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From Proteopedia
NMR Structure of Human apoS100B at 10C
Structural highlights
FunctionS100B_HUMAN Weakly binds calcium but binds zinc very tightly-distinct binding sites with different affinities exist for both ions on each monomer. Physiological concentrations of potassium ion antagonize the binding of both divalent cations, especially affecting high-affinity calcium-binding sites. Binds to and initiates the activation of STK38 by releasing autoinhibitory intramolecular interactions within the kinase. Interaction with AGER after myocardial infarction may play a role in myocyte apoptosis by activating ERK1/2 and p53/TP53 signaling (By similarity). Could assist ATAD3A cytoplasmic processing, preventing aggregation and favoring mitochondrial localization.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedS100B is one of the best-characterized members of the calcium-signaling S100 protein family. Most S100 proteins are dimeric, with each monomer containing two EF-hand calcium-binding sites (EF1, EF2). S100B and other S100 proteins respond to calcium increases in the cell by coordinating calcium and undergoing a conformational change that allows them to interact with a variety of cellular targets. Although several three dimensional structures of S100 proteins are available in the calcium-free (apo-) state it has been observed that these structures appear to adopt a wide range of conformations in the EF2 site with respect to the positioning of helix III, the helix that undergoes the most dramatic calcium-induced conformational change. In this work, we have determined the structure of human apo-S100B at 10 degrees C to examine whether temperature might be responsible for these structural differences. Further, we have used this data, and other available apo-S100 structures, to show that despite the range of interhelical angles adopted in the apo-S100 structures, normal Gaussian distributions about the mean angles found in the structure of human apo-S100B are observed. This finding, only obvious from the analysis of all available apo-S100 proteins, provides direct structural evidence that helix III is a loosely packed helix. This is likely a necessary functional property of the S100 proteins that facilitates the calcium-induced conformational change of helix III. In contrast, the calcium-bound structures of the S100 proteins show significantly smaller variability in the interhelical angles. This shows that calcium binding to the S100 proteins causes not only a conformational change but results in a tighter distribution of helices within the EF2 calcium binding site required for target protein interactions. Proteins 2008. (c) 2008 Wiley-Liss, Inc. Analysis of the structure of human apo-S100B at low temperature indicates a unimodal conformational distribution is adopted by calcium-free S100 proteins.,Malik S, Revington M, Smith SP, Shaw GS Proteins. 2008 Apr 2;. PMID:18384084[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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