1ig5
From Proteopedia
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. This structure supersedes the now removed PDB entry 5icb. 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 Fri May 2 19:57:50 2008
