb1M1U/pdb

• Classification: CELL ADHESION
• Organism(s): Homo sapiens
• Expression System: Escherichia coli
• Mutation(s): 1 


• Deposited: 2002-06-20 Released: 2002-08-07 
• Deposition Author(s): Xiong, J.-P., Li, R., Essafi, M., Stehle, T., Arnaout, M.A.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.3 Å
• R-Value Free: 0.248 
• R-Value Work: 0.188 

Literature

An isoleucine-based allosteric switch controls affinity and shape shifting in integrin CD11b A-domain.

Xiong, J.P., Li, R., Essafi, M., Stehle, T., Arnaout, M.A.

(2000) J.Biol.Chem. 275: 38762-38767

• PubMed: 11034990 
• DOI: 10.1074/jbc.C000563200


• PubMed Abstract: 
  

In response to cell activation signals, integrins switch from a low to a high affinity state. Physiologic ligands bind to integrins through a von Willebrand Factor A-type domain. Crystallographic studies revealed two conformations of this domain, "closed" and "open." The latter crystallizes in complex with a pseudoligand or ligand, suggesting that it represents the high affinity state; data linking structure and activity are lacking however. In this communication, we expressed stable low and high affinity forms of integrin CD11b A-domain and determined their binding isotherms and crystal structures. The low affinity form, generated by deleting an N-terminal extension extrinsic to the domain, did not bind to physiologic ligands, and crystallized in the closed conformation. The high affinity form was generated by either deleting or substituting an invariable C-terminal Ile(316), wedged into a hydrophobic socket in the closed form, but displaced from it in the open structure. Both mutants crystallized in the open conformation, and the Ile(316) --> Gly-modified integrin displayed high affinity. Structural differences between the low and high affinity forms were detected in solution. These data establish the structure-function correlates for the CD11b A-domain, and define a ligand-independent isoleucine-based allosteric switch intrinsic to this domain that controls its conformation and affinity.

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Organizational Affiliation: 

Leukocyte Biology and Inflammation Program, Renal Unit, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, USA.

Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
Integrin alpha-M	A	195	Homo sapiens	Mutation(s): 1  Gene Names: ITGAM (CD11B, CR3A)
Find proteins for P11215 (Homo sapiens) Go to Gene View: ITGAM Go to UniProtKB:  P11215

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram & Interactions
CA	A	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.3 Å
• R-Value Free: 0.248 
• R-Value Work: 0.188 
• Space Group: P 4₃

Unit Cell:

Length (Å)	Angle (°)
a = 45.700	α = 90.00
b = 45.700	β = 90.00
c = 94.800	γ = 90.00

Software Package:

Software Name	Purpose
SCALEPACK	data scaling
X-PLOR	model building
X-PLOR	refinement
DENZO	data reduction
X-PLOR	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2002-06-20 
• Released Date: 2002-08-07 
• Deposition Author(s): Xiong, J.-P., Li, R., Essafi, M., Stehle, T., Arnaout, M.A.

Revision History 

• Version 1.0: 2002-08-07
  Type: Initial release
• Version 1.1: 2008-04-28
  Type: Version format compliance
• Version 1.2: 2011-07-13
  Type: Version format compliance