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1ig5
From Proteopedia
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BOVINE CALBINDIN D9K BINDING MG2+
Overview
The three-dimensional structures of the magnesium- and manganese-bound forms of calbindin D9k were determined to 1.6 A and 1.9 A resolution, respectively, using X-ray crystallography. These two structures are nearly identical but deviate significantly from both the calcium bound form and the metal ion-free (apo) form. The largest structural differences are seen in the C-terminal EF-hand, and involve changes in both metal ion coordination and helix packing. The N-terminal calcium binding site is not occupied by any metal ion in the magnesium and manganese structures, and shows little structural deviation from the apo and calcium bound forms. 1H-NMR and UV spectroscopic studies at physiological ion concentrations show that the C-terminal site of the protein is significantly populated by magnesium at resting cell calcium levels, and that there is a negative allosteric interaction between magnesium and calcium binding. Calcium binding was found to occur with positive cooperativity at physiological magnesium concentration.
About this Structure
1IG5 is a Single protein structure of sequence from Bos taurus with as ligand. This structure supersedes the now removed PDB entry 5ICB. Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Structural basis for the negative allostery between Ca(2+)- and Mg(2+)-binding in the intracellular Ca(2+)-receptor calbindin D9k., Andersson M, Malmendal A, Linse S, Ivarsson I, Forsen S, Svensson LA, Protein Sci. 1997 Jun;6(6):1139-47. PMID:9194174
Page seeded by OCA on Thu Feb 21 13:11:33 2008
