1cb1
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THREE-DIMENSIONAL SOLUTION STRUCTURE OF CA2+-LOADED PORCINE CALBINDIN D9K DETERMINED BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY
OverviewOverview
The three-dimensional solution structure of native, intact porcine, calbindin D9k has been determined by distance geometry and restrained, molecular dynamics calculations using distance and dihedral angle, constraints obtained from 1H NMR spectroscopy. The protein has a, well-defined global fold consisting of four helices oriented in a pairwise, antiparallel manner such that two pairs of helix-loop-helix motifs, (EF-hands) are joined by a linker segment. The two EF-hands are further, coupled through a short beta-type interaction between the two, Ca(2+)-binding loops. Overall, the structure is very similar to that of, the highly homologous native, minor A form of bovine calbindin D9k, determined by X-ray crystallography [Szebenyi, D. M. E., & Moffat, K., (1986) J. Biol. Chem. 261, 8761-8776]. A model structure built from the, bovine calbindin D9k crystal structure shows several deviations larger, than 2 A from the experimental distance constraints for the porcine, protein. These structural differences are efficiently removed by, subjecting the model structure to the experimental distance and dihedral, angle constraints in a restrained molecular dynamics protocol, thereby, generating a model that is very similar to the refined distance geometry, derived structures. The N-terminal residues of the intact protein that are, absent in the minor A form appear to be highly flexible and do not, influence the structure of other regions of the protein. This result is, important because it validates the conclusions drawn from the wide range, of studies that have been carried out on minor A forms rather than the, intact calbindin D9k.
About this StructureAbout this Structure
1CB1 is a Single protein structure of sequence from Sus scrofa. Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional solution structure of Ca(2+)-loaded porcine calbindin D9k determined by nuclear magnetic resonance spectroscopy., Akke M, Drakenberg T, Chazin WJ, Biochemistry. 1992 Feb 4;31(4):1011-20. PMID:1734952
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