1snl
From Proteopedia
NMR Solution Structure of the Calcium-binding Domain of Nucleobindin (CALNUC)
Structural highlights
Function[NUCB1_HUMAN] Major calcium-binding protein of the Golgi. May have a role in calcium homeostasis (By similarity). Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedNucleobindin, also known as calnuc, participates in Ca2+ storage in the Golgi, as well as in other biological processes that involve DNA-binding and protein-protein interactions. We have determined the three-dimensional solution structure of the Ca(2+)-binding domain of nucleobindin by NMR showing that it consists of two EF-hand motifs. The NMR structure indicates that the phi and psi angles of residues in both motifs are very similar, despite the noncanonical sequence of the C-terminal EF-hand, which contains an arginine residue instead of the typical glycine at the sixth position of the 12-residue loop. The relative orientation of the alpha-helices in the N-terminal EF-hand falls within the common arrangement found in most EF-hand structures. In contrast, the noncanonical EF-hand deviates from the average orientation. The two helix-loop-helix moieties are in the open conformation characteristic of the Ca(2+)-bound state. We find that both motifs bind Ca2+ with apparent dissociation constants of 47 and 40 microM for the noncanonical and the canonical EF-hand, respectively. The Ca(2+)-binding domain of nucleobindin is unstructured in the absence of Ca2+ and folds upon Ca2+ addition. NMR relaxation data and structural studies of the folded domain indicate that it undergoes slow dynamics, suggesting that it is floppier and less compact than a globular domain. Structural studies on the Ca2+-binding domain of human nucleobindin (calnuc).,de Alba E, Tjandra N Biochemistry. 2004 Aug 10;43(31):10039-49. PMID:15287731[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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