1zon
CD11A I-DOMAIN WITHOUT BOUND CATION
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OverviewOverview
BACKGROUND: 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. RESULTS: We, report here the crystal structures of the CD11a I domain determined in the, absence of bound metal ion and with bound magnesium ion. No major, structural rearrangements are observed in the metal-binding site of the, CD11a I domain in the absence or presence of bound manganese ion. The, structures of the CD11a I domain with magnesium or manganese bound are, extremely similar. CONCLUSIONS: The conformation of the CD11a I domain is, not altered by changes in metal ion binding. The cation-dependence of, ligand binding thus indicates that the metal ion is either involved in, direct interaction with ligand or required to promote a favorable, quaternary arrangement of the integrin.
About this StructureAbout this Structure
1ZON is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
The role of the divalent cation in the structure of the I domain from the CD11a/CD18 integrin., Qu A, Leahy DJ, Structure. 1996 Aug 15;4(8):931-42. PMID:8805579
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