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Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques
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Published on: July 5, 2018

The crystal structure of the plexin-semaphorin-integrin domain/hybrid domain/I-EGF1 segment from the human integrin

MinLong Shi1, Kumar Sundramurthy, Bin Liu

  • 1School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.

The Journal of Biological Chemistry
|June 21, 2005
PubMed

Integrins are modular (alphabeta) heterodimeric proteins that mediate cell adhesion and convey signals across the plasma membrane. Interdomain motions play a key role in signal transduction by propagating structural changes through the molecule, thus controlling the activation state and adhesive properties of the integrin. We expressed a soluble fragment of the human integrin beta2 subunit comprising the plexin-semaphorin-integrin domain (PSI)/hybrid domain/I-EGF1 fragment and present its crystal structure at 1.8-A resolution. The structure reveals an elongated molecule with a rigid architecture stabilized by nine disulfide bridges. The PSI domain is located centrally and participates in the formation of extended interfaces with the hybrid domain and I-EGF1 domains, respectively. The hybrid domain/PSI interface involves the burial of an Arg residue, and contacts between PSI and I-EGF1 are mainly mediated by well conserved Arg and Trp residues. Conservation of key interacting residues across the various integrin beta subunits sequences suggests that our structure represents a good model for the entire integrin family. Superposition with the integrin beta3 receptor in its bent conformation suggests that an articulation point is present at the linkage between its I-EGF1 and I-EGF2 modules and underlines the importance of this region for the control of integrin-mediated cell adhesion.

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