1ig5: Difference between revisions

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.

1IG5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with MG as [http://en.wikipedia.org/wiki/ligand ligand]. This structure superseeds the now removed PDB entry 5ICB. Structure known Active Site: MUM. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1IG5 OCA].  

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