1IG5

BOVINE CALBINDIN D9K BINDING MG2+

Replaces:  5ICB

Summary for 1IG5

• Entry DOI: 10.2210/pdb1ig5/pdb
• Related: 1IGV 1clb 3icb 4icb
• Descriptor: VITAMIN D-DEPENDENT CALCIUM-BINDING PROTEIN, INTESTINAL, MAGNESIUM ION (3 entities in total)
• Functional Keywords: calcium-binding protein, ef-hand, magnesium binding, metal binding protein
• Biological source: Bos taurus (cattle)
• Total number of polymer chains: 1
• Total formula weight: 8534.86

Authors

Andersson, E.M.,Svensson, L.A. (deposition date: 2001-04-17, release date: 2001-04-25, Last modification date: 2024-02-07)

Primary citation

Andersson, M.,Malmendal, A.,Linse, S.,Ivarsson, I.,Forsen, S.,Svensson, L.A.
Structural basis for the negative allostery between Ca(2+)- and Mg(2+)-binding in the intracellular Ca(2+)-receptor calbindin D9k.
Protein Sci., 6:1139-1147, 1997

PubMed Abstract: 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.

PubMed: 9194174

Experimental method

X-RAY DIFFRACTION (1.5 Å)