1snl
From Proteopedia
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NMR Solution Structure of the Calcium-binding Domain of Nucleobindin (CALNUC)
Overview
Nucleobindin, 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.
About this Structure
1SNL is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
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
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