The role of the divalent cation in the structure of the I domain from the CD11a/CD18 integrin.
Qu, A., Leahy, D.J.(1996) Structure 4: 931-942
- PubMed: 8805579 
- DOI: https://doi.org/10.1016/s0969-2126(96)00100-1
- Primary Citation of Related Structures:  
1ZON, 1ZOO, 1ZOP - PubMed Abstract: 
The integrin family of cell-surface receptors mediates a wide variety of cell-cell and cell-extracellular matrix interactions. Integrin-ligand interactions are invariably dependent on the presence of divalent cations, and a subset of integrins contain a approximately 200 amino acid inserted (I) domain that is important for ligand binding activity and contains a single divalent cation binding site. Many integrins are believed to respond to stimuli by undergoing a conformational change that increases their affinity for ligand, and there is a clear difference between two crystal structures of the CD11b I domain with different divalent cations (magnesium and manganese) bound. In addition to the different bound cation, a 'ligand mimetic' crystal lattice interaction in the CD11b I domain structure with bound magnesium has led to the interpretation that the different CD11b I domain structures represent different affinity states of I domains. The influence of the bound cation on I domain structure and function remains incompletely understood, however. The crystal structure of the CD11a I domain bound to manganese is known. We therefore set out to determine whether this structure changes when the metal ion is altered or removed.
Organizational Affiliation: 
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.