Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 22.00 kDa 
• Atom Count: 1486 
• Modelled Residue Count: 184 
• Deposited Residue Count: 192 
• Unique protein chains: 1

1N9Z

INTEGRIN ALPHA M I DOMAIN MUTANT

• PDB DOI: 10.2210/pdb1N9Z/pdb

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


• Deposited: 2002-11-26 Released: 2003-05-20 
• Deposition Author(s): McCleverty, C.J., Liddington, R.C.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.278 
• R-Value Work: 0.242 
• R-Value Observed: 0.247 

Literature

Engineered allosteric mutants of the integrin alphaMbeta2 I domain: structural and functional studies

McCleverty, C.J., Liddington, R.C.

(2003) Biochem J 372: 121-127

• PubMed: 12611591 
• DOI: 10.1042/BJ20021273
• Primary Citation of Related Structures:  
  1MF7, 1N9Z, 1NA5


• PubMed Abstract: 
  

The alpha-I domain, found in the alpha-subunit of the leucocyte integrins such as alphaMbeta2 and alphaLbeta2, switches between the open and closed tertiary conformations, reflecting the high- and low-affinity ligand-binding states of the integrin that are required for regulated cell adhesion and migration. In the present study we show, by using point mutations and engineered disulphide bonds, that ligand affinity can be reduced or increased allosterically by altering the equilibrium between the closed and open states. We determined equilibrium constants for the binding of two ligands, fibrinogen and intercellular cell-adhesion molecule 1, to the alphaM-I domain by surface plasmon resonance, and determined crystal structures of a low-affinity mutant. Locking the domain in the open conformation increases affinity by a factor of no greater than 10, consistent with a closely balanced equilibrium between the two conformations in the absence of ligand. This behaviour contrasts with that of the unliganded alphaL-I domain, for which the equilibrium lies strongly in favour of the closed conformation. These results suggest significant differences in the way the parent integrins regulate I domain conformation and hence ligand affinity.

---

Organizational Affiliation: 

The Burnham Institute, 10901 North Torrey Pines Rd, La Jolla, CA 92037, U.S.A.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Integrin alpha-M	A	192	Homo sapiens	Mutation(s): 3  Gene Names: ITGAM OR CR3A OR CD11B, ITGAM, CD11B, CR3A
UniProt & NIH Common Fund Data Resources
Find proteins for P11215 (Homo sapiens) Explore P11215  Go to UniProtKB:  P11215
PHAROS:  P11215

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
MG	B [auth A]	MAGNESIUM ION Mg JLVVSXFLKOJNIY-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.278 
• R-Value Work: 0.242 
• R-Value Observed: 0.247 
• Space Group: P 4₃

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 44.22	α = 90
b = 44.22	β = 90
c = 99.91	γ = 90

Software Package:

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

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2002-11-26 
• Released Date: 2003-05-20 
Deposition Author(s): McCleverty, C.J., Liddington, R.C.

Revision History  

• Version 1.0: 2003-05-20
  Type: Initial release
  
• Version 1.1: 2008-04-28
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2021-10-27
  Changes: Database references, Derived calculations