Title : Crystal structure of the extracellular segment of integrin alpha Vbeta3
Abstract :
- Integrins are alphabeta heterodimeric receptors that mediate divalent cation-dependent cell-cell and cell-matrix adhesion through tightly regulated interactions with ligands
- We have solved the crystal structure of the extracellular portion of integrin alphaVbeta3 at 3 .1 A resolution
- Its 12 domains assemble into an ovoid "head" and two "tails.
- In the crystal, alphaVbeta3 is severely bent at a defined region in its tails , reflecting an unusual flexibility that may be linked to integrin regulation
- The main inter-subunit interface lies within the head, between a seven-bladed beta-propeller from alphaV and an A domain from beta3, and bears a striking resemblance to the Galpha/Gbeta interface in G proteins
- A metal ion-dependent adhesion site ( MIDAS ) in the betaA domain is position ed to participate in a ligand-binding interface formed of loops from the propeller and betaA domains
- MIDAS lies adjacent to a calcium-binding site with a potential regulatory function